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U. S. DEPARTMENT OF LABOR
JA M E S J. D A V IS , Secretary

CHILDREN’S BUREAU
G R A C E A B B O T T . Chief

CAUSAL FACTORS IN INFANT
MORTALITY
A STATISTICAL STUDY BASED ON
INVESTIGATIONS IN EIGHT CITIES

ROBERT MORSE WOODBURY. Ph. D.

Bureau Publication No. 142

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SINGLE COPIES OF THIS PUBLICATION M AT BE
OBTAINED FBEE UPON APPLICATION TO THE
CHILDBEN’ S BUREAU.

ADDITIONAL COPIES MAT

BE PROCURED FROM THE SUPERINTENDENT OF
DOCUMENTS, GOVERNMENT PRINTING OFFICE,
WASHINGTON, D . C.
AT

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C O N TEN TS

Letter of transmittal__________________________________________
Introductory summary________________ .___________________________________ ;___
Basic material and methods of analysis_____________ ________________________ *
Basis of study____________________________________ _____ ___________________
Limitations of material__________________________________
Methods of field studies_________ ^____________________ * ______ ___________
Methods of analysis_____________ _ ___________________ ___________________
Pathological causes of death___________________________ ________ _______ _ _.___
Causes peculiar to early infancy. _ _____________________ ____________ ____
Gastric and intestinal d i s e a s e s _____________________________________
Respiratory diseases___________________________________________
Epidemic and other communicable diseases________________________
Malformations___________________________________________________ •_______
Other causes_______________________________________________________________
Significance of comparisons with rates in birth-registration cities and
in New Zealand_____________________________________________ ___ _______
Age of infant__________________________ ____________
Seasonal conditions______________________________________________________
M onth of birth______________
Sex of infant_________________________ _________________________________________
Physical condition ’of m other_______________________________ _________________
Death of mother___________________________________ ______________________
Causes of death of infant___________ __________ _____________________
Prematurity______________________________________________
Type of feeding______________________________
Tuberculosis of m o th e r -_________________________ ________;___________ ___
Complications of pregnancy and c o n f i n e m e n t - ___________________
Medical care during pregnancy_______________
Summary________________________________________________ . _ _ _ ______ ______
Frequency of births___________________________
Age of mother_________ __________________ t?___ i—______ ________________ _
Causes of death of in fa n t..:________________________ ___ _________;
Neonatal mortality____________________ _______________:_____ _
Order of birth________________________ :_________________ ____ ___ji.>__
Interval since preceding birth_____________
Prematurity____________ __ Li______________________ ____________ ____
Plural births_________________________________________ ___________ ____
Type of feeding__________________ ____ _____ t____ ________ ________ _
Color and nationality o f mother___ ___________ ___________________
Earnings of father_______________________________________ ___________
Summary_____________________________________________________________
Order of birth________________ ____________________ ______________ jg£_______
Causes of death_________________________________________ _____ _______
Neonatal mortality__________________________________
Age of m other__________ _______________________ ______ _ &-------------- Interval since preceding b ir th .;______________ _______ _____________
Age of mother and interval since preceding b irth .________________
Prematurity______________________________
Plural births__________________
Type of feeding_____________ ____________ ____________________ _______
Color and nationality of mother___ ____________ ________________ _
Earnings of father_______________
Per capita earnings________
Summary_______________
Interval since preceding birth____ ___________________ * ___________ >_______
Causes of death_________________
Neonatal mortality__________________________________
Age of mother and order of birth___________________________________

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CONTENTS

Frequency of births— Continued.
Interval since preceding birth— Continued.
Prematurity__________________________________________________________
Plural births__________________________________________
Type of feeding.- ---------------- . . . . ----------. -----------------------------------------Color and nationality of mother______ _________________ ___________
Earnings of father____________________________ :---------------------------------Summary_______________________________ p i ---------------------------------------Interval before succeeding pregnancy___________________________________
Type of feeding_______________________________ ___________ %---------------*
Color and nationality of m other.
Earnings of father-----------------------------------------------_ _ . ------------------------Summary___________________ _________ _______ _ i _ . ___________________
General sum m ary______________ _______ --------------------- ------------------- - ------Type of birth_________________________________________________________
Prematurity______________ ___ Ju-----------------------. . . --------------------- - — - - Causes of death________ ___ _ . _ . _____ ■—
-------------------------------Neonatal mortality______________ ------------------------------------------ ;.. . —
Plural births_________________ ^ -------------- -— --------- ».-*------- ------------Sex_______________________________----------------- -------------------------------------Death, of mother___________________ _ Jj—
---------------------------------- —
Type of feeding----------------------------------. ---------------------------------------------Other factors---------. ----------------- ---------------------------------------------------------Causes of prematurity-------------------------------- -- _ ---------------------------------Summary____________________ ---------------------------\---------------------------------Plural births___________________________ ----------------- -------- -----------------------■. _
Causes of death________________ .,____________:------------------- . - _ . . —
Neonatal mortality----------------- _ . . . --------------------------------------------------Prematurity---------- ------------------- --------- mM , -------------- - - - — ------------Causes of death and prematurity___________________________________
Type of feeding______________________ _ — -------------------- ------------------Prematurity and type of feeding-----------------------------------------------------Other factors_____________ ____________ _— ----------------------------------M ortality among pairs of twins________-----------------------------------------Causes o f plural births___ . - .. . ■ - . . ---------------------------------------------------Sum m ary--------- ----------------------------------- ------------- . ------------------------------T ype of delivery____________________________ 1 . -----------------------------------------Type of feeding______________________________. . . . ______ J|---------------------------- •Prevalence of breast and artificial feeding--------------------------------------------M onthly death rates, by type of feeding-------------------------- --------------------Influence of changes in feeding
-------— . ----------- ------------ . - . . . ----------Cumulative influence of early artificial feeding.----------------- ---------------Causes of death----------------------------------------- ----------------------------------------------Plural births, prematurity, and death of mother---------------------- Color and nationality of mother___________________ — --------- ----------------Employm ent of mother during first year of infant’s life----------------------Earnings of father______________ ________________________ ______*------------ Varying prevalence of early artificial feeding-------------------------- . . . . . —
Summary___ . . . --------------- ---------------------------------------------- 1 -----------------------Color and nationality of mother------------------------------- ---------------------- -------- . . . .
Causes of death of infant---- . . . -------------- ...---------------- --------- ------------------Neonatal mortality------------ . --------------- ----------- -*-<-------— ■- - - -----------------Plural births and prematurity-------------------------------------------- --------------------Death of mother--------------------------------*. — ---------------------------------- 107
Plural births, prematurity, and death of m o t h e r — -----------------Instrumental delivery---------------. . . ----------------- . . . ------------- ---------------------Frequency of births----- ------- ---------------- . . . ----------- r — ------------------- _ _ _ .
Age of mother______________ — --------- :-------------------. . . . . . . --------- . . .
Order of birth________________ _______ **-------------<-------------------------------Interval since preceding birth______________________________________
Interval before succeeding pregnancy---------------------------- ------- . ------T ype of feeding__________________________________________________________ Housing congestion..,_______________________ . . . . . . ------- - — -----------------Employment of mother during pregnancy---------- ,-------. . . . ---------- ---------Employment of mother during first year of infant’s l i f e .------------ — .
Earnings of father__________________________________ , — ---------- ----------------Earnings of father and type of feeding--------------------------------------------------Summary-------------------------- -------------------- ------------------------------------------------ .—

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CONTENTS

-y

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Housing congestion__________________________
Causes of death__________________ ________________ .__________________ I I ” I
Type of feeding------------------------------------------------------------------- I I I I I I I I I I I .
Color and nationality of mother_______________________ ________________
Earnings of father__________________ _ _____________________________________
Earnings of father and nationality of mother___________ _______________
Summary____________________________________________ _ _______________ I ___ _
Economic factors______________ ____________________ ____________________________
Employment of mother during pregnancy______________________________
Causes of death of infant______________ i ____________ _______________
Neonatal mortality______________ ____________ _ _ ___________________
Interval between cessation of work and confinement_____ _______
Prem aturity.__________________________ _____________________ _______ ; _
Type of feeding________ _ _ __________ _____________ __________________
Color and nationality of mother_________ ___________________________
Earnings of father_________ _________________________ ________________
Em ploym ent of mother during infant’s life________ _______________
Causes of employment of mother during pregnancy______________
S u m m ary .________ „ ___________________________________ ______________
Employment of mother during first year of infant’s life_____________ _
Causes of death_________ ________ _______________________ ,________ _
Interval between confinement and resumption o f work__________
Type of feeding___________________________________
Color and nationality of mother___________________ ________________
Earnings of father__________ _ _ ________________ ____________________ I
Causes of mother’s employment during infant’s life ._____________
Summary____________ _______________________________ _______________^
Earnings of fath er._____________________________________ _________________
Additional income______________________________________________ \____
Earnings per capita of fam ily_________________ ._ ____________ _______
Causes of death of infant___________ __________________ _._________ _
Neonatal mortality________________ ' _ _________ ___________________ ___
Plural births, prematurity, and death of m o t h e r ...______________
Age of mother, order of birth, interval since preceding birth, and
interval before succeeding pregnancy. _*_________________________
Type of feeding_________ ________ . . . ______________________________ 155
Color and nationality of m oth er.________________________ __________
Housing congestion_____ _________ __________________ ._il_________ _ _
Employment of mother during pregnancy_____ ___________________
Employment of mother during first year of infant’s life________ _
Chain of causation linking earnings of father and infant mortality _ _
Causes of low father’s earnings and of low per capita income___
S u m m ary .__________________________
Appendix A .— Stillbirths_____________ ________ _________ _____ /_._____________
Appendix B.— Method of study_______ ______. . . ___ _________________ I _____I
Appendix C.— Method of analysis___________ ______________ __________________
Appendix D .— General tables____ •__________ ______ _________________________
Appendix E .— Charts______________

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G E N E R A L TAB LE S
Table -1.— Cause of death, by month of life in which death occurred;
infant deaths in eight cities___________________________________
Table 2 .— Cause of death, by calendar month of birth; infant deaths in
eight c i t i e s ..._________ ____ ____ _______ _______________________
Table 3.— M onth of life in which death occurred, by calendar month of
birth; infant deaths in eight cities___________________________
Table 4.— Infant mortality rates, by sex and term ; live births in eight
y
cities____________ ________________________________________________
Table 5.— Prevalence of artificial feeding, by sex and month o f life;
infants in eight cities_______ ____________ ______________________
Table 6 .— Proportion of births to mothers of nationalities with high in
fant mortality rates, by sex; live births in eight cities______
Table 7.— Infant mortality, by cause of death, term, and interval be
tween confinement and death of mother; births in eight
cities to mothers who died a t or within one year after con
finement____ ______________________ ________________________________

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8.— •Type of feeding, by month of life; infants in eight cities
whose mothers died a t or within one year after confinement- _
Table 9 — -Prevalence of breast and artificial feeding, by death or survival
of mother during year after confinement; infants in eight
cities_______________________________________ |------ -------- T: - l --------Table 1 0 - -Mortality among infants whose mothers died a t or within one
year after confinement as compared with all other infants,
when influence of differences in type of feeding is eliminated;
infants in eight cities________________________________ . _________
Table 1 1 - -Causes of death of infants in Baltimore, according to whether
mother had had tuberculosis--------------------------------------------------Table 1 2 .- -Proportion of births to mothers in Baltimore who had con
vulsions as a complication of confinement, by term and cause
of infant’s death------------------------------------------------------------- — r - Table 13.- -Infant mortality rates, by cause of infant’s death and medical
prenatal care of mother; live births in Baltimore--------------- -Table 14.- -M onthly death rates, by age of mother and month of life;
infants in eight cities-------------------- ------------------------------------ -j-----Table 15 .- -Age of mother, b y order of birth; live births in eight cities. _
Table 1 6 - -Relative mortality, by age of mother, when influence of order
of birth, interval since preceding birth, and both factors
together, is eliminated; live births in eight cities and live
births in Baltimore__________________; - - -------------------- --------------Table 1 7 - -Order of birth, by interval since preceding birth and age of
mother; single live births in Baltimore second and later in
order.
______________ ____________ ______________________ — Table 1 8 - -Proportion of births following preceding birth a t short inter
vals, by order of birth and age of mother; single live births
in Baltimore____________________________________________ - - _____
Table 19.- -Proportion of premature births, by age of mother, when influ
ence of order of birth is eliminated; live births in eight cities.
Table 20.- -R elative mortality, by age of mother, when influence of pre
maturity is eliminated; live births in eight cities-------- -— ^
Table 2 1 - -Proportion of confinements with instrumental delivery, by age
of mother; confinements in Baltimore------------ ----------- ----------Table 2 2 - -Prevalence of artificial feeding, by age of mother and month
of infant’s life; infants in eight cities-------------------------------- . . .
Table 23.- -A ge of mother, by color and nationality of mother; live
births in eight cities----------------------------------------------------------- - —
Table 24.- -A g e of mother, by earnings of father and whether first or later
births; live births in seven cities— ---------------------- ---------- ------Table 2 5 - -A ge of mother, by per capita income from father’s earnings;
live births in seven cities----- ------------------------------- --------------- 7- Table 26.- -M on th ly death rates, by order of birth and month of life;
infants in eight cities---------------------------------------------------------------Table 27.- -Relative mortality, by order of birth, when influence of pre
maturity and plurality of birth is eliminated; live births
in eight cities--------- ------------------------------------------ --------- ------------- Table 28.- -R elative mortality, by order of birth, when influence of
interval since preceding birth, and when influence of both
interval since preceding birth and age of mother is elimi
nated; single live births in Baltimore second and later in
order_________________________5-----------------------------------------------------Table 29.- -Proportion of confinements with instrumental delivery, by
order of birth; confinements in Baltimore------------ -------------Table 30.- -Prevalence of artificial feeding, b y order of birth and month
of life; infants in eight cities---------------------------------- ---------------Table 31.- -O rder of birth, by color and nationality of mother; live births
in eight cities______________________________________ — - -----------Table 32.- -O rder of birth, b y earnings of father; live births in seven cities.
Table 33.- -O rder of birth, by per capita income from father ’s earnings; live
births in seven cities------------------------------ ---------- --------------------- Table 34.- -M o n th ly death rates, by interval since preceding birth and
month of life; infants in Baltimore----------------------- ^— ------- —
Table 35.- -P e r cent of premature births, by order of birth and interval
since preceding birth; live births in Baltimore............. ..............

Table

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Page

Table 36.— Prevalence of artificial feeding, b y interval since preceding
birth and month of life; infants in Baltimore________________
Table‘ 37.— Interval since preceding birth, by color and nationality of
mother; live births in Baltimore____ _______ ;_________________ _
Table 38.— Interval since preceding birth, by earnings of father; live
births in Baltimore second and later in order________________,
Table 39.— Interval since preceding birth, by pier capita income from
father’s earnings; live births in Baltimore____________________
Table 40.— Prevalence of breast and artificial feeding when mother be
came pregnant; infants in Baltimore whose mothers became
pregnant during first year of infant’s l i f e ________ ___________
Table 41.— Cause of death, by month of life in which death occurred;
deaths among infants in eight cities whose mothers became
pregnant in some preceding m onth_______ ________ ____________
Table 42.— T ype of feeding during months lived to end of ninth and after
commencement of m other’s subsequent pregnancy; infants
in eight cities whose mothers became pregnant during in
fant’s first year_____ __________________________________ i _______
Table 43.— Type of feeding after beginning of m other’s subsequent
pregnancy, by month of life; infants in Baltimore whose
mothers became pregnant during first year of infant’s life. _
Table 44.— Cause of death, by term ; infant deaths in eight cities___ _
Table 45.— Monthly death rates, b y month of life and term ; infants in
eight cities________ _______________ ___________ ___________* _ J___
Table 46.— Infant mortality and stillbirth rates, by period of gestation
and single and plural births; births in eight cities____________
Table 47.— Proportion of births to mothers who died a t or within one
year after confinement, by term ; live births in eight cities-Table 48.— Type of feeding, by month of life and period of gestation;
infants in eight cities_______•_■_________________________ _________
Table 49.— Prevalence of breast and artificial feeding during first nine
months, by term and single and plural births; months lived
by infants in eight c itie s --____________ ____________ _____ .____
Table 50.— Proportion of births fifth and later in order, b y term ; live
births in eight cities_____________ _____i__________ _________206
Table 51.— Proportion of births to mothers under 2 0 and to those 35
years of age and over, by term ; live births in eight cities____
Table 52.— Proportion of births following preceding births after short
intervals, by term ; live births in Baltimore________U_______
Table 53.— Proportion of births to mothers of nationalities with high
infant mortality rates, b y term ; live births in eight cities__
Table 54.— Proportion of births in families in which fathers earned less
than $650, by term ; live births in seven cities___ ___________
Table 55.— Proportion of births to mothers employed away from home
during pregnancy, b y term ; live births in eight cities_______
Table 56.— Death in infancy and survival o f twins in pairs, b y character
of birth and period of gestation; twins in eight cities_______
Table 57.— M onthly death rates, by month of life and single and plural
births; infants in eight cities_____ ____________ _______ ___ *.___
Table 58.— Type of feeding, by month of life and single and plural births;
infants in eight cities_____ _____________ ______ ;_____ _________ _
Table 59.— Weaning of twins in pairs, by age when first twin was weaned;
twins in six cities
_ _____ 2 ___________ _ ________________ _______
Table 60.— Proportion o f births to mothers under 20 and to those 35 and
over, by single and plural births; live births in eight cities. _
Table 61.— Proportion of births fifth and later in order, by single and
plural births; live births in eight cities______________ .________
Table 62.— Relative mortality among plural and single births, when
influence of age of mother, order of birth, and both factors
is eliminated; live births in eight cities____ ;_______ _______ _
Table 63.— Proportion of births to mothers of nationalities with high
infant mortality rates, by single and plural births; live
births in eight c itie s.-___ ________________ ____________ _________
Table 64.— Proportion of births in families in which fathers earned less
than $650, by single and plural births; live births in eight
cities-______________________ _______________________ ___ __________

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CONTENTS

Page
Table 65.— Prevalence of plural births among births preceded by plural
births; all pregnancies reported by mothers of infants in
eight cities---- _ ----------- ,--------------------------------_ —
___________ * 211
Table 66 .— Proportion of confinements in families in which father earned
less than $650, by type o f delivery; confinements in Balti
more_______________________________ _______ ...-------------- -------------211
Table 67.— M onthly death rates, by cause of death, type of feeding, and
month of life; infants in eight cities____ :_____________________
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Table 68 .— M onthly death rates of infants artificially fed, by month of
life in which artificial feeding began; infants artificially fed
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in eight cities------- ------------- _ . ------- -------------------------------------------Table 69.— M onthly mortality o f infants artificially fed, by month of life
in which artificial feeding began; single, full-term live
births in eight cities to mothers who survived first year of
infant’s life___ ____________*___n______ __________________ ______ _ _
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Table 70.— M onthly death rates, by month of life and color and nation
ality of mother; infants in eight cities_____ _ ______ ------------- *
215
Table 71.— Type of feeding, b y color and nationality of mother; months
lived from birth to end of ninth by infants in eight cities- _
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Table 72.— Prevalence of breast and artificial feeding, by month of infant’s
life and color and nationality of mother; infants in eight
cities____________________________ ______ ____________________ _____
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Table 73.— M onthly death rates, b y color and nationality of mother and
by month of life and type of feeding; infants in eight cities__
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Table 74.— Relative mortality, by nationality of mother, for infants; not
fed and for infants receiving each type of feeding; eight
cities, A ___________________________ _________________ ___________
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Table 75.— Color and nationality of mother, by average number of per
sons per room ; infants in seven cities who survived two
weeks_________________________ _ . _________3______________________
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Table 76.— Earnings of father, b y color and nationality o f m other; live
births in seven cities. ---------------- -----------------------------------------------221
Table 77.— Average per capita income from father’s earnings, b y color
and nationality o f m other; live births in seven cities_______
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Table 78.— M onthly death rates, by month of life and average number
of persons per room ; infants in seven cities who survived
tw o weeks____ _________________ _______ _______________________
223
Table 79.— Prevalence of artificial feeding in selected months, by average
number of persons per room ; infants in seven cities who
survived two weeks______- —
___________________________
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Table 80.— Earnings of father, by average number o f persons per room ;
infants in seven cities who survived two weeks___ __________
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Table 81.-— Average number of persons per room, by per capita income
from father’s earnings; infants in seven cities who survived
two weeks____________________ a____ ________________ _ __________
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Table 82.— M onthly death rates, by month of infant’s life and employ
ment of mother during pregnancy; infants in eight cities—
225
Table 83.— Proportion of plural births, by employment o f mother during
, pregnancy; live births in eight cities________________ .________
225
Table 84.— Prevalence o f artificial feeding, by month of life and employ
ment of mother during pregnancy; infants in eight cities. _
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Table 85.— Em ploym ent of mother away from hom e, by interval between
cessation o f work and confinement, and earnings of father;
live births in seven cities. _ _ _ _ . : ----------------—
---------------226
Table 86 .— Em ploym ent of mother during pregnancy, by her employ
ment during first year of infant’s life; Infants in eight cities.
226
Table 87.— T ype of feeding in month in which mother went to work, by
place of her employm ent; infants in eight cities surviving
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when mothers went to work____________________________ ______
Table 88 .— T ype of feeding, by month of infant’s life and place of mother’s
employm ent; infants in eight eities whose mothers were
employed during some preceding m onth of infant’s life___
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Table 89.— T ype of feeding during first nine months of life, by employ
ment of m other; infants in eight cities_____ ________________
228
Table 90.— Earnings of mother, by earnings of father; infants in seven
cities whose mothers were employed during first year of
infant’s life____________________________________________________
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Co n t e n t s

Table

91.— Earnings of children in family, by earnings of father; live
births in seven cities in families in which one or more
children worked during year following the births__________
229
Table 92. Infant mortality rates, by total annual income of family and
earnings of father; live births in seven cities_______________
230
Table 93.— Earnings of father, by average per capita income from father’s
earnings; live births in seven cities. _ ________________________
230
Table 94. Infant mortality rates, by cause of death and economic need;
live births in seven cities______________________________
231
Table 95.— M onthly death rates, by m onth of infant’s life and"earnings
of father; infants in seven cities____________ ________________
231
Table 96.— Proportion of plural births, by earnings of father; live births
in seven cities______________________________________________
232
Table 97.— Proportion of births to mothers who died at or within "one
year after confinement, by earnings of father; live births
in seven cities_____________________________________________________ 232
Table 98.— Relative infant mortality, by earnings of father, when influ
ence of age of mother and order of birth, and of interval
since preceding birth is eliminated; single live births in
232
seven cities and live births in Baltimore____________________
Table 99.— Prevalence of breast and artificial feeding, by month of infant’s life and earnings of father; infants in eight cities___
233
Table 100.— Type of feeding during first nine months of life, by earnings
of father; infants in seven cities_________________ ___________
234
Table 101.— M onthly death rates, by type of feeding, earnings of father,
and month of life; infants in seven cities___________________
235
Table 102.— Infant mortality rates, by earnings of father and color and
nativity of mother; live births in seven cities______________
236
Table 103.-*—Proportion of confinements with instrumental delivery, by
earnings of father; confinements in Baltimore_____________
236

CHARTS
Qhart

Deaths from respiratory and from gastric and intestinal
diseases, by month of death__ _____________________________
II.— M onthly death rates, by month of life_______________________
H I-— Infant mortality rates, by age of mother_____________________
I V .— Infant mortality rates, by order of birth____________ ___[____
V .— Infant mortality rates, by interval since preceding birth__
V I.— Infant mortality rates for single and plural, premature and
full-time births_______________________________________________
V II .— Relative mortality, by type of feeding_______________________
V II I.— Infant mortality rates, by color and nationality of m other. _
IX .
Infant mortality rates, by color and nativity of mother and
earnings of fath er_________________________________

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LE TTE R O F T R A N SM IT TA L

U. S. D epartment

op L abor ,
Children ’ s B ureau ,

’Washington, February 25, 1925.
There is transmitted herewith a report on Causal Factors in
Infant Mortality, by Dr. Robert Morse Woodbury, director of
statistical research in the Children’s Bureau. This report is a sum
mary of the detailed studies of infant mortality made by the bureau
in eight cities.
The much larger number of infants for which material is available
in this consolidated report permits an extended analysis of some of
the more important factors m infant mortality and affords the basis
for conclusions as to causes not considered in the reports on individual
cities because of the relatively smaller numbers. In the analysis
Dr. Woodbury has used the method of expected deaths developed
by Prof. Harald Westergaard, of the University of Copenhagen, in
order to isolate the influence of each cause under consideration.
Respectfully submitted.
Grace A bbott, Chief.
Hon. James J. D avis ,
Secretary o f Labor.
Si r :

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CAUSAL FACTORS IN INFANT MORTALITY
IN TR O D U C TO R Y SU M M A R Y

A thorough knowledge of the causes of infant mortality is the
first step toward their complete control. In the light of such knowl
edge preventive measures may be intelligently planned to produce
a maximum of result. These measures may be aimed to prevent
the spread of specific infectious diseases—for example, vaccination
for smallpox, the Schick test and toxin-antitoxin immunization
against diphtheria, disinfection of the eyes to prevent ophthalmia
neonatorum, or the practice of surgical cleanliness to prevent tetanus
and other infections immediately following birth. They may be
directed toward the control of gastric and intestinal diseases, to
effect which involves not simply the prevention of infection but the
inculcation of right principles of infant feeding. Again, they may
be directed toward the control of the mortality of early infancy,
the main causes of which lie in the care and condition of the mother
during pregnancy and childbirth.
The pathological causes of infant deaths must be reported on
death certificates by the physicians in attendance. These certificates
therefore, state the specific condition or disease that resulted in
death, whether malformation, congenital debility, enteritis, measles,
or some other cause. They furnish the basis for the preliminary
study of causes of death and also for an index of the maximum limit
of efficacy of measures of prevention, so far as those measures are
directed toward the control of particular causes of death.
But the analysis, if it is to be thorough, must be carried beyond
the pathological cause to antecedent and predisposing causes and
causal factors. Differences in inborn vigor or vitality may account
in part for differences in the rates for the different races, even as
they may account for differences in the rates for male and female
infants or for twins and triplets and single-born infants. The
prejudices and traditions of certain race groups have their influence
upon the infant mortality rates for these races, as, for example, the
custom of mothers of Portuguese extraction of giving “ sopa,” a
dish prepared from softened crackers, to babies a few hours old, or
the preference of Italian women to be attended at confinement by
midwives and their custom of wrapping their “ bambinos” in swad
dling clothes. The influence of type of feeding and other elements
of infant care demands careful consideration in the study of causes
of infant mortality.
The program recommended for pregnant women by medical
authorities includes supervision by a physician, nourishing food,
rest, and. freedom from worry and overwork. These excellent
prescriptions cost money; and the mother who is struggling to make
ends meet upon a meager income may be unable to follow such
1

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CAUSAL FACTORS IN IN F A N T MORTALITY

recommendations. The analysis, therefore, must also attempt to
assess the importance of insufficiency of income as an underlying
cause. The comparison of mortality rates in the different income
groups should indicate to what extent infant mortality might be
prevented if the most favorable conditions prevailed among all
groups. Another important element in the condition of the mother
which may affect her baby’s chances of life is whether or not she is
employed; it is important, therefore, to ascertain the nature and
extent of the influence of the mother’s employment upon infant
mortality. In the present study an attempt is made to evaluate
these underlying, as well as the pathological, causes of infant
mortality.
The data available for analysis consisted of nearly 23,000 records
of infants born in eight cities and the deaths under 1 year of age
among them. The infant mortality rate from all causes in the group
studied was 111.2 per 1,000 live births'.
Pathological causes o f death.

The group of causes peculiar to early infancy was first in impor
tance and was responsible for nearly one-third of the deaths under
1 year; the rate of mortality from these causes was 36.1. Gastric
and intestinal diseases were not far behind with a rate of 32.4. Re
spiratory diseases ranked third with a mortality of 19.6; and the
rate from epidemic and other communicable diseases was 7.1.
Age o f infant.

The mortality rate decreased month by month during thé first
year of life, dropping from 44.8 in the first to 9.3 in the second
month and falling more slowly in the following months to 4.5 in the
twelfth. The trend of the mortality rates from the several causes
varied markedly with increasing age: From causes peculiar to early
infancy the mortality dropped from 30.3 in the first to practically
negligible figures in later months. From respiratory diseases it de
creased gradually from 2.9 in the first to 1.2 in the twelfth month.
From epidemic and other communicable diseases the rates varied in
trend according to the specific cause. From gastric and intestinal
diseases the rate increased from 3 in the first to a maximum of 3.8
in the sixth month, after which time it decreased to 1.8 in the twelfth
inonth. Upon analysis this change in incidence was found to be in
fluenced by type of feeding; among the exclusively breast fed the
mortality from these diseases showed a continuous decrease from
the first month, whereas among the exclusively artificially fed the
rate, which was relatively very much higher, increased from 8.3 in
the first to a maximum of 11.1 in the third month. The trend of the
average rates of mortality from these diseases was influenced largely
by transfers from breast to artificial feeding during the early months
of life.
Seasonal conditions.

Marked differences in mortality in different seasons were found,
which varied according to the cause of death. From gastric and
intestinal diseases the maximum mortality occurred in August and
was 13 times the minimum, which occurred in January. From
respiratory diseases the maximum mortality, in February, was seven
times the minimum, in August. Epidemic and other communicable

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diseases appeared to have been slightly more prevalent in the late
winter and early spring than in the other months.
M onth o f birth.

The mortality was lowest for infants born in August and highest
for those born in June. Since the variation in the seasonal incidence
of gastric and intestinal diseases was greatest, the differences in
mortality rates for infants born in different months were determined
largely by the relation which the month of birth bore to the infants’
ages when they were exposed, during the summer, to the heaviest
incidence of these diseases.
Sex.

The mortality rate for male was about one-fourth higher than that
for female infants. This excess mortality among males was found for
ractically every cause of death and among both the prematurely
orn and those born at term. Though greater difficulty of labor in
case of male births might.explain the excess mortality from causes
peculiar to early infancy, the greater mortality from other causes
appears to be explainable only b y differences in vitality to the dis
advantage of the male sex.

Physical condition o f mother.

Though the information obtained relating to the physical condi
tion of the mother was limited to a comparatively few points, each of
these points appeared to exert a great influence over infant mortality.
Infants of mothers who died within one year after confinement had
a mortality from all causes which was over four times and a mortality
from causes peculiar to early infancy which was seven times the
corresponding rates for those whose mothers lived for a year or more
after confinement. Among infants whose mothers died within one
month the excess mortality was especially great. A disproportionate
number of infants whose mothers died within one year were prema
turely born, and a disproportionate number were artificially fed ; but
neither the greater prevalence of prematurity nor the greater amount
of artificial feeding was sufficient to account for their much heavier
mortality.
A small group of infants whose mothers were known to have had
tuberculosis had a mortality from all causes, and especially from
tuberculosis, which Was greatly in excess of that among other infants.
The mortality among infants whose mothers were reported to have
had convulsions as a cdmplication of pregnancy or confinement was
three and one-half times the average, the excess mortality being
due largely to causes peculiar to early infancy.
Other points which are associated closely with the mother’s health
or physical condition during pregnancy and at confinement are dis
cussed under the following topics: Age of mother, order of birth,
employment of mother during pregnancy, and earnings of father.
Frequency o f birth.

The factors which together produce the influences upon infant
mortality frequently associated with the birth rate are order of
birth, age of mother, interval since preceding birth, and interval
before succeeding pregnancy.
Order o f birth.— The mortality rate for first-born was slightly
higher than that for second-born infants. On analysis this excess

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mortality among first-born infants was found to be due largely to
a higher death rate from causes peculiar to early infancy and to a
greater proportion of premature births. From gastric and intestinal
and from respiratory diseases, on the other hand, the mortality
among first-born was less than that among later-born infants.
When the first born were left out of account the mortality rate
tended to increase with order of birth. The analysis indicated that
this tendency was associated primarily with increasing economic
pressure as the number of children in the family increased, for when
allowance was made for this factor, so far as the material permitted,
the higher mortality found among the later orders largely disap
peared.
Age o f mother.—Among the first born the infants of mothers under
20 and of those 40 years of age and over had the highest mortality
rates. These variations were probably associated with physical
immaturity or with changes in the physical condition of the mother.
Among the second and later born the age of the mother appeared
not to exert any marked influence as distinguished from other factors
with which it was associated. The high rate found for infants of
the youngest mothers was explainable in part by short-interval
births and in part by relatively low economic status; that for infants
of the oldest mothers was largely a reflection of high rates associated
with later orders of birth and with relatively great economic pressure.
Interval since 'preceding birth.— The mortality rate was highest for
infants born at short intervals after preceding births—the short
interval representing a difference of-only one year in their mo thers’
ages, measured in even years, at the successive births— and lowest
for infants who followed preceding births at intervals of four years
or more, as thus measured. This difference could not be explained
by age of mother, order of birth, or economic factors, and was appar
ently due to factors, probably relating to the physical condition of
the mother, that were associated with interval.
Interval before succeeding pregnancy.— In a small proportion of
cases, those in which the mother became pregnant during the first
year of life of the infant whose history was followed, the commence
ment of a subsequent pregnancy became a factor in the infant’s
chances of survival. Only 4.7 per cent of the total number of
months lived by all the infants, however, were affected by this
factor. The analysis showed that the influence exercised by the
commencement of a subsequent pregnancy was due largely to the
greater prevalence of artificial feeding among these infants; in many
cases probably weaning was advised as soon as the subsequent
pregnancy was known. The fact that a disproportionate number
of these infants were born to mothers of nationalities and in families
in which the father’s earnings were low—groups for which the mor
tality rates were high— also tended to account for their higher
mortality.
Type o f birth.

Premature birth.— The mortality rate for premature infants was
over six times as high as that for infants bom at term. From causes
peculiar to early infancy the greatest difference was found, the rate
for the premature being 25 times that for other infants. The pre
maturely born had an excess mortality from every cause of death.

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Among the factors that contributed to this high excess mortality
among the premature were a disproportionate number of twins and
triplets, a disproportionate number of male infants, and a dispropor
tionate number of babies whose mothers died within one year. 'When
allowance was made for the overweighting of this group with twins
and triplets, with male infants, and with babies whose mothers died—
groups with high death rates— the excess mortality among the
premature was slightly reduced. Another factor was the greater
prevalence of artificial feeding. Nevertheless, when the mortality
among the prematurely bom was compared with that among infants
born at term who received the same type of feeding, the former was
found to be greatly in excess of the latter.
The causes that produce or influence prematurity are referable
largely to the health and condition of the mother. Prematurity was
unusually prevalent among first births, among births to young
mothers, among births following preceding births at short intervals,
and among births to mothers who had been gainfully employed
during pregnancy. The proportion of premature births was also
high among twins and triplets and was higher for male than for female
births.
Plural births.— Among the twins and triplets the mortality from all
causes averaged about three and one-half times, from causes peculiar
to early infancy it was nearly six times, from gastric and intestinal
diseases nearly three times, and from respiratory diseases twice the
corresponding rates for the single-born infants.
This excess mortality among twins and triplets was accounted for
in part by a disproportionate number of prematurely born among
them and in part b y a greater prevalence of artificial feeding. But
neither of these causes accounted for all this excess mortality, since
both among full-term and premature and among breast-fed and
artificially-fed infants the mortality of twins and triplets greatly
exceeded that of single-born infants.
The chances of life of one of a pair of twins were found to be closely
associated with those of the other, partly because twins are likely to
be either both prematurely born or both born at term, partly because
they are more likely to be of the same than of different sexes, partly
because if one is weaned both are likely to be weaned, and for the
rest, doubtless, because both twins are likely to have the same
hereditary advantages and disadvantages and to be subject to the
same favorable or unfavorable environmental conditions.
Type o f delivery.— The mortality rate among infants whose mothers
were delivered by means of instruments (120.3) was considerably
higher than that among other infants (102.1). This difference was
accounted for by a higher mortality from injuries at birth.
Type o f feeding.

The mortality among the exclusively artificially fed averaged
between three and four times that among the exclusively breast fed.
The analysis indicated that early artificial feeding was especially
harmful. The mortality among the artificially-fed relatively to that
among the breast-fed infants was higher the longer the period of
previous artificial feeding; in the first few months immediately fol
lowing the beginning of early artificial feeding the mortality among
96515°— 25t----- 2

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CAUSAL FACTORS IN IN FA N T MORTALITY

the artificially fed tended to increase relatively to that among the
breast fed. The cumulative effect of type of feeding appeared quite
as marked when certain groups which had high mortality^ rates and
in which relatively large proportions of infants were artificially fed—
the prematurely born, the twins and triplets, and the infants whose
mothers died within one year—were excluded from the figures.
When the transition from breast to partly breast or to artificial
feeding was deferred until the eighth or ninth month it was accom
panied not by increasing but rather by decreasing mortality rates.
The excess mortality among the exclusively artificially fed appeared
from every cause of death but was most marked in case o f gastric
and intestinal diseases. The mortality from these diseases among
the exclusively artificially fed was 7.7 times that among the exclu
sively breast fed; from causes peculiar to early infancy the mortality
was 6.1 times, from epidemic and other communicable diseases 2.3
times, and from respiratory diseases 1.8 times the corresponding mor
tality among the breast fed. The high excess mortality from causes
peculiar to early infancy is explained in part by the classification as
due to “ congenital debility” o f deaths from such causes as “ debility,”
“ malnutrition,” and “ marasmus,” which when they occur after the
first month are often the result of faulty feeding. In part, however,
it is the result of a tendency for infants who are physically weak to
be artificially fed in larger numbers than other infants, a tendency
which has been traced in the groups of prematurely born, of twins
and triplets, and of infants whose mothers died within one year.
The excess mortality among the artificially fed was not due to any
overweighting of the group with infants of nationalities for which
the mortality rates were above average, nor was it due to any over
weighting with infants of families in which the fathers’ earnings were
low.
Color 1 and nationality o f mother.

The mortality rates for the several groups of infants classified
according to color and nationality of their mothers were as follows:
Jewish (lowest), 53.5; native white, 93.8; German, 103.1; Italian,
103.8; other foreign born, 129.6; colored,1 154.4; Polish, 157.2;
French-Canadian, 171.3; and Portuguese (highest), 200.3. The
greatest variations were found in the mortality from gastric and
intestinal diseases, the highest rate from which was nearly ten times
the lowest; but, except for one or two shifts in position, the nationali
ties ranked in the same order as when arranged according to their
rates from all causes.
Variations in the proportions of premature births or in the propor
tions of twins and triplets were too slight to affect materially the
relative position of the mortality rates for the several nationality
groups.
Variations in the factors— order of birth, age of mother, interval
since preceding birth, and interval before succeeding pregnancy-—
which together make up the influence of birth rate upon infant mor
tality were also relatively slight and did not suffice to explain the
differences in the rates.
i Throughout this report the term colored is used to include not only Negroes but a small number of
Chinese and Japanese. This is in accordance with the usage of the U. S. Bureau of the Census in its
Birth Statistics and Mortality Statistics.

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The most important differences between the nationality groups
were found in the prevalence of breast and artificial feeding and m
economic status. Each of these factors produced a marked influence
upon the relative rank of the nationalities. The low rate for infants
in the Jewish group was coincident with a high proportion of breast
fed infants and a very low proportion of artificially-fed infants; and
the high rates for infants in the Portuguese and French-Canadian
groups were attended b y low proportions of breast-fed and high pro
portions of artificially-fed infants. On the other hand, the rate for
the native white group was relatively low in spite of a large propor
tion of artificially fed, and that for the Polish group was relatively
high in spite of a low proportion of artificially-fed infants. Differ
ences in economic status helped to explain the favorable position of
the native white and the unfavorable position of the Polish group.
The high mortality among the colored as compared with that among
the native white babies also appeared to be due largely to a compara
tively low economic status. These two factors, it may be noted,
tended partially to offset each other, with the result that after allow
ance was made for both factors together the relative rank of the differ
ent nationalities was not far from their relative rank before such
allowance was made.
Housing congestion.

The infant death rate in families which lived in homes with two or
more persons per room was two and one-half times that in families
which lived in homes with less than one person per room. The
variations in mortality from gastric and intestinal and from respiratory
diseases were especially marked.
Though the group living in congested homes was overweighted
with a slightly disproportionate number of infants of nationalities
which had high death rates and of infants born in families in which
the fathers’ earnings were low, this overweighting was so slight that
when its effect was eliminated the mortality among babies who lived
in the more congested dwellings still appeared markedly above that
prevailing among those who lived in the least congested homes.
Economic factors.

Employment o f mother during pregnancy.— Nearly one-third of the
mothers of live-born infants had been engaged in gainful labor either
at home or away from home during pregnancy; slightly over half
of these had worked at home and the rest— about one-eighth of the
entire group— had worked away from home.
The mortality rate for infants whose mothers had worked away from
home during pregnancy was 176.1, as compared with 114.6 for those
whose mothers had worked at home and with 98 for those whose
mothers had not been gainfully employed. An excess mortality
among the infants whose mothers had worked away from home was
found from each of the principal causes of death and appeared also in
the neonatal mortality rate; the excess was especially great among the
babies whose mothers had no intervals or only short intervals o f rest
from work before confinement. The proportion of premature births
was also highest in the group of infants whose mothers were employed
away from home. Work at home, on the other hand, was accom
panied by a low rate of mortality from causes peculiar to early infancy,
a low neonatal rate, and a low proportion of premature births, as

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compared with the similar figures for the group of infants whose
mothers did not work. It must be borne in mind, however, that the
comparison is not between mothers who worked and mothers who
enjoyed leisure but is rather between mothers who worked at home,
chiefly keeping lodgers, and mothers who did housework. Further
more, the group of mothers who were not employed included those
who but for their poor physical condition would have been at work
either at home or away from home, and consequently this group was
somewhat unfavorably constituted as compared with the others.
The analysis showed that overweighting of the group of infants
whose mothers were employed away from home with babies of
nationalities which had high mortality rates and with babies born in
families in which the fathers’ earnings were low accounted for part
of the high mortality shown b y this group. But even after allow
ance was made for these factors the mortality among infants whose
mothers were employed away from home was 40 per cent higher than
that among infants whose mothers were not so employed.
Employment o f mother during first year o f in f anus life.— Slightly
over one-fourth of the mothers were employed during some part of
the infant’s first year of life, more than seven-tenths of them at home
and less than one-third (or one-twelfth of the entire number) away
from home. Nevertheless, of the months lived to the end of their
first year by all the infants included in the study, only 4.5 per cent
were lived by babies after their mothers had begun work away from
home.
The mortality from all causes among infants whose mothers worked
away from home was two and one-half times, that from gastric and
intestinal diseases was over three times, and that from respiratory
diseases was twice the average rates prevailing at the corresponding
ages; among infants whose mothers worked at home average rates of
mortality prevailed.
The excess mortality among infants whose mothers were employed
away from home was due in part to an unusual prevalence of artificial
feeding, but even after allowance was made for the larger proportion
of artificially fed the mortality among these infants was still twice
the average. Other factors that contributed to the high rate for
infants whose mothers were employed away from home was the dis
proportionate number of babies of nationalities which had high
rates and of babies in families in which the fathers’ earnings were low.
When allowance was made for the former, the rate for the group
employed away from home was still 1.7 times the average, and when
allowance was made for the latter, 1.6 times the average. There
still remained an excess mortality, due probably to lack of the care
which only mothers who remained at nome could give their babies.
Earnings o f father.— The infant mortality rates from all causes and
from each principal cause of death were highest when the father’s
earnings were low and lowest when the father’s earnings were
relatively high. When allowance was made for variations in
the size of the family the same close correspondence was found
between the infant mortality rate and economic pressure as measured
by per capita income from father’s earnings. In general, the father’s
earnings constituted the main source of income of these families, and
the infant mortality rates were lower, family incomes being equal,

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INTRODUCTORY SUM M ARY

when these incomes were derived wholly from the father’s earnings
than when additional funds were derived from the earnings of the
mother or of the older children.
After allowance was made for variations in order of birth, age of
mother, and interval between births, the high correlation between
infant mortality and father’s earnings was still nearly as marked as
before; it could not, therefore, be attributed to association with
unusual frequency of births. Nor could it be explained b y differences
in the prevalence of artificial feeding, for a slightly larger proportion
of infants in the higher than of those in the lower earnings groups
were artificially fed. Furthermore, it could not be explained by
overweighting of the low-earnings groups with disproportionate
numbers of infants of nationalities which had high rates, for the
analysis indicated rather that the high rates in certain of the nationali
ties were to be ascribed to low economic status; the same marked de
crease in infant mortality as father’s earnings increased was found in
each of the principal color and nationality groups. Nor do other
economic factors—housing congestion, employment of mother during
pregnancy, and employment of mother during the infant’s first year—
account for all the relationship between low earnings of father and
infant mortality, though they are responsible for it in part. The
analysis indicated that low earnings of father exerted a potent influence
over the prevalence of these factors and therefore must be regarded as
primarily responsible for the greater mortality associated with them.
The presence of intermediate factors in the chain of causation does
not lessen the responsibility of low earnings as a primary cause.
The intermediate.factors in the chain of causation linking father’s
earnings and infant mortality included, besides those already men
tioned, adequate care of the mother during pregnancy and con
finement and the care of the infant’s health during his first year. A
close association was found to obtain between these factors and the
father’s earnings.

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BASIC M A TE R IA L A N D M E T H O D S O F AN ALYSIS
BASIS OF STUDY

This study is based upon detailed information regarding 22,967
live births and 813 stillbirths 1 which occurred in selected years
between 1911 and 1916 in eight American cities. The cities and
years were Johnstown, Pa. (January 1 to December 31, 1911), Man
chester, N. H. (November 1, 1912, to October 31, 1913), Brockton,
Mass. (November 1, 1912, to October 31, 1913), Saginaw, Mich.
(December 1, 1912, to November 30, 1913), New Bedford, Mass.
(January 1 to December 31, 1913), Waterbury, Conn. (June 1, 1913,
to M ay 31, 1914), Akron, Ohio (July 1, 1912, to June 30, 1914), and
Baltimore, Md. (January 1 to December 31, 1915).
The data secured in regard to each infant included not only facts
available from birth and death certificates—such as sex, whether
single or plural birth, number in order of birth, attendant at birth,
month of birth, age at death, cause of death, legitimacy, race and
country of birth of mother, and age of mother—but information on
other points intimately connected with the infant’s chances of life,
including type of feeding during each month of the first year of life,
period of gestation, mother’s employment during pregnancy and
during the infant’s first year of life, father’s earnings and occupation,
and housing conditions. Facts relating to the mothers’ whole
maternity histories were obtained, from which the interval between
births could be derived; and in one city, Baltimore, details in regard
to the prenatal, confinement, and postnatal care received by the
mothers were sought. In the course of these studies, therefore, a
considerable mass of data has been accumulated covering many
points upon which hitherto much-needed information has been
almost entirely wanting.
The results of the studies of infant mortality in each of these cities
have already been published separately, together with information
relating to the conditions peculiar to each city.2 But in these pre
liminary studies, with the exception of the one relating to Baltimore,
the number of births was too small to justify elaborate analysis.
The accumulation of evidence from all these cities, including the
evidence available for the large number of births in Baltimore, makes
possible the more detailed study of causal influences presented in
this report.
LIMITATIONS OF MATERIAL

The data here analyzed are subject to certain limitations which
must be borne in mind in considering the conclusions drawn.
Since all the births and deaths included occurred in cities, influences
associated with rural as distinguished from those associated with
i Stillbirths are discussed in detail in Appendix A, pp. 167-173.
3 See reports on investigations of infant mortality in Johnstown, Manchester, Waterbury, Brockton,
Saginaw, New Bedford, Akron, and Baltimore (U. S. Children’s Bureau Publications Nos. 9, 20, 29, 37,
62, 68, 72, and 119, respectively).

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urban conditions could not be included in the discussion. In con
sidering the general applicability of the conclusions, therefore, it
must be remembered that they are based upon data limited to urban
areas.
On account of the unusual difficulties encountered in securing
information in regard to illegitimate births, not to mention the fact
that data relating to such births require special analysis, this study is
restricted to legitimate births.3
On some points even the number of births available for the present
study proved too small to afford perfectly satisfactory answers to
the questions raised. In these cases, winch will be noted in the
detailed discussion of each topic, the answer which the information
available does afford is presented as indicating the conclusion which
would probably be more fully substantiated by the addition of more
data.
In other cases, though the number of births is sufficient to afford
definite conclusions in regard to certain important problems, other
questions are raised in the progress of the inquiry to answer which
data are insufficient or entirely wanting. Some of these deficiencies
or gaps in the data available were appreciated more and more fully
as the field studies progressed, and as a result the later studies in
cluded questions on a number of points which in the earlier ones
had been omitted or had not been covered adequately. In a few
cases changes were made in the form of the inquiry or in the details
^of tabulation. On these points, as a consequence, the evidence is
not available in exactly comparable form for all the eight cities,
and the discussion is therefore limited to the group of cities for which
the data are comparable. On some points information is available
for only a single city. These variations in the data will be pointed
out during the progress of the discussion.
Finally, on some important points information is entirely lacking.
In a few cases questions were framed to cover definite aspects of the
relation between a certain factor and infant mortality, but in the
course of the analysis deficiencies in the material became apparent
that precluded a satisfactory treatment of the subject. In other
cases it was not feasible to secure the desired data by the means
available or, as in case of evidence relating to the physical condition
of the mothers during pregnancy, it was impossible at the time the
studies were made to secure full information. In the following dis
cussion, therefore, many questions are raised that still remain to be
studied.
METHODS OF FIELD STUDIES

The methods followed in securing the data have been described in
detail in the reports already issued for each city studied. They
included copying the birth records for the selected year, consulting
the death records to ascertain how many of the infants born in the
selected year had died under 1 year of age, and visiting the mothers
to ascertain other facts in regard to the infants and their environ
ment during their first year of life or such part of it as they lived.
- Difficulties inherent in the procedure of locating mothers and
securing information led to the exclusion of certain cases from the
8 For an analysis of conditions surrounding illegitimate births, see Infant Mortality: Results of a Field
Study in Baltimore, Md., Based on Births in One Year, by Anna Rochester, pp. 155-176 (U. S. Children’s
Bureau Publication No. 119).

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studies; these exclusions, the reasons for them, and their possible
influence upon the mortality rate found for the infants studied as
distinguished from that for all the infants in the city are also fully
described in the several reports.4 Five main groups of infants were
excluded: (1) Illegitimate infants, since as a group they were espe
cially difficult to locate and information in regard to them was not
always obtainable; (2) infants bom to nonresident mothers, who
for the most part came to the city hospitals to take advantage of the
superior facilities for hospital care during confinement and returned
to their homes outside the city shortly afterwards; (3) infants whose
mothers were known to have moved away from the city before the
visit of the agent— cases in which it was not feasible to arrange inter
views with the mothers; (4) infants whose families had moved fr o m
the addresses given on the birth or death certificates and could not
be traced; and (5) infants for whom the necessary data could not be
secured. In short, the excluded cases, though falling into welldefined groups, were all cases for which detailed information could
not easily be obtained from the mothers. Except for the illegitimate
births, the mortality rate for the infants of the excluded groups was
probably not far different from that for the infants included in the
study.
Most of the cities selected for these studies were within the United
States provisional birth-registration area and therefore had fairly
complete registers of births which could be used as the basis of the
study. In two or three cities additional births were located by means
of a canvass, a neighborhood inquiry, or searches through the bap
tismal records of the churches, or by other means. In Akron, a city
which at the time of the study was not in the birth-registration area,
a house-to-house canvass of the entire city was made in order to
complete the list of births. Details of the methods employed to
supplement the original lists of registered births and of the results
obtained are given in the separate reports dealing with,each city.5
METHODS OF ANALYSIS

The infant mortality rates in these studies were arrived at b y com
paring with the number of infants born in a selected year the number
of deaths under 1 year of age that occurred among these infants.
These rates are, therefore, independent of changes in the birth rate
that sometimes affect materially infant mortality rates calculated
by the usual method; that is, by dividing the deaths under 1 year
of age that occur in a given calendar year b y the births that occur
in the same year. Because of this fact they are true infant mor
tality rates; for the purposes of this study, furthermore, the method
followed was the only one feasible for obtaining accurate rates for
the different groups into which the data were to be analyzed.
In consequence of the difference between this method of calcu
lating the rates and that in common use, as well as the policy of exclu
sions, the rates arrived at in these studies for the several cities are
not strictly comparable with those computed b y the ordinary methods
for the same cities; but since the primary object of this study is tor*'
4 See also “ Infant-mortality studies of the Children’s Bureau,” by Robert M . Woodbury, in Quarterly
Publications of the American Statistical Association, Vol. X V I, pp. 30-53.
8 For a summary statement, of these methods and results, together with an analysis of the rates of infant
mortality in the various excluded groups, see Appendix B, pp. 174-183.

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compare the mortality rates for various groups of infants included
in it, the comparability of the rates with those as ordinarily computed
is of minor importance.
The mortality rates used in the present study are of two types:
Those comparing the deaths under 1 year of age within a group with
the births in the same group, thus expressing the probability of
dying within the first year o f life for the infants in the group, and
those comparing the deaths that occurred in a group within a given
month with the number of infants in the group living at the begin
ning of that month, thus expressing the probability of dying within
the given month for the infants in the group. The first^ method
is used whenever the basis of classification is a characteristic of the
births, such as order of birth, prematurity, or age of mother at the
time of the birth. The second is used whenever the basis of classi
fication is a condition subject to change during the first year of life,
such as type of feeding, mother’s employment, or a succeeding preg
nancy of the mother. Since death rates are fundamentally^ a com
parison of deaths with the time lived— the deaths in the time interval
being compared to the total number of the time units lived by infants
exposed to the risk of death 6—it follows that in these cases for which
the basis of classification changes the use of the relatively large unit
of time of one year will not yield a true rate. In the case of the
employment of the mother during the infant’s first year of life, for
example, the death of an infant before the mother went to work can
not be attributed to any effect of the mother’s employment, and to
classify infants simply according to whether or not their mothers
worked at any time in the year will not yield a denominator that
expresses fairly the time lived by the two groups of infants. In order
to obtain accurate results for the relative mortality in such cases,
it is necessary to diminish the unit of time; one month is the most
convenient unit and is short enough so that changes in the infant’s
status occurring within it do not materially affect either the numerator
(the deaths) or the denominator (the timeJived) of the fraction ex
pressing the rate of mortality.
Where two or more causal factors combined to produce a given
result the influence of each was isolated, so far as the data at hand
permitted, by the Westergaard method of expected deaths.7 The
plan of treatment is to consider each factor and separate its influence
from that of other associated factors so that finally a fairly definite
statement can be made in regard to whether the factor under con
sideration has any independent influence upon infant mortality, and,
if so, in regard to the nature and extent of this influence. A question
raised in connection with certain factors is the extent of their influence
over other more immediate causes of infant mortality; in these cases
an effort is made to throw light upon the chain of causation that links
the factor under consideration to the infant mortality rate.
In considering the various causes of infant mortality the subject
of the immediate or pathological cause of death is first taken up.
•The “ probability of dying, ” p, is connected with the death rate, r, by the formula

T .

the use of

the former mode of expressing the rate does not lessen the applicability of the principle stated.
7 For a brief explanation of this method and its application to the problems of infant mortality see Appen
dix O, p. 184. See also “ Westergaard’s method of expected deaths as applied to the study of infant mor
tality,” b y Robert M . Woodbury, in Quarterly Publications of the American Statistical Association,
Vol. X V III, pp. 366-376.

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CAUSAL FACTORS IN IN F A N T MORTALITY

This study suggests underlying physical, social, economic, and other
factors, and the causal influence of each of these is discussed separately
in the succeeding sections of the report.
Age, which has an intimate connection with the incidence of mor
tality, is considered next. A classification by age defines the period
of greatest influence of the various pathological causes of death and is
fundamental to any study of the more complex factors such as type
of feeding.
Seasonal conditions as affecting the chances of life of infants bom
in different months of the year are next discussed. No attempt is
made to study the influence of variations in weather and temperature
conditions for the different cities. Since in each city the births for
a single year were considered, the analysis on this point is limited to
the influence of variations in the temperatures and weather conditions
of the different months of that year.
•
T

able

1 .—

Causes o f death under 1 year o f age; infants in eight cities
Infant deaths

Detailed International
List N um ber

Cause of death

Infant
mortality
Per cent
rates
Num ber distribu
tion

102, 103................ .
104............. ...........
89...........................
91..........................
9 2 ..
. ...... .
150.........................
1 5 1 ( 1 ) - .. ... ... .- .
151(2), 152(2), 153
152(1)...................

All causes_________________________ ____

111.2

2,555

100.0

Gastric and intestinal diseases________________
Diseases of the stomach____ _____ _______
Diarrhea and enteritis........... ...... ...........
Respiratory diseases............. ................................
Acute bronchitis__________ ______ _______
Broncho-pneumonia___________________
Pneumonia_______________ ___________
Malformations_________________. . . . . ____
Early infancy____ ______________ ____ ________
Premature birth_________________ _____
Congenital debility_______________ _______
Injuries at birth__ _____ __________________
Epidemic and other communicable diseases___ 3
Measles._____ ____ ______________________

32.4
1.0
31. 3
19. 6
3. 0
11. 6
4. 9
4.3
36. 1
17. 4
14. 9
3.8
7.1
.5

743
24
719
450
70
267
113
99
830
399
343

29.1
.9
28.1
17.6
2. 7
10.5
4.4
3. 9
32. 5
15. 6
13.4
3.4
6.3
.5

2. 2
.4
.4
.2
.5

51
9
10
5
12

.5
1.0
.1
1. 0
.6
2. 5
8. 7
1.4
2.0
.4
4.9

6............................
7
...... ..
8
.........
9__.........................
Diphtheria and croup____________ 1_______
10...........................
14.... ......... ............
Dysentery______ ______________ _____ ____
18........................ .
Erysipelas_________ ____ _________________
24...... .....................
Tetanus______________________ ....................
28, 29.......... .........
Tuberculosis of the lungs________ . . . . _____
30.
..................... ..................... .....................
31, 32, 33, 34, 35...
Other forms of tuberculosis________________
37
155to 186.” IIIII!
External causes.____ ______ _____ _____ _______
187, 188, 189..........
Diseases ill defined and unknown_____________
6 1 ..
. . . . . . . .........
71............. .............
79.......................... .

Convulsions_____ _______________________
Organic diseases of the heart______________
Other_________________________ __________

162
12

23
3
23
14
58
199
33
45
9
112

2.0
.4
.4
.2

.5
.5
.9
.1
.9
.5
2.3
7.8
1.3

1.8

.4
4.4

* N ot shown when less than one-tenth of 1 per cent.

The influence of sex in the causation of infant mortality is treated
in a separate section.
The remaining factors are treated in six groups. The first group
comprises those associated with the health and condition of thu
mother during pregnancy and at confinement— points on which the
information available in the present study is relatively meager.
This group includes the condition of the mother’s health as indicated

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b y her death in or survival at the end of the year following the child’s
birth, evidence of ill health during pregnancy, and whether or not
she had any medical prenatal care. The mother’s age, which may
be regarded as indicative of her physical maturity or immaturity and
of other physical conditions, is discussed in connection with the second
group, which includes those factors directly associated with birth fre
quency: Order of birth, interval since the last birth, and interval, if
less than one year, before the commencement of the next pregnancy.
The third group comprises factors associated with birth or confinement,
including prematurity, single or plural birth, and type of delivery. A
fourth group is concerned with the various types of feeding. The fifth
comprises the factors connected with the nationality of the mother,
including racial characteristics as to innate vitality or lack of vi
tality and national customs and traditions in regard to feeding,
care at confinement, infant clothing, etc. The sixth and final
group is composed of social and economic factors, including the
mother’s employment or nonemployment during _ the period of
pregnancy and during the first year of the infant’s life, housing con
gestion, and economic status as indicated b y the father’s earnings
and by the per capita income available for the family during the
critical period of the infant’s first year.
Since the infant mortality rate is subject to the influence of many
important factors, the difficulty of isolating the influence of a single
factor is great. In certain cases the analysis by cause of death
simplifies to some extent the problem of tracing the effect of the
particular factor under consideration. For example, the influence
of the mother’s employment during pregnancy would be expected
to appear largely in deaths during the first month of life or in deaths
from causes peculiar to early infancy; on the other hand, the in-*
fluence of the mother’s employment during the first year of the infant s
life would not affect appreciably either of these groups of deaths,
since most of them would have occurred before the mother went
to work. But, in general, the importance of isolating the influence
of one factor from that of an associated factor depends on how close
the association is and how important the associated factor itself is
as a cause of infant mortality. The greater the effect of an asso
ciated factor the more important it is to eliminate its influence from
that of the factor under consideration; and the closer the association
the more essential it is to determine whether the effect ascribed to a
given factor is due indirectly to the associated factor. On the other
hand, if either the effect of the associated factor is slight or the
variations in its prevalence are small, the elimination of its influence
is of minor importance. In this study of causes, therefore, the
procedure of isolating the influence of each causal factor is restricted,
as it must necessarily be with so complex a subject, to the most
important and significant of the associated factors.8
8 For a fuller discussion of the method of analysis see Appendix C, p. 184.

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PATH OLO GICAL CAU SES O F D E ATH

Of the 22,967 live-born infants included in the present study 2,555
died before they were 1 year of age, giving an infant mortality rate
of 111.2.
The causes of death as reported by the physicians who signed the
death certificates are shown in Table 2 classified according to the
International List of Causes of Death.1 In interpreting the results
of this classification it should be borne in mind that their significance
depends upon the accuracy of the original reports of cause made by
the physicians in attendance. The fact that the deaths all occurred
in cities located in States within the death-registration area suggests
that the accuracy of the original returns was probably above the
average for such certification of causes.
The great majority of the deaths fell under the three principal
groups of causes of infant mortality— causes peculiar to early infancy,
gastric and intestinal diseases, and respiratory diseases. The deaths
classified as due to these causes constituted 79.2 per cent, or nearly
four-fifths, of the whole number. Epidemic and other communicable
diseases accounted for a considerable proportion of the remainder.
Each of these groups will be discussed m detail.
CAU SES PECULIAR T O EAR LY IN FA N C Y

The most important group, judging from the proportion of deaths
ascribed to it m the present study, was that of causes peculiar to
early infancy, which comprise premature birth, congenital debility,
and injuries at birth. Together these causes accounted for nearly
one-third of all the infant deaths.
The proportion of deaths ascribed to causes peculiar to early in
fancy depends, however, not only upon the mortality rate from these
causes but also upon the mortality rates from all other causes. This
proportion, therefore, while it indicates the relative contribution of
these causes to the total quota of deaths, is not especially significant
for comparing mortality from these causes among the infants in
cluded in the present study with that among other infants, nor even
for analyzing the relative mortalities within the several classifications
into which the data are subdivided. Even though the rates from
causes peculiar to early infancy were identical in two groups to be
compared, yet the relative proportion of the infant deaths due to this
group of causes would be greater the smaller the number of deaths,
or in other words, the lower the mortality rates, from other causes.
For purposes of comparison, therefore, it is essential to employ specific
infant mortality rates, or deaths from the specific causes per 1,000
live births.

1 In classifying causes which were not stated in the exact terms used in the headings of the table, tlie^
practice of the U. S. Bureau of the Census as given in the Manual of the International List of Causes of
Death and the Index of Joint Causes of Death was followed.

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T

2 . —Comparative infant mortality rates, by cause o f death, in eight cities
studied by the Children’ s Bureau, in cities in the United States birth-registration
area, 1915, and in New Zealand, 1915

able

Infant mortality rates

Cause of death

Eight
American
cities

Cities in
United
States
birth-reg
istration
area, 1915

111.2

103.3

50.1

32.4
19.6
4.3
36.1
7.1
.6
2.5
8.7

26.6
17.8
6.2
35.0
8.5
1.0
.3
8.0

4.9
4.6
4.7
24.9
3.2
.7
.3
6.7

New
Zealand,
1915

The mortality rate from causes peculiar to early infancy was 36.1
and was composed of rates of 17.4 from premature birth, 14.9 from
congenital debility, and 3.8 from injuries at birth. As compared
with similar rates for the cities2 of the United States birth-registra
tion area in 1915 (the earliest year for which such figures are available)
the rate in the eight cities was slightly higher— 36.1 as compared
with 35. The excess appears only in the rate for congenital debility—
which was 14.9 as compared with 11.8. On the other hand, the rate
from premature birth m the eight cities was lower than that in the
citiesof the birth-registration areaof 1915— 17.4 as compared with 18.7.
The rate from injuries at birth was likewise lower— 3.8 as compared
with 4.5. As compared with the 1915 rate from causes peculiar to
early infancy in New Zealand, including both cities and rural areas—
the detailed data not being available for the cities only— the rate
from these causes in the eight cities was almost one and one-half
times as high.
The analysis of the mortality from these causes among the several
groups of infants included in the study revealed marked differences,
which will be taken up in detail in later sections. In passing mention
may be made of the great difference between the rate for infants of
Jewish mothers (22.7) and that for infants of French-Canadian
mothers (44.7) (p. 104). Differences arising from or associated with
employment of the mother during pregnancy, economic status of
the family, race and nationality of the mother, and condition of the
mother during pregnancy and confinement, so far as the facts avail
able in this study throw light upon it, as well as those arising from or
associated with conditions peculiar to the child— whether male or
female, whether twin or triplet or of a single birth— all these differ
ences must be studied if the influences that produce the mortality
from causes peculiar to early infancy are to be traced.
To a large extent these causes have their origin in the condition
d care of the mother during pregnancy and confinement. This is
true especially of deaths from injuries at birth, many of which can
* Including only cities having in 1910 a population of 10,000 and over,

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be prevented b y skilled care. Mortality from premature birth
depends in very large part upon the mother’s condition, though in
art, as will be shown later (b. 73), they depend upon whether the
irths are single or plural. Death from “ congenital debility,” on
the other hand, is in some cases to be ascribed to improper feeding
rather than to prenatal or natal causes, since, in accordance with the
rules for classification followed b y the United States Bureau of the
Census, deaths under 1 year of age from causes stated in such vague
terms as “ marasmus” (wasting), “ emaciation,” “ malnutrition,”
“ debility” — terms which might be used to describe a condition
resulting from improper feeding— are classed with deaths from con
genital debility (pp. 95-96). But with this possible exception the
causes peculiar to early infancy are almost entirely natal ana prenatal
in origin.

GASTRIC AND INTESTINAL DISEASES

Gastric and intestinal diseases, comprising the diseases of the
stomach and diarrhea and enteritis, were second in importance as
causes of death. This group accounted for nearly three-tenths of
all the deaths. Of the diseases included diarrhea and enteritis were
b y far the most important, accounting in fact for nearly all the
deaths from this group of causes.
The infant mortality rate from gastric and intestinal diseases was
32.4: From diseases of the stomach, 1, and from diarrhea and en
teritis, 31.3.3 The rate from these diseases in the eight cities was
considerably above that in the cities of the birth-registration area in
1915 (26.6); the difference appeared wholly in the mortality from
diarrhea and enteritis. The rate from these causes in the eight
cities was over six times as high as the New Zealand rate in 1915
(4.9).
Even more marked differences in mortality from gastric and in
testinal diseases were found between many groups of births in the
eight cities studied— for example, the difference between the rate of
101.6 for infants of Portuguese mothers and that of 10.5 for infants
of Jewish mothers (p. 104). Similar contrasts were shown between
various groups into which the births were classified according to
economic status, mother’s employment, and other factors (pp. 125,132,
141, 148). The difference was especially marked between the mor
tality from these causes among breast-fed infants and that among
artificially-fed infants (pp. 94-96).
These deaths are due largely, in fact, to improper feeding. Not
only the prevalence of artificial feeding itself but also the prevalence
of carelessness in using artificial food and of ignorance as to precau
tions necessary in connection with it vary with nationality tradi
tions, with economic status, and with the employment of the mother.
These points and others that relate to mortality from gastric and
intestinal diseases wdll be discussed in connection with the analyses
of several factors in succeeding.sections of this report.
A markedly high incidence of mortality from gastric and intes
tinal diseases during the summer months is shown in Chart I, which,
gives the distribution of deaths from these diseases by seasons. The
3 Each rate is calculated to the nearest tenth; it sometimes happens, therefore, that the sum of the rates
for two or more groups does not exactly equal the rate for the group into which they are combined.

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high temperatures of the summer months appear to have had a de
cided influence, since three-fourths of all tnese deaths occurred in
the period from July to October (pp. 26, 237). Evidently, therefore,
climatic and weather conditions were an important underlying cause
of mortality from gastric and intestinal diseases.
RESPIRATORY DISEASES

The third _most important group of causes of death was that of
respiratory diseases, comprising acute bronchitis', broncho-pneumonia,
and pneumonia. To these causes were ascribed over one-sixth
(17.6 per cent) of the deaths under 1 year of age.
The infant mortality rate from respiratory diseases was 19.6,
which was composed of rates of 3 from acute bronchitis, 11.6 from
broncho-pneumonia, and 4.9 from pneumonia. These figures were
slightly above those for the cities in the birth-registration area in 1915
which were 2.7, 11.1, and 4, respectively. The mortality from
respiratory diseases in the eight cities was over four times as blah
as the rate for New Zealand in 1915.
The influence of climatic and weather conditions is shown in .the
higher incidence of these diseases during the winter and early spring.
Marked differences were found in the rates for the different race
and nationality groups, which varied from 8.9 for infants of Jewish
mothers to 50.8 for those of Portuguese mothers (p. 104). Differences
m the mortality from these causes which appeared among different
groups in other classifications of the infants in the eight cities will be
discussed in detail in later sections of the report.
EPIDEMIC AND OTHER COMMUNICABLE DISEASES

A subordinate, though important, group, that of epidemic and
other communicable diseases, comprises the principal epidemic
diseases and also tetanus, syphilis, and tuberculosis in its various
forms. This group accounted for about 6 per cent of all the deaths
under 1 year of age in the eight cities.
The infant mortality rate from epidemic and other communicable
diseases was 7.1. Of the individual causes whooping cough took the
largest toll, with a rate of 2.2; tuberculosis ranked second with a rate
•i.1 hari<^ syphilis was third with a rate of 1. Other diseases respon
sible for deaths were measles, erysipelas, diphtheria, influenza,
dysentery, and scarlet fever.
. From this entire group of causes the mortality rate in the eight
cities was slightly lower than that in the cities of the birth-registration
area m 1915— 7.1 as compared with 8.5. From whooping cough
the mortality was higher in the eight cities, but from influenza and
dysentery it was substantially identical, while from all other causes
it was lower than in the cities of the birth-registration area. The
mortality from epidemic and other communicable diseases in New
Zealand m 1915 was less than half that of the eight cities.
Marked differences are to be noted between the rates for the
several nationality and race groups. Thus the rate of 14.9 for infants
of Portuguese mothers was over three and one-half times that for
infants of Polish mothers, 3.9 (p. 104).

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Significant differences were also found between the rates for breast
fed and artificially-fed infants, for the different groups in a classifica
tion based on the earnings of the fathers, and for various other groups
into which the infants were classified. Such differences will be dis
cussed in the sections dealing with these factors.
The epidemic and other communicable diseases are of course due
to specific infections. Variations in the prevalence of mortality
from these diseases depend in part, therefore, upon differences in
the degree to which infants in the several groups are exposed to
infection and in part upon differences in the innate or developed
resistance to these infections among the infants included in such
groups. Hereditary susceptibility has been suggested as a possible
factor in tuberculosis. In cases o f syphilis during infancy the infec
tion has usually been transmitted through the mother to the infant
before birth. Tetanus as a cause of infant mortality is an infection
usually associated with lack of cleanliness at confinement.
The influence of age upon exposure and resistance to epidemic
and other communicable diseases is of special importance. In case
of diphtheria, for example, infants who are breast fed have a
period of immunity that lasts about six months; the incidence of
this disease increases from about the sixth month in case of breast
fed infants until a maximum mortality is reached in the second or
third year of life. The incidence of whooping cough increases from
birth until a maximum is reached and then gradually diminishes,
the heaviest mortality from this disease occurring in the first year.
The incidence of measles increases from birth until a maximum is
reached late in the first or even in the second year. The resistance
of the infant to infection with most of the other diseases, including
tuberculosis, for some reason decreases during the months imme
diately following birth and then gradually increases. As a conse
quence, among the infants included in this study very few deaths
from these diseases occurred in the first month or two after birth.
(See General Table 1, p. 186, and pp. 23-25.)
MALFORMATION 8

The deaths from malformations comprised only 3.9 per cent of the
total number of deaths under 1 year of age. The mortality from
these causes was 4.3 per 1,000 births. Although comparatively little
is known in regard to the specific causes of congenital malformations,
these deaths, like those from causes peculiar to early infancy, have
their origin in prenatal conditions. The rate from malformations
in the eight cities was lower than that in the cities of the birth-regis
tration area or than that in New Zealand in 1915.
OTHER CAUSES

All other causes, comprising principally meningitis, organic dis-.
eases of the heart, convulsions, and ill-defined diseases, accounted
for one-tenth of all the infant deaths. The mortality rate from
these causes was 11.2, which was composed of rates of 2.5 from illdefined and unknown diseases, 2 from convulsions, 1.4 from menin
gitis, 0.4 from organic diseases of the heart, and 4.9 from a miscel
laneous group of other diseases, The corresponding rates for the1
cities of the birth-registration area in 1915, with the exception of

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PATHOLOGICAL CAUSES OF DEATH

that for “ other diseases, ” were lower: From ill-defined and unknown
diseases, 0.3; from convulsions, 1.2; from meningitis, 0.8; and from
organic diseases of the heart, 0.3. The New Zealand rate in the
same year from ill-defined and unknown diseases and that from all
other causes were markedly below the corresponding rates for the
eight cities.
The high mortality from ill-defined or unknown diseases means
that rates from other causes, or at least from certain of them, are
understated, since if the true causes of these deaths from ill-defined
or unknown diseases were known the deaths would be properly
assigned. Hence a comparison of the rates from definite causes in
the eight cities with those in the cities of the birth-registration area
or with those in New Zealand is slightly more favorable to the eight
cities than it would be if the assignment of causes of death had been
as accurate in them as in the other areas.
This is true also of mortality attributed to convulsions, since
convulsions are a symptom rather than a disease. A more accurate
return of the causes of deaths ascribed to convulsions would' result
in an increase in the number of deaths and in the death rates charged
to the diseases actually responsible.
SIGNIFICANCE OF COMPARISONS WITH RATES IN BIRTH-REGISTRA
TION CITIES AND IN NEW ZEALAND

In the preceding discussion the rates of mortality from the several
causes for the eight cities have been compared with those for New
Zealand and for the cities in the birth-registration area of the United
States in 1915. This comparison gives an idea whether the mortality
in the eight cities was relatively high or low and reveals that it was
not only markedly in excess of that attained in the country with the
lowest infant death rate in the world but also considerably in excess
of that in the birth-registration cities of the United States.
The relatively high rates in the eight cities, especially as compared
with those from the same causes in New Zealand, suggest that a
large proportion of the deaths in the eight cities were preventable.
The influence of various conditions upon the infant mortality rate is,
therefore, an important subject of inquiry, which will be taken up in
succeeding sections as far as is permitted by the data available for
analysis.
The fact that rates in the eight cities studied were higher than
those in the cities of the birth-registration area is doubtless to be
accounted for chiefly by the special characteristics of the cities
selected for study. Each of these cities was selected because it
possessed in marked degree some industrial characteristic that would
serve to bring out contrasts in conditions which might affect infant
mortality. Thus Johnstown is a city in which the manufacture of
steel is the principal industry; Manchester is dominated b y its textile
factories; Brockton is a shoe-manufacturing center; Akron is promi
nent in the manufacture of rubber goods; .and Saginaw, New Bed
ford, and Baltimore are cities with diversified industries. Most of
these cities, furthermore, have very considerable proportions of
foreign-born inhabitants, and Baltimore has a very considerable pro
portion of negroes. These characteristics of the eight cities selected
96515°—25t----- 3

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CAUSAL FACTORS IN IN F A N T MORTALITY

for special study probably go far to explain their relatively high
infant mortality rates as compared with those of the birth-registration
cities.
The chief interest of the present analysis of infant mortality in the
eight cities, as already suggested, lies in a comparison of the death
rates for the various groups classified according to special conditions
of birth or of environment during life and in a search for explanations
of the differences found which will throw light upon possibilities of
prevention. The full data available for each of the births included
permit detailed analysis of the causal factors operating to produce
differences in mortahty.

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A G E O F IN F A N T

Mortality among infants under 1 year, it is well known, varies
markedly according to the month of age. The rates for the babies
included in this study were highest immediately after birth, dropped
rapidly during the first two weeks, and continued to fall, though at a
constantly diminishing rate of decrease, throughout the year. If the
mortality which prevailed during the first two weeks had continued
throughout the year, nearly all the infants would have died before
the end of the year. Even if the mortality which prevailed during
the first month had continued, more than half the infants would
have died. Table 3 shows the rates prevailing during each month
of life calculated both upon a monthly and upon a yearly basis, the
latter being 12 times the former. In subsequent discussions
monthly rates 1 are used wherever the data are classified by months
of life.
When deaths from the different causes are considered separately,
as in Table 4, the variations in the rates by age are found to be differ
ent for the several causes. Most of the deaths from malformations
occurred during the first month. The rate from causes peculiar to
early infancy was 30.3 in the first month but fell abruptly to 2.3 in
the second and to a negligible figure in later months. When the mor
tality from causes peculiar to early infancy was analyzed, it appeared
that the deaths from injuries at birth occurred almost without ex
ception in the first month and that of those from premature birth
more than eleven-twelfths took place during the first month. On the
other hand, over one-third of the deaths from congenital debility
occurred after the first month. Further analysis showed that a large
proportion of these infants who died after the first month had been
artificially fed, which suggests that in these cases wrong feeding may
have had more to do with causing death than innate physical weak
ness or lack of vitality (pp. 95-96).
T

able

3 .—

In fant mortality rates, by month o f life; live births in eight cities

Month of life

Monthly Annual
mortality mortality
• rates
rates1

F i r s t ..___ _

Fifth .

44.8
9.3
8.1
8.0
7.7
7.4

538
112
97
96
92
89

Month of life

Seventh_____________ ______
Eighth....................................
Ninth_____________________
Tenth................. .....................
Eleventh.................. ..............
Twelfth_________ __________

Monthly Annual
mortality mortality
rates1
rates
6.3
5.8
5.7
5.3
3.9
4.5

76
70
68
64
47
54

1 If rates for each month continued for 12 months.

Besides malformations and causes peculiar to early infancy, which
in most cases probably had their origin in the prenatal period or at
birth, respiratory diseases appeared to claim a somewhat larger
1 Monthly mortality rates are computed by dividing the deaths in a given month by the number of
infants surviving at the beginning of the month and expressing the result ia terns of deaths per 1,000 infants,
23

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CAUSAL FACTORS IU IN FA N T MORTALITY

proportion of victims in the first month or two than at any later
period. From respiratory diseases the rate was 2.9 in the first
month and 2.1 in the second; a tendency to fall was indicated by the
rate of 1.2 in the eleventh and twelfth months.
On the other hand, the mortality from gastric and intestinal diseases
showed a tendency to increase during the early months of life. The
rate was 3 in the first month and 2.9 in the second; from this point it
rose until a maximum of 3.8 was reached in the sixth month, after
which it gradually decreased to 1.7 and 1.8 in the eleventh and
twelfth months, respectively.
T

able

4 .—

Monthly death rates, by cause o f death and month o f life; infants in eight
cities 1
Monthly death rates from specified causes

Month of life
All
causes

First_______ _____ I___
Second______ _____ _______
Third__________________ _
Fourth......... .................
Fifth____ ________________
Sixth_____________ _____ +_
Seventh_____________ _____
Eighth_________________
Ninth_____________________
Tenth___________________
Eleventh____________________
Twelfth____________________

Gastric Respira
and
Malfor
tory
intestinal diseases
mations
diseases

44.8
9.3
8.1
8.0
7.7
7.4
6.3
5.8
5.7
5.3
3.9
4.5

3.0
2.9
3.7
3.5
3.7
3.8
3.4
2.4
2.3
2. 6
1.7
1.8

2.9
2.1
1.7
2.1
1.5
1.6
1.6
2.0
1. 7
1.4
1.2
1. 2

3.3
.1
.3
.2
.2

Epidemic
Early and other
communi
infancy
cable
diseases

Other
causes

30.3
2.3
.8
.8

1.0
.8
.6
.6

4.2
1.2
.9
.8

J2,

1 For basic figures see General Table 2, p. 187.

In interpreting this increase in gastric and intestinal diseases during
the first few months the question might be raised whether it was due
to an increase in the proportion of infants who were artificially fed (a
group in which the rate from gastric and intestinal diseases was
especially high) or whether it occurred irrespective of any change in
feeding. . This question can be answered by a study of the mortality
from gastric and intestinal diseases among the breast-fed and the
artificially-fed infants from month to month during the early part of
the first year of life. (See General Table 67, p. 212.) For the breast
fed infants the maximum rate of 2.1 was found in the first month;
the rate fell rapidly, to 1.3 in the second, 1. 2 in the third, 0.7 in the
fourth, 0.8 in the fifth, 0.6 in the sixth, and 0.3 in the seventh month.
During this period the groups studied included from 19,000 to 8,000
breast-fed infants. In the months after the seventh the rates showed
a tendency to increase, reaching 1.2 in the eleventh month; but in
these later months the number of breast-fed infants in the groups
studied fell off rapidly to less than 3,000 in the twelfth month.
For the artificially-fed infants, on the other hand, the maximum
mortality was not reached until the third month, the rate rising
from 8.3 in the first to 11.1 in the third, and in each month from the.
second to the seventh the rate was higher than in the first. After
the seventh month, when the rate was 8.9, it fell off rapidly to 2.8
in the twelfth. The increase in mortality from gastric and intestinal
diseases that appeared up to the sixth month was due, then, in part

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AGE OF INFANT

to the transfer of infants from breast to artificial feeding but also
in part to a tendency toward an increase in the mortality from these
causes among the artificially fed to a maximum in the third month.
The rate from the group of epidemic and other communicable
diseases, including tetanus, tuberculosis, and syphilis, was highest
in the first month of life, when it was 1. It decreased to the mini
mum of 0.3 in the sixth and seventh months, from which point it
increased again to 0.8 in the twelfth. This group, however, mcludes
a considerable number of diseases, each of which has its own tendency
to vary with age. Two-thirds of the deaths from syphilis and onefourth of those from erysipelas, it may be noted, occurred in the
first month, but only 1 m 25 of the deaths from the other diseases
included in the group occurred during this period. The rate of
mortality from whooping cough tended to decrease after the fourth
month, while deaths from measles practically all occurred after the
seventh and those from diphtheria were largely concentrated in the
last three months of the first year. (See General Table 1, p. 186.)
The correlation between age and mortality rate is to be ascribed,
doubtless,, to the relationships existing between age, physiological
changes, and the several diseases. Thus the influence of natal and
prenatal causes, and in particular the sudden change of environ
ment at birth, produce an extremely high mortality during the first
few days after birth. The influence of these causes upon the death
rates rapidly disappears, and the infants who survive the first week
or two have in a Sense passed the first crisis in their adjustment to
their new environment. But immediately new dangers arise in the
form of respiratory diseases, feeding difficulties, and epidemic and
other communicable diseases. These dangers are encountered by
many infants before they have developed resistance; and the corre
lation of age with the incidence of these diseases is, therefore, ex
plained largely by its connection with the physiological changes that
produce changes in the infants’ resistance.

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SEASO NAL C O N D ITIO N S

The influence of seasonal conditions upon mortality from certain
diseases has already been touched upon in the discussion of causes of
death. In Table 5 the deaths from each of the principal groups of
causes are classified b y the calendar months in which they occurred.
The table also shows for each of these groups of causes the ratio of
the average daily number of deaths in each month to the average
daily number of deaths during the year.
Not only do differences between summer and winter have an im
portant influence on the incidence of gastric and intestinal and respira
tory diseases, but this very influence shows how important are varia
tions between seasons in different years in producing fluctuations in
infant mortality rates. To some extent the variations here shown in
the mortality from these diseases may have been due to peculiar
conditions existing in the particular cities and years selected for study.
But the data available for this study were not adapted to bring out
differences in mortality in different years, since in each city births
for but a single year were studied.
The differences in the rates according to seasons are most striking
in the case of gastric and intestinal diseases, the maximum monthly
mortality from which was 13 times as great as the minimum. The
maximum occurred in August, the minimum in January. This
“ summer peak” is a familiar characteristic of mortality from these
causes.
T

able

5 .—

Calendar month o f death, hy cause; infant deaths in eight cities
Infant deaths from specified causes

Calendar
month of death

All causes

Gastric and
intestinal
diseases

Respiratory
diseases

Epidemic
Early infancy
and other
and mal
communica
formations
ble diseases

Other causes

Num R atio1 Num R atio1 Num R atio1 Num Ratio1 Num Ratio1 Num
ber
ber
ber
ber
ber
ber Ratio1
January............ .177
February.......... 219
March________ 233
196
April- ............
168
M ay...............
153
June.................
J u ly .-.............. 306
August--.........- 324
September____ 265
October............ 199
November____ 149
December........ 166

81.6
111.7
107.4
93.3
77.4
72.9
141.0
149.3
126.2
91.7
71.0
76.5

15
20
21
19
23
33
163
198
132
69
23
27

23.7
35.0
33.2
31.0
36.4
53.9
257.7
313.1
215.7
109.1
37.6
42.7

58
76
63
53
32
24
19
12
21
28
25
39

152.1
220.7
165.2
143.6
83.9
65.0
49.8
31.5
56.9
73.4
67.8
102.3

56
77
102
86
77
72
82
76
88
73
73
67

70.8
107.8
129.0
112.4
97.4
94.1
103.7
96.1
115.0
92.3
95.4
84.8

21
16
19
' 16
15
6
14
17
9
10
8
11

154.0
129.9
139.3
121.2
110.0
45.5
102.6
124.6
68.2
73.3
60.6
80.6

27
30
28
22
21
18
28
21
15
19
20
22

117.7
144.8
122.1
99.1
91.5
81.1
122.1
91.5
67.6
82.8
90.1
95. S'

1 Ratio of the average daily number of deaths in each month to the average daily number of deaths
throughout the year.
26

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SEASONAL CONDITIONS

The group of respiratory diseases, on the other hand, caused
markedly higher mortality during the winter than during the summer
months. Though the contrast between the seasons was not so great
as in the case of gastric and intestinal diseases, the mortality in
February, when the greatest number of deaths from this cause
occurred, was seven times as high as that in August, when the smallest
number occurred.
Deaths from epidemic and other communicable diseases, which
were relatively few in number, were more prevalent m the late winter
and early spring than in the late autumn and early winter.
The mortality from malformations and causes peculiar to early
infancy showed comparatively slight fluctuations from month to
month during the year. It was highest in March. Since almost all
the deaths from these causes occurred during the first month after
birth, the influence of seasonal conditions was practically inseparable
from the influence associated with month of birth, which may have
included, besides seasonal influences upon the infants, the effects of
variations in the mothers’ health and condition associated with the
season. This subject is discussed in connection with the effect of
month of birth.

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M O N T H OF B IR TH

A question closely allied to the two preceding topics is that of the
influence of month of birth upon infant mortality. To a large extent,
variations in mortality among infants born in the different months
are due to variations in the effect of seasonal influences upon babies
of different ages. Infants born in September, for example, are too
young for the hot weather of that month to produce among them a
heavy mortality from gastric and intestinal diseases, and by the time
summer comes again they are already 8 or 9 months old and have
passed the period when these diseases are most deadly. Infants born
in April, on the other hand, are exposed to the hot weather of the
following summer just at the ages when the gastric and intestinal
diseases appear to cause the heaviest mortality. The month of birth
may therefore be a factor in the infant death rate through the con
nection between calendar month of birth, calendar months of heaviest
mortality, and ages when the incidence is greatest of diseases the
prevalence of which varies with the season.
In addition to influencing mortality through the effect of the seasons
upon deaths from certain causes and at certain ages, month of birth
may influence the infant death rate through the effect of the seasons
upon the health of mothers and thus indirectly upon the vitality of
their babies at birth. It is a well-known fact that morbidity and
mortality rates among adults are lowest in the autumn months,
September, October, and November, and highest in the late winter
and early spring. It might be expected that the favorable or unfavor
able influences which seasonal conditions exert over the health of
expectant mothers would extend to the infants born during or soon
after the periods of the year most healthful or least healthful for
adults. But so far as the mortality during the first month of life is
concerned this indirect influence of the seasons through the mother’s
physical condition can scarcely be distinguished from their direct
influence upon the health of the infant.
The death rates, for each month of life, of the infants born in each
calendar month are presented in Table 6. The mortality in the first
month of life was highest in March and lowest in October, correspond
ing fairly well with the periods of highest and lowest mortality among
adults. Infants born in the four months from January to April had
rates of neonatal mortality markedly above average, and those born
in the three months September, October, and December had rates
markedly below average.
An examination of the death rates for the later months of life
reveals marked variations among the different month-of-birth groups.
Thus of the rates in the third month those for the infants born in May,
June, and July were over twice as high as those for the infants born in
any other month except December; of the rates in the sixth monththose for the infants born in January, February, and March were
markedly higher than those for the infants born in any other month,
28

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M O N TH OF BIRTH

This examination shows, indeed, that the rates in any given month of
life wnre highest for the month-of-birth groups that arrived at that
month of life in the summer season, when the mortality from gastric
and intestinal diseases was greatest.
T a b l e 6.

Monthly death Tates, hy month o f life and calendar month o f birth; infants
in eight cities 1

T otal.......
January..........
February______
March_________
April_____ . . . . . .
M ay. . . a_______
J u n e ...____ ___
July___________
August_________
September_____
October________
November_____
December..........

Eleventh

Tenth

Ninth

Eighth

Seventh

Sixth

Fifth

Fourth

Third

First

Calendar month of
birth

Second

Monthly death rates

44.8

9.3

8.1

8,0

7.7

7.4

6.3

5.8

5.7

5.3

3,9

49.2
46. 6
53. 6
49.1
43.9
42.3
47. 7
42. 6
41.1
37. 4
44. 6
39.1

13.5
5.2
6, 8
4.0
3.4
20.8
11.5
11.8
7. 7
9.0
9.6
7.5

5.7
5.8
3.2
6.3
17.1
13.6
14.2
4.9
5.0
5.9
6.2
8.6

2.9
5.2
5.8
19s 7
12.2
8.8
7.5
7.1
5.6
6.5
8.6
7,1

4.0
8. 7
12.8
15.4
9.4
8.3
3.8
6.0
6.7
7.6
6.9
3.3

11.0
14.1
10.8
9.6
7.1
4.5
4.3
5.5
5.1
8.2
3.5
5.0

14.0
11.3
8.2
4.9
2.4
5.6
3.3
3.3
4.0
5.0
2.9
10.5

8.9
8.4
4.9
1.8
5.4
6.8
5.5
4.5
4.0
3.3
6.4
10.1

4.2
1.8
1.7
4.9
6. 6
5.1
7.7
6.2
5.7
5.6
8.2
10.7

1. 8
3.0
3.9
4.3
3.0
6. 9
4.4
1.1
9.8
6.7
14. 2
4.0

3. 6
1. 2
3. 9
3. 7
6.1
5. 8
2.8
2. 3
5. 2
6. 2
4. 2
1.7

4.5

1.2
2.8
5.5

7.4
4.9
4.1
5.0
7.3
7.6
4.5
2.4

1.1

1 For number of deaths see General Table 3, p. 187.

The heavy mortality from gastric and intestinal diseases in the
summer months appeared, then, to be the dominating influence in the
mortality rates for each of the months of life after the first. This
influence was most marked in the months from the second to the
fourth and was relatively slight in the.later months of the first year
a fact which corresponds with the point already made that the
heaviest mortality from gastric and intestinal diseases was found in
the second, third, and fourth months.
The, effect of seasonal variations in mortality from respiratory
diseases, the incidence of which appeared to be greatest in the first
two months of life, is more difficult to trace in Table 6. A heavy
mortality from these causes doubtless contributed' to the large pro
portion of deaths in the first month of infants born during the winter
and early spring and was perhaps responsible for the high rate in the
second month of infants born in January.
Variations in the mortality among the babies bom in the different
. calendar months, by cause of death, are shown in Table 7. The rate
from gastric and intestinal diseases was lowest for babies born in
August and was markedly below average for those born in September
and October. Infants born in these months escaped the heaviest
incidence of death from gastric and intestinal diseases during their
fnst summer because they were then below the most fatal ages for
these diseases, and by the time their second summer had come they
had passed those ages. The highest rate from gastric and intestinal
diseases was found among babies born in April, who were from 2 to
5 months old during the critical period of the summer. The rates
from these causes were also very high for babies born in January,
February, and June. For some reason they were slightly below
average for babies born in March.

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causal factors in infant mortality

Contrary to what might be expected from the fact, brought out
clearly in Table 5 (p. 26), that the months from January to April
had the highest mortality from respiratory diseases and from the
further fact that the incidence of death from these diseases was
greatest during the first two months of life, the highest rate from
these causes was found among infants bom in July, and the next
highest among infants bom m September. On the other hand,
infants bom in March, and next to them those born in October,
November, and December, had the lowest mortality rates from
respiratory diseases. But the number of deaths from these causes
was not large, and the figures may therefore be subject to consider
able chance variation. It may be that the influence of the seasons
upon the mother’s health, which seemed to find confirmation in the
low neonatal mortality rates among babies horn from September to
December, played a part in the mortality from respiratory diseases
among these babies.
The total effect of these variations in the seasonal and other
influences to which the infants who were born in different months
were subjected is shown in the mortality rates from all causes. The
lowest rates were for babies born in August, September, October,
and December; the highest were for babies born in June, April, and
May. In producing this effect variations in the incidence of death
from gastric and intestinal diseases seem to have been the predomi
nating factor.
T

able

7 .—

Infant mortality rates, by cause o f death and calendar month o f birth;
live births in eight cities 1
Infant mortality rates from specified causes

Calendar month of
birth

Live
births

January____________
February___________
March_____________
April_______________
M ay_______________
June________ .______
July____ ___________
August_____________
September_________
October____________
November________ December__________

1,871
1,828
2,016
1,832
1,845
1,960
2,013
1,949
1,897
1,952
1,861
1,943

All
causes

114.4
111.6
113.1
124.5
115.4
125.5
112.3
98.5
102.8
101.4
112.3
104.0

Gastric
and in
testinal
diseases

39.6
41.0
29.3
42.6
33.1
39.3
27.8
21.5
22.7
24.1
33.3
35.5

1 For number of deaths see General Table 2, p. 187.

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Respira Malfor
tory
diseases mations

19.8
20.8
12.9
19.7
21.7
20.4
24.8
19.0
22.7
17.9
17.7
18.0

5.3
2.7
6.4
4.9
5.4
4.6
5.0
2.1
1.6
4.6
4.3
4.6

Early
infancy

33.7
32.8
44.1
43.7
37.4
38.3
37.3
34.4
34.3
29.7
37.1
30.9

Epidemic
and other
commu
nicable
diseases
5.3
5.5
7.9
4.9
8.7
10.7
5.5
8.7
8.4
7.2
6.4
5.1

Other
causes

10.7
8.8
12.4
8.7
9.2
12.2
11.9
12.8
13.2
17.9
13.4
9.8

SE X O F IN FAN T

In the entire group studied male births preponderated over female
in the ratio of 1,034 to 1,000. This preponderance of male births is
similar to that shown in practically all statistics on this subject.
The infant mortality rate for the male infants (123) was nearly
one-fourth higher than the rate for female infants (99.1). This con
trast, also, is in accordance with the data obtained in other studies of
infant mortality. In the United States birth-registration area in
1915, for example, the mortality rate for male infants was 23 per cent
higher than that for female infants, the rates being 109.9 and 89.4,
respectively.1
This excess mortality among male infants during the first year of
life largely offsets the preponderance of males among all infants bom.
In the group studied the number of boys surviving at the end of the
first year o f life was only slightly greater than the number of girls.
The ratio of boys to girls dropped from 1,034 to 1,000 at birth to
1,006 to 1,000 at the first birthday.
T a b l e 8 .— Infant mortality rates, by cause o f death and sex; live births in eight

cities
Male infants
Cause of death
Deaths

All causes.......................
Gastric and intestinal diseases___
Respiratory diseases___
Malformations______
Early infancy________
Epidemic and other communicable diseases.
External causes_______
Diseases ill defined and unknown.
Other causes.................

Female infants

Infant
mortality Deaths
rates

1,436

123.0

1,119

413
262
56
473
80
10
30
112

35.4
22.4
4.8
40.5

330

.9
2.6

Infant
mortality
rates

29.2

7.3

2.5

The explanation of this excess mortality among male infants is
sometimes offered that male children are larger and heavier at birth
than female children and hence that the difficulty of labor is greater
in the case of male infants. This fact may well explain the heavier
mortality among male infants from causes peculiar to early infancy,,
which appears in the figures of Table 8. Also in line with this ex
planation is the fact that the proportion of premature births was
larger for male than for female infants. Of the male infants 5.4 per
cent were prematurely born as compared with 4.7 per cent of the
female. The excess mortality among the male babies from causes
peculiar to early infancy finds a partial explanation in this slightly
greater proportion of premature births. (See General Table 4, p. 188.)
of the Census/r0m BirtB Statistics>1915>P- 21, and Mortality Statistics, 1915, pp. 31S-242 (TJ. S. Bureau

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CAUSAL FACTORS IN IN FA N T MORTALITY

Among the prematurely born, as well as among the infants born at
term, however, the boys had higher mortality rates than the girls,
as appears in Table 9. Among the full-term infants the rate for the
males was 97.2 as compared with 78.7 for the females; among the
prematurely born the rate fó i the males was 570.7 as compared with
504.7 for the females. The mortality of the males, therefore, ex
ceeded that of the females among the full-term infants by 23.5 per
cent and among the prematurely born by 13.1 per cent; when no
allowance was made for the greater proportion prematurely born
among the male infants, their mortality exceeded that of the female
infants by 24.1 per cent.
T

able

9 .—

Infant mortality rates, by sex and term; live births in eight cities 1
Infant mortality
rates
Term
Male

Female

123.0

99.1

97.2
570.7

78.7
504.7

1 For basic figures see General Table 4, p. 188.

The differences in death rates between the two sexes were not
restricted to rates from causes peculiar to early infancy; the male
infants had higher death rates from practically every cause. Fur
thermore, the higher mortality of males is not due to any tendency
toward an excessive preponderance of males over females in. race
and nationality groups in which the rates were above average, nor to
any such excessive preponderance in the low-income groups, since
the ratio of the sexes at birth did not vary significantly in these
several groups. Nor is the higher mortality from gastric and intes
tinal diseases among males explained by a greater tendency to feed
them artificially; although a slightly larger proportion of the male
infants were artificially led, as indicated by figures for the third,
sixth, and ninth months, the excess was only 1 per cent— too small
to account for the difference in the death rates.2 The factors explain
ing the excess mortality of males must therefore include a certain
difference in physical vitality to the disadvantage of the male sex.
In this connection it is of interest to note that at every age throughout
fife— with the possible exception, in some countries, of a period of a
few years around the ages of 25 to 30— the mortality rate among
males is greater than that among females. But though the difference
in mortality at other ages may perhaps be explained by differences in
occupations and environment, no such explanation will account for
the greater mortality among males in infancy.
2 See General Table 5, p. 188. A 1 per cent greater proportion of male infants artificially fed would have
accounted for a total of 17 deaths in excess of the number expected if the proportion of artificially fed had
been the same as for female infants. On this basis the mortality rate for males would have been 121.5
instead of 123.

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PH YSICAL CO N D ITIO N OF M O T H E R

The data available on the physical condition during pregnancy or
at childbirth of the mothers included in this study are very limited.
Records of complete physical examinations would afford the best
basis for a discussion of the influence exerted b y the mother’s health
upon the chances of life of her child. Because of the particular
character and methods of the field investigations on which this study
is based, it was not feasible to secure such records. These investi
gations were limited to data available on the birth or death certifi
cates or on other records already taken and to information obtained
by interviews with the families. The present report can throw light,
therefore, on only a few questions relating to the influence of the
health of mothers on infant mortality rates.
The only point which bears directly upon the question of the
mother’s physical condition and on which complete data were ob
tained for all cities was whether the mother died during or imme
diately following childbirth or within one year after the birth. Be
sides this, in one city, Baltimore, data wera obtained for a small group
of mothers to the effect that they either had or had previously had
tuberculosis; this information was secured from the records of or
ganizations to which these mothers had applied for treatment, and
the group, therefore, includes only certain tuberculous mothers and
not all. In this city, also, data were obtained from the records of
hospitals and their out-patient departments and from the records of
agencies giving prenatal or confinement care as to certain complica
tions of pregnancy and confinement the influence of which can be re
lated to the mortality among infants born to the mothers concerned.
Other factors, which are treated elsewhere in this report, may have
produced their effect upon infant mortality partlv or wholly through
their effect upon or correlation with the mother’s health and condi
tion during pregnancy. These factors include the mother’s age at
the time of the Birth, order of birth, interval since preceding birth,
the mother’s employment during pregnancy) and the economic status
of the family. These points are discussed elsewhere partly because
their effect in many cases is not confined to the indirect influencing
of the mother’s health and partly because direct evidence connect
ing them with specific items of physical condition was lacking for the
mothers included in the present study.
DEATH OF MOTHER

The number of live-born infants whose mothers died at or during
the year following confinement was only 0.6 per cent of the total num
ber.1 Among these infants a very high mortality prevailed (450 per
1,000 live births), one nearly as high as that for the prematurely
Born and over four times as high as that for babies whose mothers
lived for a year or more after their birth.
1 For data on stillbirths see Appendix A, pp. 167-173.

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CAUSAL FACTORS IN IN F A N T MORTALITY

Of the infants whose mothers died within one month after con
finement— in most cases, probably, from causes connected with preg
nancy or childbirth— a considerably larger proportion failed to live
until their first birthday than of the infants whose mothers died be
tween one month and one year after confinement, the infant mor
tality rates being respectively 607 and 367.
T a b l e 10 .— Mortality rates among infants in eight cities whose mothers died at or

within one year after confinement
Infant deaths from—

Death of mother at or within one year after
confinement

All causes

Live
births

Early infancy

Infant
Infant
Number mortality Number mortality
rates1
rates1
Total.....................................................................

22,967

2,555

111.2

830

36.1

Mother died within one year.... .........., ......................

140
56
79
5
22,827

63
34
29

450.0

36
26
10

257.1

2,492

109.2

794

34.8

Mother survived the year..................... .....................

1 Not shown where base is less than 100.

Causes o f death o f infant.

The excessive mortality among the babies whose mothers died was
due largely to causes peculiar to early infancy. The mortality rate
from these causes for this group of infants was 257.1, or over seven
times as high as the rate which prevailed among other infants (34.8).
Furthermore, it was much higher for the infants whose mothers died
within one month than for those whose mothers died between one
month and one year after confinement (464 as compared with 127).
The death rates from other causes, also, were higher for these infants
than for the others, but the differences between the rates for the two
groups were not so great. Nevertheless, the mortality from gastric
and intestinal diseases among the infants whose mothers died was
over twice as high as among those whose mothers lived. (See General
Table 7, p. 1890
Prematurity.

To a considerable extent the high mortality among the infants
whose mothers died was associated with premature birth, which may
have been caused by the same conditions that resulted in the mothers’
deaths. Of the infants whose mothers died 20 per cent were prema
ture as compared with only 5 per cent of all infants. O f those whose
mothers died within one month after confinement 39 per cent were
premature as compared with 7.6 per cent of those whose mothers died
between one month and one year after confinement. This unusually
high proportion of premature births among infants whose mothers
died within one month after confinement accounts in large part for
the extremely high rate of mortality for this group of babies from
causes peculiar to early infancy. Since, however, all but one of these
prematurely born infants died under the age of 1 year, the mothers’

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PHYSICAL CONDITION OP MOTHER

deaths evidently increased the hazard to the prematurely born even
beyond that associated with prematurity. (See General Table 7,
p. 189.)
Type o f feeding.

As would be expected, artificial feeding was much more prevalent
among infants whose mothers died within one year after confinement
than among those whose mothers survived the year. Of the months
lived by the former from birth up to the end of the ninth month 81.8
per cent were months of artificial feeding as compared with only 24.6
per cent in the case of the latter. (See General Tables 8 and 9,
pp. 189,190.) When all infants who died in the first month were left
out of account (including those who died not fed) it was found that
the mortality among those whose mothers died was 4.2 times that
among all the others. When in this group the mortality among the
former was compared with that among the latter who received the
same type of feeding, the average ratio between the death rates in the
two groups was reduced to 2.5. (See General Table 10, p. 190.)
Evidently differences in type of feeding received by infants who sur
vived the first month account for a considerable part, but not all, of
the higher mortality among children of mothers who died within one
year after confinement.
TUBERCULOSIS OF MOTHER

The number of live births to mothers in Baltimore who were
reported to have or to have had tuberculosis was 96. For reasons
already mentioned, this figure probably understates the true number
of such cases. Of these infants 26 died under the age of 1 year,
giving an infant mortality rate of 270.8, or over two and one-half
times the rate (102) for the other infants in the same city. Among
the infants whose mothers were reported to have had this disease 3
deaths from tuberculosis occurred, in comparison with an expected
number of only 0.1 if the average rate of mortality from tuberculosis
had prevailed lor this group. Not only was the rate from tuberculosis
high, but the rates from all other causes, as shown in Table 11, were
far above those for infants whose mothers were not known to have
had tuberculosis. Though the numbers are small, these differences
suggest that the mother’s having tuberculosis exerts a strong adverse
influence over the chances of life of her baby. (See General Table
11, p. 190.)
T a b l e 11.— Mortality rates among infants in Baltimore whose mothers had had

tuberculosis
Infant deaths from specified causes

Condition of mother

Live
births

All causes

Tuberculosis

Other causes

Infant
Infant
Infant
Number mortality Number mortality Number mortality
rates
rates
rates
Total........................................

10,797

1,117

103.5

1.4

. 1,102

102.1

Tuberculous___________ - ................
Not known to have been tuberculous.................................................

270.8

31.3

239.6

10,701

1,091

102.0

1.1

1,079

100.8

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CAUSAL FACTORS IN IN F A N T MORTALITY

COMPLICATIONS OF PREGNANCY AND CONFINEMENT

In addition to such data as that on tuberculosis, details concerning
complications of pregnancy and confinement afford information on
the health of the mother during this period. The findings of urinaly
sis and of physical examination, and information in regard to
specific toxemias and specific illnesses of pregnancy, would be of
great value in the present study if available; unfortunately data
are at hand on only one such point— whether or not the mother had
convulsions.2
A complication of pregnancy or confinement that is often asso
ciated with a serious condition of the mother is convulsions. Of the
total number of live-born infants in the Baltimore study convulsions
were reported for the mothers of only 42— a number which is doubt
less also a minimum statement. In one-sixth of these cases the
mother died. One-third of the babies born to mothers who had
convulsions were premature. Two-thirds of the premature and
one-fifth of thé full-term babies whose mothers had convulsions died
under 1 year of age, the infant mortality rate for the group as a whole
being 357.1. Seven-tenths of the deaths were from causes peculiar
to early infancy, from which the rate was 261.9. (See General
Table 12, p. 191.)
MEDICAL CARE DURING PREGNANCY

Other things being equal, the quality of care received by the
mothers during pregnancy would be expected to influence the infant
mortality rate. Difficulty is experienced, however, in demonstrating
the influence of prenatal care upon infant mortality because of the
fact that in most groups a much larger proportion of the prospective
mothers who are m poor health than o f those who are in good health
seek the advice of physicians. As a result the group of mothers
who. have had medical prenatal care is overweighted, as compared
with the group of those who have not had such care, with cases of
special physical disability. Only a method of classification, on the
basis of the mother’s health, into groups in each of which the health
of mothers who have had prenatal care will be equal, on an average,
to that of those who have not had it can eliminate this difficulty.
In the present study no such classification could be attempted.
Inquiries in regard to medical prenatal care were made only in Balti
more; and even in that city full data regarding the health and con
dition of the mothers during pregnancy were not Available, and con
sequently the results are strongly influenced by the greater tendency
of mothers who were in poor physical condition to consult physicians.
When the live-born infants included in the Baltimore study were
classified according to whether their mothers had received a minimum
of prenatal care—t. e., had had Urinalyses or had consulted physicians
in regard to their pregnancy— the infant mortality rate was found
to be decidedly higher (113.3) for those whose mothers had no pre
natal care than that (93.8) for those whose mothers had at least this
minimum. An analysis by cause of death shows, however, that the
rates from causes peculiar to early infancy, which Would presumably
be most affected by prenatal care, were practically identical— 37.1
* For data relating to stillbirths see Appendix A, pp. 167-173.

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PHYSICAL CONDITION OF MOTHER

in the former group and 38 in the latter— and that the difference
between the general rates of the two groups was caused primarily
by higher mortality from gastric ana intestinal and respiratory
diseases among the infants whose mothers had received no care from
physicians during pregnancy. This result may indicate that the
mothers who consulted physicians during pregnancy also consulted
physicians promptly when their babies were ill. But so far as pre
natal care is concerned it appears to show merely that the two
groups of mothers were not comparable as to physical condition and
that therefore the information obtained can not be expected to show
the influence of prenatal care on the infant mortality rate. (See Gen
eral Table 13, p. 191.)
SUMMARY

Although, unfortunately, the points upon which definite data were
available are limited, the evidence adduced shows clearly the potent
influence which the health and physical condition of the mothers had
upon the infants’ chances of life. In cases in which the mother
died during the year following confinement— in most cases as a result
of a condition that originated before the infant’s birth— the influence
of the mother’s ill-health appeared in high rates of premature bir^h,
of death within the first month, and of deaths from causes peculiar
to .early infancy. These high rates were especially marked in those
cases in which the mother died at childbirth or within the following
month— almost all from puerperal causes. Of the infants whose
mothers died a very large proportion were artificially fed from birth,
owing chiefly either to the death of the mothers or to health conditions
which prevented them from nursing the children.
The babies whose mothers had or had previously had tuberculosis
and those whose mothers had convulsions during pregnancy or con
finement had higher mortality rates than the other babies.
Other points which may have had a direct connection with the
mother’s health and physical condition are taken up elsewhere.The mortality among babies born to mothers under 20 years of age
was found to be excessive, owing probably to the influence of the
mothers’ physical immaturity (pp. 39-48). First births were subject
to a higher mortality than second or third births— a fact probably due
to or connected in some way with the greater physical strain attend
ing a first labor (p. 48). The mother’s employment away from
home during pregnancy was found associated with markedly high
rates of mortality from causes peculiar to early infancy, of premature
births, and of stillbirths, arising doubtless from the connection between
such employment and the mother’s health (pp. 131-134). There
seems also to have been a close correlation between the father’s
earnings and the amount of skilled care available for the mother
during pregnancy and confinement (pp. 162-163).
The present data afford no clear evidence as to the influence of
prenatal care on infant mortality. Information is available for one
city in regard to consultation of a physician during pregnancy; but
^since, unfortunately, in the absence of general medical care for all
expectant mothers, those who consult physicians are predominantly
those who are forced by their poor physical condition to do so, a
96515°—251----- 4

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CAUSAL FACTORS IN IN F A N T MORTALITY

comparison of this group with that of other mothers affords no clear
evidence of the value of such consultation. Other studies 3 have
proved clearly the importance of prenatal care for expectant mothers,
showing that by means of systematic and general care the mortality
in the first month may be reduced to nearly half its usual proportions
and a decided decrease effected in the rates of stillbirths and of
premature births.
3 Dublin, Louis I.: “ The mortality of early infancy.” Transactions of the Thirteenth Annual Meeting
of the American Child Hygiene Association, 1922, pp. 83-95.
Lobenstine, Ralph W ., M . D .: “ The maternity center association.” Mother and Child, Vol. IV. pp.

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FREQUENCY OF B IR TH S

The present section is devoted to a discussion of those factors—
age of mother, order of birth, interval since preceding birth, and com
mencement of a succeeding pregnancy before the infant has reached
his first birthday— that together make up the influences associated
with the “ birth rate.” A mgh birth rate usually signifies that women
marry young and bear many children, who follow one another at
relatively short intervals. So far as the birth rate exerts an influence
over the general infant mortality rate, it must do so by affecting the
chances of life of each individual child. But with respect to any one
infant no birth rate can be calculated. The influence of the birth
rate upon infant mortality, therefore, except so far as it is dependent
upon other factors, such as the economic status of the family, must
be a joint resultant of the influences of mother’s age, number in
order of birth (or number of preceding births), interval since the last
preceding birth, and interval before the beginning of a succeeding
pregnancy.
AGE OF MOTHER

When the births included in this study were classified according to
the ages of .the mothers, the mortality rates were found to be above
average for the infants of both the youngest and the oldest mothers
(Table 12). For the group of babies whose mothers were under 20
years of age the mortality rate was 135.7. From this point it fell to
103.5 for the babies whose mothers were between 20 and 25, and to
101.4 for those whose mothers were between 25 and 30 years of age.
From this low figure the rate rose to 136.7 for the babies of mothers
who were 40 and over. When the group under 20 was subdivided,'
the mortality rate for the infants of the mothers who were under 18
was found to be 160.3. When the group 40 and over was similarly
subdivided, the mortality rate for the infants of mothers between
40 and 45 was found to be only slightly higher than that for the
infants of mothers between 35 and 40; the rate for the infants of
mothers 45 and over appeared very high, but the number of infants
included in this group was too small to allow any very definite
conclusion to be drawn.
T

able

1 2 .—

Age of mother

TTridftr 18
18-19
20-24_____________
25-29

Infant mortality rates, by age o f mother; live births in eight cities

Live
births

Infant
deaths

Infant
mortality
rates

22,967

2,555

111.2

343
1,241
6; 879
6,618

55
160
753
671

160.3
128.9
109.5
101.4

Age of mother

30-34_____________
35-39
40 and over_____ .
40-44_________
45 and over___
Not reported______

Live
births

4,231
2j fi88
958
914
44
9

Infant
deaths

443
340
131
120
11
2

i Rate based on less than 100 cases.
39

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Infant
mortality
rates
104. 7
12 6. 5
136.7
131.3
1 (250. 0)

CAUSAL FACTORS IN IN FA N T MORTALITY

Causes o f death o f infant.

According to Table 13 the most marked variation by age of mother
occurred in the mortality from causes peculiar to early infancy. The
trend of the rates from these causes was similar to that from all causes.
Thus the rate was highest— 54.3— for infants of mothers under 20
years of age; reached its lowest point— 32.6—for infants of mothers
aged 25 to 29 years; and rose again to 48 for infants of mothers 40
years of age and over.
A similar tendency appeared in the mortality from gastric and
intestinal diseases. In this case the lowest rate fell in the group 30
to 34 years; but all the rates in the groups with mothers from 20 to
34 years of age were markedly below those for the groups with mothers
under 20 or 35 and over.
The figures for other causes, however, did not reveal any tendency
toward high mortality among the infants of the youngest mothers,
and although the rates for the infants of the oldest mothers appeared
to be highest, the trend toward higher mortality among the infants
of older mothers was not so clear nor so definite as that shown in the
rates from causes peculiar to early infancy and from gastric and
intestinal diseases.
T a b l e 13 .— Infant mortality rates, by cause o f infant’s death and age o f mother;

live births in eight cities
Infant deaths from specified causes

Age of mother

Live
births

All causes

Gastric and
intestinal
diseases

Early infancy

Other causes

Infant Num Infant
Infant Num Infant
Num mortality
Num mortality
ber
ber mortality
ber
ber mortality
rates j.
rates 1
rates1
rates1
Total____________ 22,967
Under 20____ ____ _____
20-24____ _____ ________
25-29__________________
30-34_____ ____________
35-39_________________ _
40 and o v e r .,..________
Not reported___ _______

1,584
6,879
6,618
4,231
2,688
958
9

2,555

111.2

743

32.4

830

36.1

982

42.8

215
753
671
443
340
131
2

135.7
109. 5
101.4
104.7
126.5
136.7

62
212
201
121
110
36
1

39.1
30.8
30.4
28.6
40.9
37.6

86
232
216
140
109
46
1

54.3
33.7
32.6
33.1
40.6
48.0

67
309
254
182
121
49

42.3
44.9
38.4
43.0
45.0
51.1

'Not shown where base is less than 100.

Neonatal mortality.

The mortality during the first month of life reflects the differences
in the rates from causes peculiar to early infancy. Thus the highest
rates of neonatal mortality, as Table 14 shows, were found among
infants of mothers under 20 and of mothers 40 years of age and over.1
Order of birth.

A close correlation was found between age of mother and order of
birth, as Table 15 shows. Of the births to mothers under 20 years of
age only one-tenth of 1 per cent were of the orders fifth and later, fon
which the infant mortality rates were above average. Of the
1 For rates for later months of the first year of life see General Table 14, p. 191.

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FREQUENCY OF BIRTHS

births to mothers 40 years of age and over, on the other hand, 85.6
per cent were fifth and later in order. (See General Table 15, p. 192.)
When allowance was made for the interrelation between age of
mother and order of birth, it appeared that co n sid e ra b le part
of the greater mortality among infants of the older mothers was due
to the associated factor of order of birth. In fact, the excess mortality
associated only with mother’s age seemed to be concentrated largely
in the group of infants born to the youngest mothers. (Table 16.)
Nevertheless, that the apparent influence of age of mother was not due
entirely to order of birth was shown clearly when an analysis was made
of the mortality among first births. Obviously in this case neither
order nor interval since preceding birth can affect the comparison.
Yet the mortality rates by age of mother had a trend similar to that
observed when all births were grouped together: The infants of the
youngest and of the oldest mothers had the highest rates and those
of mothers of intermediate ages the lowest. (Table 17.)
T

able

1 4 .—

Neonatal mortality rates, by age o f mother; live births in eight cities
Deaths Neonatal
under 1 mortality
month
rates

Live
births

Age of mother

Total_______

22,967

1,028

44.8

tinder 20________
20-24__________
25-29_____________

1,584
6,879
6,618

100
299
278

63.1
43.5
42.0

able

1 5 .—

Age of mother

30-34 _. .
35-39......................

Live
births

Deaths Neonatal
under 1 mortality
month
rates

4,231
2,688

135

50.2
54.3

Proportion o f births fifth and later in order, by age o f mother; live
births in eight cities 1
Live births

Live births

Fifth and later in
order

Age of mother
Total

Number Per cent3
T o ta l...........

22,967

5,974

Ik 0

Under 20 ...............
20-24.................... .
25-29......................

1,584
6,879
6,618

2
178
1,198

.1
2.6
.18.1

1 For basic figures see General Table 15, p. 192.
3Not shown where base is less than 100.

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Fifth and later in
order
Number Per cent3

30-34....... ...............
35-39....................
40 and over_______
Not reported______

4,231
2,688
958
9

1,930
1,842
820
4

45.6
68.5
85.6

42
T

CAUSAL FACTORS IN IN F A N T MORTALITY

16.
Relative mortality, by age o f mother, when influences o f order o f birth
interval since preceding birth and both factors together are eliminated; live births
m eight cities and single live births in Baltimore

able

Ratio of actual to expected infant deathsi
Eight cities
Age of mother

Baltimore

Eliminat
Eliminating ing both
Eliminating On basis of influence of influence of
On basis of influence of average rate interval
interval
average rate order of
for single since pre since pre
ceding
birth
live births
ceding
birth and
birth
order of
birth

Total.................
Under 2 0 ..............
20-24________
25-29..........
3 0 -3 4 ....____
35-39____ _____
40 and over......... .

100.0

122.0

124.9
98.7
85.6
91.8
124.7
121.3

135.7
97.4
85. (5
93. 7
127.6
127.5

156.4
108.6
90.1
91.2
109.3
93.2

2
____

113.8
122.9

i For basic figures see General Table 16, p. 192.
T

able

17.

Infant mortality rates, by age of mother and order of birth; live births
in eight cities
Infant mortality rates1

Order of birth

Age of mother
Total
Under 20

20-24

25-29

30-34

35-39

Total............

111.2

135.7

109.3

101.4

104.7

126.5

First_____
Second.............
Third
Fourth___
Fifth....... .
Sixth_____
Seventh.......
E ighth...........
Ninth............
Tenth and later. .

104.7
95.7
104.6
108.8
118.8
122.7
136.8
135.9
146.8
181.5

125.5
167.2

100.5
105.6
125.0
155.3
97.7

90.4
74.0
103.8
99.7
136.2
150.4
195.7

102.8
76.8
82.1
106.6
96.7
102.1
121.8
137.2
174.6
228.1

131.6
112.7
73.1
82.1
127.5
128.8
131.3
. 121.1
133.9
193.6

40 and
over
136.7

108.9
159.6

1 Not shown where base is less than 100.

Interval since preceding birth.

The interval since the preceding birth must also be considered in
relation to the mother s age. Of the births second and later in order
T h - ^ 20 I ears
a£e; a much larger proportion were
^ort-m tervai births than of similar births to older mothers, as
11 ■ 1 1.8 ®hoJws* xS¥?ce the short-mterval births were associated with
a nigh infant mortality rate, as will be discussed more at length in a
later section,* the high mortality, especially among births second and
later m order to mothers under 20 years of age, may have been due
m part to the influence of the short interval.
7
* For definition and d-iscussion of interval since preceding birth see pp. 60-67.

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FREQUENCY OF BIRTHS

When allowance was made for this correlation of age of mother
and interval between births, the excess mortality ampng infants of
mothers under 20 years of age appeared, in fact, to be slightly re
duced. And when allowance was made not only for the correlation
between age of mother and interval between births but also for that
between each of these factors and order of birth, the influence of age
of mother appeared to be shown almost wholly in a high mortality
rate among infants of the youngest mothers. (See Text Table 16
and General Tables 17 and 18, pp. 42, 193, 194.)
T

able

1 8 .—

Proportion o f short-interval births,1 by age of mother; single live births
in Baltimore second and later in order 2
Live births second and later in
order—

Age of mother
Total

Following preced
ing births at short
intervals1

Live births second and later in
order—
Age of mother
Total

Number Per cent3
Tdtal.............

7,707

2,026

26.3

Under 20...............
20-24_____________
25-29........................

238
1,849
2,385

142
703
592

59.7
38.0
24.8

Following preced
ing births at short
intervals 8
Number Per cent8

30-34....... ................
35-39................. .
40 and over_______
Not reported....... .

1,728
1,111
392
4

356
187
45
1

20.6
16.8
11.5

1 For definition of interval see p. 60.
8 For basic figures see General Table 17, p. 193.
8 Not shown where base is less than 50.

Prematurity.

A markedly larger proportion of premature births was found for
births to the younger than for those to older mothers. According
to Table 19 the proportion decreased from 8.6 per cent among the
births to mothers under 20 to a minimum of 4.1 per cent among
those to mothers from 35 to 39 and then rose again to 4.8 per cent
among those to mothers 40 years of age and over.3
The larger proportion of premature births to mothers under 20
years of age tends to account in part for the higher mortality from causes
peculiar to early infancy among the babies born to these mothers.
Perhaps the same fundamental factors that produce a high mortality
from these causes—which have their origin largely in the care and
condition of the mother during pregnancy and confinement— produce
also a high proportion of premature births. Even after allowance
was made for the greater prevalence of premature births, the mor
tality from causes peculiar to early infancy was much higher among
the infants of the youngest mothers than among the infants of
mothers of the next age group, 20 to 24 years.
8 General Table 19 shows that this greater prevalence of premature births to young mothers was in part,
at least, independent of the greater prevalence of premature among first births (p. 194).

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44
T

CATJSAL FACTORS IN IN FA N T MORTALITY

able

1 9 .—

Proportion of premature births, by age o f mother; live births in eight
cities
Live births

Live births

Premature

Age of mother

Total

Number Per cent1

20-24
25-29_____________

Premature

Total

22,967

1,158

5.0

30-34........................

4,231

1,584
6,879
6,618

137
368
314

8.6
5.3
4.7

40 and over_______
Not reported______

’ 958
9

182
lift
46
1

4.3
4.8

1Not shown where hase is less than 100.

Plural births.
In contrast to the greater prevalence of premature births to the
youngest mothers, a markedly larger proportion of the infants born
to older mothers than of those to younger mothers were twins and
and triplets. (Table 20.) Other things being equal, the fact that
plural births occurred more frequently to the older mothers would
tend to produce a slightly higher average mortality among the
infants o f the older mothers. The influence of this tendency, how
ever, is relatively slight. The trend of the mortality rates is prac
tically the same for the single births as for all births, although the
mortality among the infants of the youngest mothers appears rela
tively slightly greater and that among the infants o f the oldest
mothers relatively slightly less for single births than for all births.
(Table 21.)
T

able

2 0 .—

Proportion o f plural births, by age o f mother; live births in eight cities
Live births

Live births
Age of mother

Plural

Age of mother
Total

20-24____' _______
25-29........................
T

able

2 1 .—

Plural
Total

Number

Per 1,000

22,967

529

23.0

30-34....... ................

4,231

124

29. 3

1,584
6|879
6,618

13
124
161

8.2
18.0
24.3

40 and over_______
Not reported______

958
9

26.1

Number Per 1,000

Relative infant mortality rates, by age o f mother, fo r single births and
for all births; live births in eight cities
Infant mortality rates
All births

Age of mother
Rate

Single-births

Ratio
to
aver
age
rate
(per
cent)

Rate

Ratio
to
aver
age
rate
(per
cent)

T ota l............ .

111.2

100.0

105.3

100.0

Under 20___________
20-24____ ____ ______

135.7
109.5

122.0
98.5

131.1
103.5

124. 5
98.3

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Infant mortality rates
All births

Rate

Ratio
to
aver
age
rate
(per
cent)-

101.4
104.7
126.5
136.7

91.2
94.2
113.8
122.9

95.9
98.1
120.5
128.6

91.1
93.2
114.4
122.1

Age of mother

25-29______________
30-34______________
35-39______________
40 and over________

Single births

Ratio
to
aver
age
rate
(per
cent)

FREQUENCY OP BIRTHS

Type o f feeding.

The prevalence of artificial feeding appears to have varied with
the age of the mother. (See General Table 22, p. 195.) Of infants
surviving at the beginning of the third month, for example, those
bom to mothers 40 years of age and over had the largest proportion
(27.8 per cent) and those born to mothers from 25 to 29 years of age
had the smallest proportion (18.8 per cent) artificially fed. The
proportion artificially fed of infants of the youngest mothers (20;5
per cent) was only slightly above that of infants of mothers from 25
to 29 years of age. By the time the ninth month was reached these
differences in the prevalence of artificial feeding had largely dis
appeared. The highest percentages of infants surviving at the
beginning of the ninth month who were artificially fed were found
for the infants of the youngest mothers— 36.9 per cent for the age
group under 20 and 36.2 per cent for the group from 20 to 24—hut
these percentages were only slightly higher than the figure (36) for
the age group 40 and over; the lowest percentage (33.1), was that
of the infants of mothers 30 to 34 years of age. Except for the high
percentage of infants wrho were artificially fed during the early months
of life in the age-of-mother group 40 years and over, these differences
in the prevalence of artificial feeding must be considered relatively
slight when measured in terms of the influence which such differences
might have upon the infant mortality rates in the several groups.
The prevalence of artificial feeding among the infants of
mothers 40 years of age and over accounts in part for the excess
mortality of this group. If the same proportion of these infants had
been artificially fed as of the infants of mothers between 25 and 30
years of age, the mortality rate for the group would have been only
125.7 instead of 136.7. (Thus reduced, it would still have been
higher than the rates for any except infants of the youngest mothers.)
The greater prevalence of artificial feeding among infants of
mothers of the older age groups appeared, as Table 22 shows, to be
connected with the age factor and to be independent, in part at least,
of order of birth. The numbers artificially fed among infants of
mothers 30 years of age and over were considerably greater than
would have been expected on the basis of the proportions artificially
fed among all "births of the corresponding orders.
T

2 2 . — Influence o f age o f mother upon, the proportion o f infants artificially
fed during the third month o f life , when ihfiuenbe o f order o f birth is eliminated;
infants in eight cities

able

Infants surviving at
beginning of third month

Infants surviving at
beginning of third month
Age of mother

Actual Expected Ratio of
number number actual to
artifi
artifi
expected
cially
(per
cially
cent)
fed i
fed

Age of mother

Total.

4,431

4,430.8

100.0

30-34...................... .

Under 20...
20-24__i___
25-29.— .

301
1,291
1,184

310.1
1.327.8
1.239.9

97.1
97.2
95.5

40 and ov er............
Not reported..........

Actual Expected Ratio of
number number actual to
artifi
artifi
expected
(per
cially
cially
cent)
. fed
fed i

1 Expected at average proportions artificially fed in each order-of-birth group.

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836
. 569
249
1

799.7
536.4
215.3
1.6

104.5
106.1
115.7
62.5

CAUSAL FACTORS IN IN FA N T MORTALITY

Color and nationality o f mother.

According to Table 23, a considerably larger proportion of the
infants bom to mothers 40 years of age and over than of those born
to mothers nnder 20 were of race or nationality groups which had
higher than average infant mortality rates— 37.9 per cent as com
pared with 23.5 per cent. In part, therefore, the higher mortality of
the babies bom to the older mothers may have been due to factors
associated with nationality rather than to those associated with the
mother’s age.
The extent of the influence of the correlation between age of mother
and nationality was comparatively slight, however. When allowance
was made in Table 24 for this interrelation the mortality of babies of
the oldest relatively to that of babies of the youngest mothers ap
peared slightly lower than before the correction was made, but other
wise the trend of the mortality rates b y age of mother did not appear
to have been materially altered.
T

able

2 3 . —-Proportion

o f births to mothers o f nationalities with high infant mor
tality rates, by age o f mother; live births in eight cities
Live births—

Live births—
T o mothers of na
tionalities with
high infant mor
tality rates1

Age of mother
Total

Number

T o mothers of na
tionalities with
high infant mor
tality rates1

Age of mother
Total

Number

Per cent

Total.............

22,967

7,428

32.3

Under 20............... 20-24.......................
25-29..............- ........

1,584
6,879
6,618

373
1,999
2,182

23.5
29.1
33.0

30-34,....................
35-39.......... ............
40 and over______
Not reported.......

4,231
2,688
958
9

Per cent

1,490
1,013
363
8

35.2
37.7
37.9

i includes French-Canadian, Polish, Portuguese, “ other foreign born,” and colored. For basic figures
see General Table 23, p. 195.
T

able

2 4 .—

Relative mortality, by age o f mother, when influence o f nationality o f
mother is eliminated; live births in eight cities
Infant deaths

Infant deaths

Age of mother
Actual

25-29.____________

Ex
pected *

Ratio of
actual to
expected
(per
cent) 3

Age of mother
Actual

2,555

2,555.1

100.0

30-34.......................

215
753
671

171.9
756.5
735.7

125.1
99.5
91.2

40 and over.............
Not reported...........

443
340
131
2

Ratio of
actual to
Ex
expected
pected i
(per
cent)3
473.3
305.3
111.1
1.3

93.6
111.4
117.9

i Expected at average rates for each color and nationality group irrespective of age of mother.
* Not shown where base is less than 100.

Earnings o f father.

A larger proportion of births to mothers under 20 years of age (54.7'
per cent) than of births to mothers of any other age group occurred
m families in which the fathers earned less than $650. The contrast
is even more marked when first births and later births are considered

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FREQUENCY OP BIRTHS

separately. According to Table 25, of first births to mothers under
20, 51.8 per cent occurred in families in which the father’s earnings
were less than $650, as compared with half as large a proportion of
first births to mothers 25 and over. In other words, in the higherearnings groups the mothers were older at the time of the first births.
Of second and later births to mothers under 20, 64.4 per cent occurred
in the low-income group, as compared with approximately two-thirds
as large a proportion of second and later births to mothers 25 and over.
When allowance was made for this interrelation between father’s
earnings and age of mother, the excess mortality among the births to
the youngest mothers was somewhat further reduced, as Table 26
shows.
T

able

2 5 . — Proportion o f births in fam ilies in which the father earned less than
$650, by age o f mother and order o f birth; live births in seven cities 1

Live births
First
Age of mother
Total

In families in
which father
earned less
than $650
Total

Total............................. 21,536
Under 20___________ ____
20-24.......................
25-29...................
30-34.............................
35-39.....................
40 and over__________
Not reported_______ _____

1,503
6,434
6,236
3,962
2,508
884
9

Second and later

In families in
which father
earned less
than $650

Num
ber

Per
cent a

9,133

42.4

5,908

2,157

36.5

822
2,823
2,415
1,563
1,104
399
7

54.7
43.9
38.7
39.4
44.0
45.1

1,160
2,949
1,295
377
111
14
2

601
1,099
326
97
28
5
1

51.8
37.3
25.2
25.7
25.2

Num
ber

In families in
which father
earned less
than $650

Total

Per
cent2

Num
ber

Per
cent2

15,628

6,976

44.6

343
3,485
4,941
3,585
2,397
870
7

221
1,724
2,089
1,466
1,076
394
6

64.4
49.5
42.3
40.9
44.9
45.3

1 For basic figures see General Table 24, p. 196.
* Not shown where base is less than 50.
T

able

2 6 .—

Relative mortality, by age o f mother, when influence o f earnings of
father is eliminated; live births in seven cities
Infant deaths

Age of mother

Total____ _
Under 20.................
20-24..........................
25-29....................... .

Infant deaths

Actual

Expect
ed 1

Ratio of
actual to
expected
(per cent)

2,368

2,367.6

100.0

206
699
619

179.3
717.3
670.8

114.9
97.4
. 92.3

Age of mother
Expect
ed 1

Ratio of
actual to
expected
(per cent)

404

422.6

95.6

Actual

30-34.....................■*

120.7

1Expected at average rates for each earnings-of-father group irrespective of age of mother.

Summary.

Among the first births age of mother appeared to influence mor
tality in such a way that the infants of the youngest and of the oldest
mothers— those under 20 and those 40 years of age and over—had
the highest rates.

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CAUSAL FACTORS IN IN F A N T MORTALITY

Of births second and later in order, those to mothers under 20 years
of age had the highest rate of mortality, owing in part to short inter
vals since preceding births, in part to the greater prevalence of pre
mature births, and in part to the relatively low economic status o f the
families in which the infants were born, but also, apparently, in part
to some factor associated with the mothers’ age. The high mortality
that appeared among infants born to the oldest mothers seems to
have been due largely, if not wholly, to other factors than age— order
of birth, plural birth, and prevalence of artificial feedings—since a
larger proportion of these than of infants born to younger mothers
were of late orders or were twins or triplets, and a slightly larger
proportion of them were artificially fed.
ORDER OF BIRTH

When the live births were classified by order4 the infant mor
tality rates, after an initial drop from the first to the second birth,
increased steadily with the order o f birth, as Table 27 shows. The
rate for first births was 104.6 and for second births 95.7; rates for
the later orders rose rapidly, reaching the maximum of 181.5 for
births of orders tenth and later. The tendency for the rate for first
births to be slightly higher than that for second and for the rate to
rise rapidly for the later orders is characteristic and is found in other
statistics.5 The infant mortality rates for orders under the fifth
were below the average for all births, and those for orders fifth and
later were above the average.
T a b l e 27 .— Infant mortality rates, by cause o f death and order o f birth; live births in

eight cities
Infant deaths from specified causes

All causes
Order of
birth

Live
births

Gastric
and
intestinal
diseases

Respiratory
diseases

Early
infancy

Epidemic
and other
communi
cable
diseases

Other
causes

Infant
Infant
Infant
Infant
Infant
Infant
Num mor Num mor Num mor Num mor Num mor Num mor
ber tality ber tality ber tality ber tality ber tality ber tality
rates
rates
rates
rates
rates
rates
111.2

743

32.4

450

19.6

830

36.1

162

7.1

370

16.1

652 104.6
474
95.7
348 104.6
270 108.*8
210 118.8
155 122.7
126 136.8
92 135.9
69 146.8

155
138
92
82
65
56
44
33
20

24.9
27.9
27.6
33.1
36.8
44.3
47.8
48.7
42.6

79
87
67
68
47
25
24
17
11

12.7
17.6
20.1
27.4
26.6
19.8
26. 1
25.1
23.4

259
152
119
69
60
44
31
27
22

41.6
30.7
35.8
27.8
34.0
34.8
33.7
39.9
46.8

43
26
23
15
9
11
8
7
9

6.9
5.2
6.9
6.0
5.1
8.7
8.7
10.3
19.1

116
71
47
36
29
19
19
8
7

18.6
14.3
14.1
14.5
16.4
15.0
20.6
11.8
14.9

181.5

66.2

28.5

53.7

12.6

20.5

Total— 22,967 2,555
First________
Second____ _
Third. _____
Fourth____ _
F ifth .!______
Sixth____. . .
Seventh_____
Eighth______
Ninth_______
T e n t h and
later...........

6,230
4,954
3, 328
2,481
1, 767
1,263
921
677
470
876

159

*In determining classification the order of a birth was taken as one more than the number of previous
births, including stillbirths (dead births of at least seven months’ gestation) and in the case of births studies'
in Baltimore, or nearly half of those now under consideration, including also miscarriages. In the cases
of twins or triplets both or all were classified as of the same order of birth.
'See, for example, Die Lehre von der Mortalität und Morbilität, by H. Westergaard (Second Edition),
p. 364 (Jena, 1901).

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FREQUENCY OF BIRTHS

Causes o f death.

A marked contrast in the trend of the infant mortality rates for
the several orders appears in Table 27 between causes peculiar to
early infancy and the two other major groups, gastric and intestinal
and respiratory diseases. The mortality rate from causes peculiar
to early infancy was especially high for first births— 41.6 as compared
with an average of 32.3 for births of orders second to seventh; only
the ninth and the tenth and later orders had higher rates from these
causes than the first. On the other hand, the rate of mortality from
gastric and intestinal diseases was lower for first births than for any
later order; this was true also of the rate from respiratory diseases.
Evidently, therefore, the tendency for the first births to have a
higher rate of mortality from all causes than the second births was
due to their markedly less favorable rate from causes peculiar to
early infancy, offset in part by their slightly more favorable rates fr o m
gastric and intestinal and from respiratory diseases.
Neonatal mortality.

The mortality during the first month was much higher among
first births than among those of any other order up to the group
tenth and later. (Table 28.) This trend follows closely that of the
rates from causes peculiar to early infancy, a group of causes which
contributed the bulk of the deaths during the first month.6
T a b l e 28 .— Neonatal mortality rates, by order o f birth;- live births in eight cities

Order of birth

Live
births

Deaths Neonatal
under 1 mortality
month
rates

Total_______

22,967

1,028

44.8

First......... __...........
Second________ __
Third_____ ______
Fourth__________

6,230
4,954
3,328
2,481

334
194
138
89

53.6
39.2
41. 5
35.9

Order of birth

Fifth...

Tenth and later....

Live
births

Deaths Neonatal
under 1 mortality
month
rates

1,767

921
677
470
876

37
33
22
60

4Ä 7
68! 5

Age o f mother.

The order of birth is, of course, closely related to the age of the
mother. Seven-tenths of the first births but none of those tenth or
later in order were to mothers under 25 years of age. On the other
hand, only 8.5 per cent of the first births but 56.9 per cent of the
fifth births and 99 per cent of the births tenth or later in order were
to mothers 30 years of age or over. (See General Table 15, p. 192.)
It has already been shown that the mortality rates were higher
than average for infants of mothers under 20. Therefore the high
proportion of infants of young mothers in the group of first births
would tend to account for the high mortality rate for these births;
but this tendency was in part offset by the low proportion among
first births of infants of mothers 35 years of age and over, for whom
also mortality rates were high. Similarly, the high proportion in
the group of births tenth and later in order, of infants o f mothers
35 years of age and over would tend to account for the high mortality
rate for these births, but this influence was in part offset by a low
proportion in this group of births to mothers under 20 years of age.
6 For monthly death rates in later months see General Table 26, p. 197.

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CAUSAL FACTORS IN IN F A N T MORTALITY

The variation in the percentages of births to mothers of ages asso
ciated with higher than average infant mortality rates is shown in
Table 29 for each order of birth.
T

able

2 9 .—

Proportion o f births to mothers under 20 and to those 85 years of age
and over, by order o f birth; live births in eight cities
Live births

Live birthsTo mothers under
'20, and 35 years
and over

Order of birth
Total

Total_______

22,967

Fourth.................

6,230
4,954
3,328
2,481

To mothers under
20, and 35 years
and over

Order of birth
Total

Number Per cent

Number

POT cent i

5,230

22.8

Fifth....................

1,355 ;
537
344
330

21.7
10.8
10.3
13. 3

Seventh_________ _
E ighth...___ ____
Ninth____________
Tenth and later___

1,767
Ï, 263
921
677
470
876

377
411
421
380
322
753

21.3
32.5
45.7
56.1
68.5
86.0

The infant mortality rates shown in Table 17, b y order of birth for
each age-of-mother group, indicate that the influence of order varied
with the age of the mother. Of births to mothers under 20 years of
age, the rate was lowest for first and rose rapidly for second and
third. Comparatively few infants of orders later than third were
found in this group for obvious reasons. Even when two or three
babies had been born to one of these very young mothers the intervals
between them were usually short. Of births to mothers between 25
and 30 years of age, on the other hand, the rate for the first, while
lower than that for the first infants of mothers under 20, was still
considerably higher than the rates for the second and the third; the
mortality increased with the orders and therefore with the probability
of short interval. Of births to mothers 35 years of age and over the
rate was markedly high for the first— almost as high as that for the
first infants of mothers under 20—fell to a minimum for the third
and fourth births, and rose for later orders.
When allowance was made for the interrelation between order of
birth and age of mother, as the comparison given in Table 30 indi
cates, first births had a higher mortality than second, and the rate
rose from second to tenth and later— but at a slightly less rapid rate
of increase than when no allowance was made for age of mother.
T a b l e 3 0 . — Relative mortality, by order o f birth, when influence of age o f mother is

eliminated; live births in eight cities
Infant deaths

Infant deaths

Order of birth

Ratio of
Ratio of original
rpte to
actual average
Ex
to ex
(per
Actual pected1 pected
cent)
(per
cent)
2,555 2,555.1

Fourth..._______

652
474
348
270

703.9
538. 7
356.9
266.3

Order of birth

Ratio of
actual
Ex
to ex
Actual pected1
pected
(per
cent)

100.0

Fifth................

210

192.8

108.9

92.6
88.0
97.5
101.4

94.2
86.1
94.2
97.8

Seventh....... ......
Eighth...............
N inth_________
Tenth and later.

126
92
69
159

106.3
79.9
57.2
111. 9

118.5
115.1
120.6
142.1

l ¡Expected at average r^t§s for births in e^?h age-of-mother group, irrespective of order of birth.

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Ratio of
original
rate to
average
(per
cent)

106.8
110.3
123!“
122.2

132.0
163.2

FREQUENCY OF BIRTHS

Interval since preceding birth.

The proportion of births following preceding-births at short inter
vals is shown in Table 31 for each order after the first.7
The proportion of short-interval births was higher— 29.6 per cent—
in the‘group of second births than in that of any later order up to
tenth and later, for which it was 30.6 per cent. The fifth order had
the lowest proportion of short-interval births (21.3 per cent).
In spite of the relatively high proportion of short-interval births
among births second in order, this order had a lower infant mortality
rate than any other. It is not surprising, therefore, to find that,
when allowance was made for the slightly greater prevalence of short
intervals among the second births and among those of high orders,
the increasing trend of the mortality rate by order of birth was not
materially altered. (Table 32.)
T

able

3 1 .—

Interval since preceding birth, by order o f birth; live births in Baltimore
second and later in order
Live births second and later
in order—

Order of birth
Total

Following preceding
births at short
intervals 1
Number

Per cent

Total.............

7,929

2,072

26.1

Second....................
Third......................
Fourth...................
Fifth......................

2,409
1,481
1,127
818

712
387
256
174

29.6
26.1
22.7
21.3

Live births second and later
in order—
Order of birth
Total

Following preceding
births at short
intervals 1
Number

Sixth__________
Seventh..... ........
___
Eighth__________
Ninth.......... ........
Tenth and later___

631
440
337
239
447

139
118
83
66
137

Per cent
22.0
26.8
24.6
27.6
30.6

1 For definition of interval see p. 60.

Age o f mother and interval since preceding birth.

A much more marked interrelation was found between order of
birth and interval since preceding birth when age of mother was
taken into consideration than when age of mother was disregarded.
Of the second births to mothers under 20 years of age £5.3 per cent
occurred after short intervals, as compared with only 21.2 per cent
of those to mothers between 25 and 30; of the third births to mothers
under 20 years of age 88.5 per cent occurred after short intervals, as
compared with 38.7 per cent of those to mothers between 20 and 25
and with 22.7 per cent of those to mothers between 25 and 30. Even
among the births of relatively high orders marked differences in the
proportions of short-interval births were found when different ageof-mother groups were compared. Thus of sixth births the percent
age that followed the preceding births b y short intervals decreased
from 36.3 for those of mothers between 25 and' 30 to only 9.2 for
those pf mothers between 35 and 40. (See General Table 18, p. 194.)
When allowance was made for this interrelationship, as in Table 32,
the .excess mortality among the births of late orders was considerably
reduced. Nevertheless, there was still evident a markedly greater
mortality among births of later than among those of earlier orders.
I f!or explanation of classification of births according to interval since preceding birth see p. 60. Data
relating to interval since preceding birth were obtained only for the births in Baltimore. F or infants
born at short intervals the mortality was higher than average. See discussion in next section, pp. 60-67.

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52
T

CAUSAL FACTORS IN IN F A N T MORTALITY

3 2 . — Relative mortality, by order o f birth, when the influence o f interval since
'preceding birth and when the influences o f both interval since preceding birth and
age o f mother are eliminated; single live births in Baltimore second and later in
order 1

able

Ratio of actual to
expected deaths—

At aver
age rates
for same
interval
and
same
age-ofmother
group
(per
• cent)

At aver
Ratio of
age rates
actual
same
rate to At aver for
average age rates interval
and
(per
for same
same
cent)
interval
age-of(per
mother
cent)
group
(per
cent)

Ratio.of
actual
rate to At aver
average age rates
(per
for same
cent)
interval
(per
cent)

Order of birth

Second....... .............
Third......................
Fourth___________

100.0

88.5
88. 6
95.8

87.1
88.6
98. 2

88. 2
93.1
101.3

Order of birth

Fifth____ ____
Sixth_____________
Seventh__________
Eighth and later...

103.9
98.3
111. 1
143.0

101.5
96.5
111.3
145.0

108.6
99.7
102.8
123.9

1 For number of deaths upon which these ratios are based see General Table 28, p. —.

Prematurity.

A slightly larger proportion of first births than of births of any
later order were premature,8 according to Table 33. This high pro
portion of premature births is doubtless associated with the high
mortality among first babies from causes peculiar to early infancy.
Among the premature the mortality rate for first births was lower
than that for any later order. Among the full-term births, on the
other hand, the mortality rate, as Table 34 shows, was higher for
first than for second infants. Evidently, therefore, the slightly
higher mortality found among first as compared with second births
can not be explained by the fact that the former group included a
larger proportion of premature births. (Compare also General Table
27, p. 197.)
^
The higher proportion of premature in the group of first births
tended, however, to neutralize the effect upon the infant mortality
rates of later orders of a higher proportion of plural births in the
births of those orders.
T

able

3 3 .—

Proportion o f premature births, by order o f birth; live births in eight
cities
Live births

Order of birth

Live births

Premature

Order of birth

Total .
Number

F irs t...._________
Third________ _
Fourth____ ______

Premature
Total

Per cent

Number

22,967

1,158

5.0

Fifth.......................

1,767

6,230
4,954
3,328
2,481

457
246
135
93

7.3
5.0
4.1
3.7

Seventh_______ ..

921
677
470
876

32
31
25
40

Ninth____ _______
Tenth and later___

Per cent
3.1
• 3.5
4rfi,
5.3
4.6

8 Westergaard gives figures showing that the proportion of premature is greater among first births than
among births of later orders. See Die Lehre von der Mortalität und Morbilität (Second Edition), p. 337.

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FREQUENCY OF BIRTHS
T

able

3 4 .—

Relative mortality, by order o f birth, fo r full-term and fo r all births; live
births in eight cities
Infant mortality rates

Order of birth

All
births

Infant mortality rates

Full term
Order of birth

Ratio to
Infant
average
rate (per mortal
ity rates
cent)

Ratio to
average
rate (per
cent)

Total.............

100.0

88.4

100.0

First........................
Second__________
Third...............
Fourths....... .........

94.2
86.1
94.1
97.8

76.4
70.5
86.1
91.7

86 4
79.8
97.4
103.7

All
births

Full term

Ratio to Infant
Ratio to
average
average
rate (per mortal rate (per
ity rates
cent)
cent)
Fifth........................

Tenth and later___

106.8
110.3
123.0
122.2
132.0
163.2

101.0
121.5
109.9
123.6
156.7

114 3
115.2
137.4
124.3
139.8
177.3

Plural births.

The proportion of twins and triplets tended to increase slightly
with the number in order of birth. Plural births formed only 1.5
per cent of the first and 2 per cent of the second births, while of those
tenth and later in order they constituted 3.6 per cent. (Table 35.)
Since the mortality among plural births was unusually heavy, as will
be shown later, the slightly greater prevalence of twins and triplets
among infants of later orders accounts for a small part of the high
mortality in these orders. That it accounted for only a small part
of this high mortality is shown by the fact, appearing in Table. 36,
that, though the rates for single births were all slightly lower, t h i s
trend was substantially the same as that exhibited by the rates for
all infants. The elimination of the plural births made the rate for
tenth and later orders appear slightly less excessive than when all
infants were included.
T

able

3 5 .—

Proportion o f plural births, by order o f birth; live births in eight cities
Live births

Order of birth

Live births

Plural

Order of birth

Total

Plural
Total

Number

Per 1,000

Total

22,967

529

23.0

First—.......
S econd.....
Third_____
Fourth.......

6,230
4,954
3,328
2,481

95
99
95
60

15.2
20.0
28.5
24.2

9 6 5 1 5 ° — 2 5 t ------ 5

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Number Per 1,000
Fifth.................
Sixth_________
Seventh____. . .
Eighth_______
Ninth...............
Tenth and later

1,767
1,263
921
677
470
876

28.3
42.0
26.1
19.2
17.0
36.5

54
T

CAUSAL FACTORS IN IN FAN T MORTALITY

able

3 6 .—

Relative infant mortality rates, by order o f birth; single and all
live births in eight cities
Infant mortality rates
All births

Order of birth

Single births

Rate

Ratio
to av
erage Rate
rate
(per
cent)

111.2

100.0

105.3

100.0

F irs t..................... . 104.7
S econ d ___ ________ 95.7
T h ir d ...................... 104. 6
Fourth..................
108.8

94.2
86.1
94.1
97.8

100.7
90.8
100.5
102.4

95. 6
86. 2
95.4
97.2

Total______ >,

Infant mortality rates

Ratio
to av
erage
rate
(per
cent)

All births
Order of birth

Fifth.................
Sixth ______
Seventh________
E ig h th .,.___
N inth..........
Tenth and later___

Single births

Rate

Ratio
to av
erage Rate
rate
(per
cent)

118.8
122.7
138.8
135.9
146.8
181.5

106.8
110.3
123.0
122. 2
132.0
163.2

109.5
109.1
134.9
128.0
138.5
167.0-

Ratio
to av
erage
rate
(per
cent)
104.0
103.6
128.1
121.6
131. 5
158.6

Type o f feeding.

£®
variations in type of feeding were found between births
ot different orders. (See General Table 30, p. 198.) Thus of the
infants surviving at the beginning of the third month 21.5 per cent
of the first born were artificially fed— a percentage that exceeded
that of any other order up to the group tenth and later, for which the
percentage (30.5) was markedly high. The smallest proportion
artificially fed at this age was found among third births. Of the
infants surviving at the beginning of the sixth month the highest
percentage artificially fed (37.1) was found among those who were
tenth and later in order and the lowest (25.2) among the ninth in
order; the proportion for the first bom was midway between the
two extremes (31.7). The high proportion of first and of tenth and
i^ter infants who were artificially fed may be due in small part to
the slightly larger percentage of premature in the first and of twins
and. triplets in the tenth and. later orders? since in hoth. these groups
as will be shown later (pp. 75 and 80-81), the proportion artificially
led was high. These slight differences in the proportion of premature
and plural births, however, can scarcely account for the differences
hi prevalence of artificial feeding in these order-of-birth groups.
The greater prevalence of artificial feeding among first than among
second infants tended to produce a higher mortality among the
former, especially from gastric and intestinal diseases. But for the
first born the mortality rate from gastric and intestinal diseases was
m fact lower than for infants of any other order. The high proportion artificially fed in the group of first-bom infants tended,
therefore, to lessen and obscure the advantage which they had over
infants of later orders in tlie matter of liability to mortality from
these diseases. The disadvantage due to the difference in type of
feeding was not great, however; if the same proportion of first-born
as of second-born infants had been artificially fed, at the average
difference m mortality between breast fed and artificially fed the
rate from all causes for the first born would have been reduced from
104.6 to 101.8. But this figure is still considerably above the rate
from all causes (95.7) for second births.
The greater prevalence of artificial feeding among infants tenth
and later in order than among those of earlier orders (third to fifth,

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FREQUENCY OF BIRTHS

for example) tends to explain in part the greater mortality among
the former. If the same proportion of the infants of the tenth and
later orders had been artificially fed as of those of the third, fourth,
and fifth, the rate of mortality for the former group would have been
reduced from 181.5 to 165.6, a very considerable reduction.
. The greater prevalence of artificial feeding among the first born
and among infants of the tenth and later orders appeared to have
been independent of the influence of age of mother, as Table 37 shows.
The numbers artificially fed among first-born infants and among
infants tenth and later in order of birth were much greater than the
numbers expected on the basis of the proportions artificially fed
among births to mothers of corresponding ages.
T a b l e 37.— Influence o f order o f birth upon the proportion o f infants artificially

fed, during the third month o f life, when influence o f age o f mother is eliminated'
infants in eight cities
.
Infants surviving at beginning
of third month
Order of birth

Actual
number
arti
ficially
fed

Expected Ratio of
number actual to
arti
expected
ficially
(per
fe d 1
cent)

Infants surviving at beginning
of third month
Order of birth

Actual
number
arti
ficially
fed

Expected Ratio of
number actual to
arti
expected
ficially
(per
fed 1
cent)

Total_______

4,431

4,430.9

100.0

Fifth..................

325

First........................
Second_________
Third_______
Fourth__________

1,259
948
580
444

1,161. 0
' 933. 3
628.8
477.3

108.4
101. 6
92. 2
93.0

345.8
254. 0

94.0
92.1

Tenth and later___

244

196.4

124.2

1Expected at average proportions artificially fed in each age-of-mother group.

Color and nationality of mother.
A considerably larger percentage of the births of orders for which
the infant mortality rates were above average than of those of
orders with low rates occurred to mothers belonging to race or
nationality groups for which the infant mortality rates were above
average. Table 38 shows, for example, that of the infants tenth
and later in order 48.3 per cent, as compared with 25 per cent of
the first born, were born to mothers of race or nationality groups
which had high rates.
When allowance was made in Table 39 for this disproportionate
weighting of the groups of infants of late orders with infants of
nationality groups for which the mortality rates were high, the
excess mortality associated with the high orders appeared* to be
somewhat diminished but was by no means eliminated. The
characteristic upward trend of the rates with the advance in order
of birth was still strikingly in evidence.

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56
T

CAUSAL FACTORS IN IN F A N T MORTALITY

able

3 8 .—

Proportion o f births to mothers o f nationalities with high infant
mortality rates, by order o f birth; live births in eight cities
Live births

Live births-

To
mothers of
nationalities
with high in
fant
mortality
rates1

Order of birth
Total

Number

Per cent

Total........... -

22,967

7,428

32.3

F irs t......................
Second___________
Third................. .
Fourth....... .............

6,230
4,964
3,328
2,481

1,657
1,393
1,091
'908

25.0
28.1
32. 8
36.6

To
mothers of
nationalities
with high in
fant
mortality
rates1

Order of birth
Total

Number Per cent
Fifth........................

1,767

688

38.9

Ninth_________ _
Tenth and later___

921
677
470
876

381
299
199
423

41.4
44. 2
42.3
48.3

1 Includes French-Canadian, Polish, Portuguese, “ other foreign born,’ ’ and colored. For basic figures see
General Table 31, p. 198.
T

able

3 9 .—

Relative mortality, by order o f birth, when influence o f color and nation
ality o f mother is eliminated; live births in eight cities
Infant deaths

Order of birth
Actual

Infant deaths

Ratio of
Ex
actual to
pected 1 expected
(per cent)

Total_______

2,555

2,555.0

100.0

First........................
Second....... .............
T hird.....................
Fourth....................

652
474
348
270

665.3
536.7
369.0
283.2

98.0
88.3
94.3
95.3

Order of birth
Actual

Ratio of
Ex
actual to
pected 1 expected
(per cent)

Fifth............... ........

210

203.0

103.4

Eighth................
N inth...
Tenth and later___

126
92
69
159

107.4
80.3
55.4
109.6

117.3
114.6
124.6
145.1

1 Expected at average rates for infants in each color and nationality group, irrespective of order of birth.

Earnings o f father.

A much larger proportion of the births of later orders than of the
first or second births occurred in families in which the fathers’
earnings were low. Table 40 shows that nearly two-fifths of the
tenth and later as compared with little more than one-fifth of the
first births occurred in families in which the fathers earned, less than
$550; and twice as large a proportion of the first and second as of the
tenth and later births occurred in families in which the fathers earned
$1,250 or over. Since low father’s earnings, as will be shown later,
were associated with high infant mortality rates, the correlation
between late order of birth and low father’s earnings might have
accounted for part or all of the high infant mortality rates associated
with late order of birth.
When the influence of this correlation between earnings of father
and order of birth was eliminated in Table 41, however, the effect
of order of birth appeared to be slightly diminished but b y no means
eliminated. In other words, after account was taken of the influence
of father’s earnings the mortality rates for the different orders of
birth showed the same trend, though the increase in the rates for
the later births was somewhat less marked.

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FREQUENCY OF BIRTHS
T

able

o f father, by order o f birth; live births in seven cities

4 0 . - ^ a m '^ s

Live births
Earnings of father
Order of birth
Total

Under $550

$1,250 and over

Number Per cent Number Per cent
Total.

21,536

F irs t.............
Second_______
Third____
Fourth___
Fifth......
Sixth__
Seventh_____
Eighth_____
Ninth . . .
Tenth and later

...................... ...........

5,910

27.4

1,296

21.9
24.7
26.9
30.5
32.0
32.3
36.5
35.4
36.8
39.9

2,302
847
820

327

2,252

10.5

1 For basic figures see General Table 32, p. 199.
T

able

41.

Relative mortality, by order o f birth, when influence o f earnings o f father
is eliminated; live births in seven cities
Infant deaths

Order of birth ,
Actual

T o ta l...........
First................
Second.............
T hird..........
Fourth___

Infant deaths

Ratio of
Ex
actual to
pected 1 expected
(per cent)

2,368

2,368. 0

617
440
315
252

624.4
500.8
339.8
258.6

Order of birth
Actual

100.0. Fifth...................
Sixth__________
98.8 Seventh.........___
87.9 Eighth________
92. 7 Ninth_________
97.4 Tenth and later.

Ratio of
Ex
actual to
pected 1 expected
(per cent)
186.5
134. 7
99. 0
73. 0
52. 6
98. 5

104.0
104.7
114.1
112.3
125.4
150.3

on *>eelea
■ group
average
,es order
°* mortality
prevailed among
amnnv tne
thp hirth«
nf
the same
earmngs
for ra*
each
of birth.in each earnings group
v had prevailed
births of

,
comparison, it must be conceded, does not give full weight
to the ejects of economic factors in producing greater mortality
ammig the births of late orders, for a large number of previous
births is usually associated with a large family, and the same earn
ings will not go so far with a large as with a small family. A corre
lation with income per unit of family would give a more satisfactory
basis for determining the influence of economic factors over the
ml ant mortahty rates for the different orders of birth.
Per capita earnings.

The marked relation which existed between later orders and low
per capita earnings 9 is shown in Table 42. Of the tenth and later
births, over seven times as large a proportion as of first births—
• '5 iPei
as C0IW ed with 12 per cent— occurred in families
than $20(3 6 ^er caP1^a mcoj:ne from the father’s earnings was less
®Per capita income from father’s earnings only. See discussion, pp. 149-150.

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58
T

CAUSAL FACTORS IN IN F A N T MORTALITY

able

4 2 . — Proportion of births in fam ilies with per capita income from father’ s
earnings of less than $200, by order o f birth; live births in seven cities

Live births-

Order of birth
Total

Total

Fourth..........

_____

In families with per
capita income of
less than $200 1

Order of birth
Total

In families with per
capita income of
less than $2001
Number

Number

Per cent

21, 536

10,388

48.2

Fifth...................... -

5,908
4,681
3,115
2,302

707
1,558
1,676
1, 689

12.0
33.3
53.8
73.4

Seventh.................
Eighth___________
Ninth____________
Tenth and later___

1,632
1,172
847
622
437
820

. 1,323
989
759
551
394
742

Per cent
81.1
84.4
89.6
88.6
90.2
90.5

i Income from earnings of father only. For explanation of classification see pp. 148-149. The father’s
earnings group $1,250 and over was not included in the classification by per capita income. For basic
figures see General Tables 32 and 33, p. 199.

In Table 43 a partial allowance was made for the association be
tween late orders and low per capita income from father’s earnings
which was found to characterize large families. The correction was
a somewhat crude one, since, for want of detailed data on age and
sex, the income from father’s earnings was considered to have been
distributed equally among all members of the family irrespective
of their relative requirements. This procedure introduced, in effect,
a classification according to the number of persons in the family—
a classification which paralleled that b y order of birth more closely
than was desirable in an analysis designed to distinguish the in
fluence of order of birth from that of economic need as measured by
family requirements.
In view of this difficulty it was surprising to find that the char
acteristic variations in the infant death rates b y order of birth
remained. The mortality among the first born appeared much
larger relatively to that among later infants than when no allowance
was made for the greater requirements of the larger families; and
that among second, third, and fourth babies appeared much lower
relatively to that among the first born and also to that among fifth and
later infants. On the other hand, the rates for infants of late orders
were not markedly above the average until the groups ninth and
tenth and later were reached. Among fifth and later infants the
mortality was considerably higher than that prevailing among those
who were second to fourth in order.
The correlation between late orders and large families seemed,
therefore, to account for a considerable part of the excess mortality
found among births of late orders, although a more careful measure
ment of economic need than the present tabulations permit would be
required to prove this conclusion.

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FREQUENCY OF BIRTHS

T a b l e 43 .— Infant mortality rates, by order o f birth, when influence of differences

in per capita income from father’ s earnings is eliminated; live births in seven
cities
Infant deaths
Order of birth
Actual

Infant deaths

Expect
ed 1

Ratio of
actual to
expected
(per cent)

Order of birth
Actual

....... .

2,368

2,367.8

100.0

Fifth.......... ............

First........................
Second............. ......
Third......................
Fourth..... ..............

617
440
315
252

555.3
477. 7
343.3
270.9

111. 1
92.1
91.8
93.0

Tenth and later___

Total

194
141
' 113
82
66
148

Expect
ed 1

Ratio of
actual to
expected
(per cent)

200.3
146.7
110. 5
82.8
61.3
119.0

96.8
96.1
102.3
99.0
107.7
124.4

1 Expected at average rates for the per capita income group for infants of fathers earning less than $1,250;
and for other infants at average rates for their groups—that is, earnings of $1,250 and over, no earnings, and
earnings not reported. See discussion, p. 148.

Summary.

The analysis by cause of death shows that the first births were
handicapped, as compared with those of later orders, b y a high
mortality from causes peculiar to early infancy. This mortality was
associated with a large proportion of premature births, but the dis
proportionate number of such births was not alone sufficient to
account for the high rate found for the first born. Some physical
handicap seems, therefore, to have affected first infants.
Once the first born had survived for a few weeks, however, they
had death rates that were lower than those of any later order. In
particular the mortality from gastric and intestinal diseases and from
respiratory diseases was lower among first infants than among those
of any other order. These low rates existed in spite of a slightly
greater prevalence of artificial feeding among first as compared with
second infants.
Leaving the first born out of account, the infant mortality rates
from all causes and from each of the principal causes showed a tend
ency to increase with the order of birth. Analysis shows that inter
correlations with other factors explain part, but not all, of this tend
ency. When allowances were made for age of mother and for
interval since preceding birth the excess mortality among the infants
of late orders, as compared with second or third babies, appeared
slightly less marked.
The greater prevalence of artificial feeding among tenth and later
infants accounted in part for their excess mortality. Although the
age of the mother was also a factor, this tendency toward artificial
feeding appeared to be associated, through an increasing inability
of the mothers to give their babies breast feeding, with the advancing
order of birth.
When allowance was made for the correlation between order of
birth and birth in nationality groups which had high rates of mor
tality, the tendency toward a rise in the rates as the order of birth
advanced was still apparent though slightly less marked than when
no such allowance was made.

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CAUSAL FACTORS IN IN F A N T MORTALITY

The correction for the correlation between late orders of birth
and low father’s earnings likewise lessened slightly the tendency
toward a rise in the rates as the order advanced. When further
allowance was made for the varying sizes of the families for the re
quirements of which the earnings had to be used, the excess mortality
among the later infants as compared with the average for all orders
seemed largely to disappear; but there still remained a markedly
more favorable rate for the second, third, and fourth babies than for
the first born and those fifth and later in order. ^ The mortality
among the babies of late orders still remained higher than that
among the second, third, and fourth infants.
A final conclusion is somewhat difficult to draw, since the data
available are too limited to justify an analysis b y all factors together.
To some extent, moreover, these different factors overlap, lh e
analysis b y age of motliGr and. interval since preceding birth, for
example, takes care of the economic factors so far as they produced
their effects through a greater birth frequency. As will be shown
later, certain of the marked differences in rates between the infants
of the various nationality groups were a reflection of differences m
earnings and appear to have been to a relatively slight degree due to
differences in racial vitality or in customs and traditions. The con
clusion may therefore be ventured that even if full allowance were
made for all the correlated elements a markedly greater mortality
would be found among births of later than among those of earlier
orders.
INTERVAL SINCE PRECEDING BIRTH

For all except first infants the length of time that has elapsed since
the next preceding birth may influence the chances of life. In the
present study this interval was measured in approximate terms only
b y the difference in even years between the mother’s age at the tune
of birth of the scheduled child and her age at the time of the pre
ceding birth.10
. p
,
The analysis given in Table 44 shows that the infants who were
born after the shortest intervals— i. e., after changes of only one year
in their mothers’ ages 10— since next preceding births to their mothers
had the highest mortality rate (146.7) and those who were born after
changes of four or more years had the lowest (84.9). The most
marked difference appeared between the rates for infants who were
born after changes of one year and after changes of two years, which
were 146.7 and 98.6, respectively. Practically no difference was
found between the mortality of infants born after changes of three
and of four or more years, the rates for these groups being 86.5 and
84.9, respectively.
10The only information obtained in regard to interval was the mothers’ ages expressed in even years at
successive births. The interval groups into which the data were analyzed were those in which the change
in them<rthOT’s age was one year(including a few cases in winch the mother’s age did not change) two
years, ^three years? and four or more yeare-groups for which the average intervals smra the preceding
births were slightly over one year, approximately two years and three years, and more than four years.
The data relating to interval are limited to one city, Baltimore.

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FREQUENCY OF BIRTHS
T

able

4 4 .—

Infant mortality rates, by cause o f death and interval since preceding
birth; 1 live births in Baltimore
Infant deaths from specified causes

Interval since preceding
birth1

Live
births

Gastric and
intestinal
diseases

Respira
tory
diseases

Early
Other causes
infancy
Infant
mor
Total tality
Infant
Infant
Infant
rates2 Num Infant
mor Num mor Num mor
mor
tality
tality
ber
tality
ber tality Num
rates2 ber rates 2
rates 2 ber rates 2

Total_____________

10,797

1,117

103.6

314

29.1

213

19.7

407

37.7

183

16.9

First births....... ...............
Second and later births...

2,868
7,929

272
845

94.8
106.6

67
247

23.4
31.2

42
171

14.6
21.6

111
296

38.7
37.3

52
131

18.1
16.5

Interval 1 year...........
Interval 2 years_____
Interval 3 years..........
Interval 4 years and
over............ ............
Interval not reported.

2,072
2,960
1,364

304
291
118

146.7
98.6
86.5

106
90
25

51.2
30.5
18.3

57
58
28

27.5
19.7
20.5

96
103
42

46.3
34.9
30.8

45
40
23

21.7
13.6
16.9

1,496
47

127
5

84.9

25
1

16.7

18.7

52
3

34.8

22
1

14.7

1 For definition of interval see p. 60.
s Not shown where base is less than 100.

Causes o f death.

Table 44 also shows that the trend of the rates from each of the
three principal groups of causes— those peculiar to early infancy,
gastric and intestinal diseases, and respiratory diseases— was similar
to that of the rates from all causes; in each case the infants whose
births occurred after short intervals (one year’s change in mother’s
age) had a markedly higher rate than those born after longer intervals.
For the one-year group, the mortality rate from causes peculiar to
early infancy was 46.3, as compared with 34.9 for the two-year group
and with 30.8 and 34.8 for the three and the four or more year groups,
respectively. The mortality from gastric and intestinal diseases
among the infants born after short intervals was 51.2, as compared
with 30.5 for those whose births followed intervals which averaged
about two years and with only 16.7 for those born after intervals
which averaged four years or more. From respiratory diseases the
rate for infants born after changes of only one year in their mother’s
ages since preceding births was 27.5, which was higher than the
rates for infants born after changes of two, three, and four or more
years— 19.7, 20.5, and 18.7, respectively. The mortality rate from
all other causes was decidedly higher for the short-interval infants
(21.7) than for other infants.
Neonatal mortality.

Furthermore, a markedly higher rate of mortality during the first
m onth11 was found among the short-interval group than among
infants born after intervals averaging about two, three, or four years
or more— 51.2, as compared with 37.3, 36.7, and 38.1, respectively.
(Table 45.)
11 For rates in later months see General Table 34. p. 199.

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CAUSAL FACTORS IN IN F A N T MORTALITY

Age o f mother and order o f birth.

A markedly smaller proportion of the infants born after short
intervals since preceding births than of those born after longer inter
vals, according to Table 46, were born to mothers under 20 years
and mothers 35 years of age and over— that is, belonged to age-ofmother groups with higher than average infant mortality rates.
Evidently, therefore, the effect of this disproportionate weighting of
the longer-interval groups with births in age-of-mother groups which
had high rates tended to raise the mortality among the longer-interval
groups, as compared with that among the short-interval groups, and
thus to counteract in part the influence of short intervals in causing
a high death rate.
T

able

4 5 .—

Neonatal mortality rates, by interval since 'preceding birth;1 livebirthsin
Baltimore

Interval since preceding birth i

Total..............................
First births________________
Second and later births_____
Interval 1 year............................
Interval 2 years.................... ...... ........
Interval 3 years_____________ _
Interval 4 years and over............
Interval not reported....... .......

Live
births

Deaths Neonatal
mor
under 1
tality
month
rates 3

10,797

477

44.2

2,868
7,929

150
327

52.3
41.2

2,072
2,930
1,364
1,496
47

106
110
50
57
4

51.2
37.3
36.7
38.1

1 For definition of interval see p. 60.
1Not shown where base is less than 100.
T

4 6 . — Proportion o f births to mothers under 20 and to those 35 years o f age
and over, by interval since preceding birth; 1 single live births in Baltimore

able

Single live births—

Interval since preceding birth 1
Total

To mothers under
20 and those 35
years of age and
over
Number Per cent3

Total.............................. ......
First births_________________
Second and later births.........
Interval 1 year_______ ____
Interval 2 years.. .............
Interval 3 years.........................
Interval 4 years and over....... ..............
Interval not reported_____
1 For definition of interval see p. 60.
* Not shown where base is less than 100.

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10, 537

2,503

23.8

2,830
7,707

762
1,741

26.9
22.6

2,026
2,867
Í, 316
1,451
47

374
570
315
467
15

18.5
19.9
23.9
32.2

FREQUENCY OF BIRTHS

T a b l e 47 .— Proportion o f births of orders seventh and later in order, by interval

since preceding birth; 1 single live births in Baltimore second and later in order
Single live births second and
later in order—
Interval since preceding birth1
Total

Total______________________________: __________________________
One year......................................................... ..............................................
Two years................................................. ........... ........................................
Three y e a r s______ ____ ___ ______ ____ _____ _____________ _____ ____
Four years and over.................................................. ...................................
Not reported............ ...... ..................... ..........................................................

Of orders seventh
and later
Number

Per cent2

7,707

1,414

18.3

2,026
2,867
1,316
1,451
47

389
544
253
207
21

19.2
19.0
19.2
14 3

1 For definition of interval see p. 60. '
8 N ot shown where base is less than 100.

So far as the correlation between interval and order of birth is
concerned, Table 47 shows that except for the infants who were born
after the longest intervals the percentages of infants of orders seventh
and later were practically the same for each interval group. So far,
therefore, as any correlation with age of mother on the one hand and
order of birth on the other is concerned, neither of these factors
could have changed the trend of the mortality rates b y interval. The
high mortality found among infants born after short intervals since
preceding births is not to be ascribed, in other words, either to the
influence of order of birth or to that of mother’s age.
Prematurity.

A considerably larger proportion (6.4 per cent) of the short-interval
births than of any other group were premature. The smallest
roportion of premature births— 3.6 per cent— was found among
irths which followed intervals of about two years; in the four or
more year group the proportion of premature births was 4.6 per cent.
It is. interesting to note also in Table 48 that even in the shortinterval group the proportion of premature births was less than that
among first births. (See also General Table 35, p. 200.)

Plural births.

The differences in the proportions of twins and triplets in the
different interval groups, as shown in Table 49, were relatively
slight. The proportion was smallest for the short-interval births, 2.2
per cent of which were plural (even this figure was higher than that
for first births), and rose to 3.5 per cent for infants born after intervals
of three years.

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CAUSAL FACTORS IN IN F A N T MORTALITY

T a b l e 48 .— Proportion of premature births, by interval since preceding birth;1

live births in Baltimore
Live births
Interval since preceding birth *

Premature births
Total
Number Per centJ

Interval not reported - ....... ................ ......................._.............................
i For definition of interval see p. 60.

10,797

591

5.5

2,868
7,929

230
361

8.0
4.6

2,072
2,950
1,364
1,496
47

132
105
50
69
5

6.4
3.6
3.7
4.6

1 Not shown where base is less than 100.

T a b l e 49 .— Proportion o f plural births, by interval since preceding birth; 1 live

births in Baltimore
Live births
Interval since preceding birth 1

Plural births
Total

Total________________ _______________ _________________________
Second and later births____ ____ ____ ___________________________
Interval 1 year........ __..............................................................................
Interval 3 years________ _______ _______________________ ____ _____
Interval not reported................................. ................ __.s....................

Number

Per cent

10,797

260

2.4

2,868
7,929

38
222

1.3
2.8

2,072
2,950
1,364
1,496
47

46
83
48
45

2.2
2.8
3.5
3.0

1 For definition of interval see p. 60.

Type o f feeding.

•

A markedly larger proportion of infants who were bom after
changes of only one year m their mothers’ ages since the next pre
ceding birth were artificially fed than of infants born after longer
intervals. Of infants surviving at the beginning of the third month
24.1 per cent of the one-year as compared with 15.5 per cent of the
two-year group were artificially fed. (See General Table 36, p. 200.)
This difference in the prevalence of artificial feeding was manifest
throughout the first nine months of life, the percentage artificially
fed being nearly 10 points higher in the third, sixth, and ninth
months, for example, for the infants born after short intervals than
for those whose birth followed intervals averaging about two years.
The greater prevalence of artificial feeding among infants born
at short intervals after preceding births can account only in part,
however, for their markedly heavy mortality rate; if the same per
centage of these infants as of those born at intervals averaging about
two years had been artificially fed, then the reduction in mortality
due to the difference in the rates between artificially-fed and breast
fed infants would have been only from 146.7 to 133.2.

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FREQUENCY OF BIRTHS

Color and nationality o f mother.

A somewhat larger proportion of short-interval than of other births
were to colored mothers or mothers of nationalities having infant mor
tality rates higher than average, according to figures shown in Table
50. This higher proportion, however, as shown in Table 51, accounts
for only a small part of the excess mortality among infants of the
short-interval group. When the influence of nationality was elimi
nated, the comparison of the rates for the one-year and the four year
or more groups became the ratio 132 to 84.8 instead of the ratio 137.6
to 79.6. In other words, after allowance was made for the influence
of nationality the relative mortality among the infants of shortinterval birth was only 1.6 times that among infants born after inter
vals of four or more years, as compared with 1.7 times when no such
allowance was made. The effect of differences in the proportions of
the different nationalities in the several interval groups was evidently
slight.
T a b l e 5 0 . — Proportion o f births to mothers o f nationalities with high infant mortality

rates, by interval since preceding birth; 1 live births in Baltimore second and later
in order
Live births second and later
in order—
T o mothers of na
tionalities with
high infant mor
tality rates 2

Interval since pre
ceding birth i
Total

Number

Live births second and later
in order—
To mothers of na
tionalities with
high infant mor
tality rates2

Interval since pre
ceding birth i
Total

Per cent

Total.............

7,929

1,912

24.1

One year_________
Two years________

2,072
2,950

594
757

28.7
25.7

Number Per cent
Three years...........
Four years and over.
Not reported.........

1,364
1,496
47

293
254
14

21.5
17.0
29.8

1 For definition of interval see p. 60.
2 Includes Polish, “ other foreign born,” and colored. For basic figures see General Table 37, p. 200.
T

5 1 . — Relative mortality, by interval since preceding birth,1 when influence o f
nationality is eliminated; live births in Baltimore second and later in order

able

Infant deaths
Interval since pre
ceding birth i
Actual

One year____ _____
Two years..............

Infant deaths

Ratio of
to
Expected2 actual
expected
(per cent)

845

845.1

100.0

304
291

230. 3
317. 5

132. 0
91.7

Interval since pre
ceding birth i
Actual

Four years and over.
Not reported...........

118
127
5

Ratio of
to
Expected2 actual
expected
(per cent)
142. 5
149.7
5.1

82.8
84.8

1 For definition of interval see p. 60.
2 Expected if the average mortality rate for births second and later in order for each nationality had
prevailed irrespective of interval since preceding birth.

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CAUSAL FACTORS IN IN FA N T MORTALITY

Earnings o f father.

The correlation between father’s earnings and the prevalence of
short-interval births is shown in Table 52. The differences in the
proportions of births by intervals in families in which the fathers
earned less than $650—families in which infant mortality was,above
average— were not great, the percentages for births in the one, two,
and three year groups being 48.7, 47.2, and 45.8, respectively. For
the four or more year group, however, the percentage dropped to
36.8. If allowance were made, therefore, for the smaller proportion
of infants born in families with low earnings, among the infants born
after the longest intervals, the infant mortality rate for these infants
would be slightly raised. As was the case with the allowance for
differences in nationality, however, such an allowance for differences
in economic status is shown in Table 53 to have relatively little effect
upon the high mortality among the infants born after short in
tervals.12
T a b l e 52 .— Proportion o f births in fam ilies in which the father earned less than

$650, by interval since preceding birth; 1 live births in Baltimore 2
Live births—

Interval since preceding birth1
Total

In families in which
father earned less
than $650
Number Per cent*

10,797

4,689

43.4

2,868
7,929

1,088
3,601

37.9
45.4

2,072
2,950
1,364
1,496
47

1,010
1,393
625
551
22

48.7
47.2
45.8
36.8

1 For definition of interval see p. 60.
2 For basic figures see General Table 38, p. 201.
s Not shown where base is less than 100.
T a b l e 53 .— Relative mortality, by interval since preceding birth, ° when influence

of earnings o f father is eliminated; live births in Baltimore second and later in
order
Infant deaths

Infant deaths

Interval since pre
ceding birth °

Two years_________

Ratio
Ratio of origi
of nal rate
Ex actual to aver
Actual pect to ex age (per
ed * pected cent) «
(per
cent)'
845

845.0

100.0

304
291

226. 5
317.8

134. 2
91.6

137.6
92.5

Interval since pre
ceding birth <*■

Three years________
Four years and over.
Not reported.. ____

° For definition of interval see p. 60.

Ratio
of
Ex actual
Actual pect to ex
ed * pected
(per
cent)'
118
127
5

146.1
149.5
5.1

80.8
84.9

6 Expected at average rates in each earnings group, irrespective of interval since preceding birth.
« Not shown where base is less than 100.

12 For correlation with per capita earnings see General Table 39, p. 201.

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Ratio
of
origi
nal
rate to
aver
age
(per
cent) ®

81.1
79.6

FREQUENCY OF BIRTHS

Summary.

The infants born after short intervals had a markedly high rate of
mortality from all causes, from causes peculiar to early infancy, from
respiratory diseases, and from gastric and intestinal diseases.
Though certain other factors— premature birth, plural birth, order of
birth, and age of mother— were to a slight degree correlated with
short-interval birth, these factors do not account for this excess
mortality. When allowance was made for the slightly greater preva
lence in the short-interval group of infants of nationalities with high
mortality rates and of infants born in families in which the father’s
earnings were low, the relative mortality of the group appeared to be
only very slightly reduced. The greater prevalence of artificial
feeding in the short-interval group accounts in part, but by no means
entirely, for its relatively high death rate. Apart from all these
factors the short-interval infants had a markedly higher mortality
than other infants. Evidently some factor that is intimately con
nected with the short interval— perhaps through the influence of
frequent births upon the mothers health— affected adversely the
chances of life of the infants who followed closely after preceding
births.
INTERVAL BEFORE SUCCEEDING PREGNANCY

An interval of less than one year between the birth of one child
and the commencement of a succeeding pregnancy may exert an
influence upon the earlier child’s chances of reaching his first birthday,
especially if the commencement of the succeeding pregnancy is fol
lowed by early weaning.
According to Table 54, in 11.4 per cent of the total number of cases
of five births the mother became pregnant during the infant’s life
and before he had passed his first birthday. The proportion of
months lived, however, b y infants after their mothers had become
pregnant was much smaller, only 4.7 per cent. The possible contri
bution of this factor to the general infant mortality rate was therefore
comparatively slight. Data on interval between birth of infant
and succeeding pregnancy were obtained only for the births in
Baltimore.

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68
T

CAUSAL FACTORS IN IN F A N T MORTALITY

5 4 . — Proportion o f births to mothers who became pregnant during first year of
infant’s life, and o f months lived by infants between beginning o f the subsequent
pregnancy and end o f their first year; infants in Baltimore

able

Months
lived1

Live births
Condition of mother during first year of infant’s life

Per cent Per cent
Number distribu distribu
tion
tion
10,797

100.0

21,232
29, 565

11.4
88.6

4.7
95.3

1 The total number of months lived by all these infants from birth to the end of the first year was 120,161;
of these, 5,706.5, or 4.7 per cent, were lived b y infants after their mothers had become pregnant, and
114,454.5, or 95.3 per cent, were lived b y infants whose mothers did not become pregnant during their first
year and b y infants before their mothers became pregnant.
2 Sixty oases in which the mother became pregnant and the infant survived the year but for which the
month when the mother became pregnant was not known are included in column 1, but the months lived
after the mother became pregnant could not be included in column 3. For months in which the mother
became pregnant see General Table 40, p. 201.
^
2 Including 300 infants who died before their mothers became pregnant but whose mothers became preg
nant within one year after infants’ birth; 5 cases for which it was not reported whether the mother became
pregnant before or after the infant died; and 28 cases in which the mother became pregnant in the same
month in which the infant died.

During the 5,706.5 months lived by infants after their mothers
became pregnant and before they reached their first birthday 75
deaths occurred, giving an average monthly death rate of 13.1.
Since these were largely months of the latter part of the infants’
first year of life, this average monthly rate was evidently considerably
higher than that for other infants of the same age. If the average
mortality prevailing in each month had prevailed among these infants
the deaths among them would have numbered only 27, or a little over
one-third as many, as Table 55 shows. Even though the numbers
are small, this difference indicates clearly that an unusual hazard
to the infant was associated with the mother’s closely succeeding
pregnancy.
T

5 5 . — Relative mortality among infants o f mothers who became pregnant during
first year o f infant’s life, when effect o f difference in infant’s age and type o f feeding
is eliminated; infants in Baltimore

able

Infants of mothers becoming
pregnant during first year
of infant’s life
Expected deaths

Type of feeding
Actual
deaths

T o t a lBreast.......... .
Partly breast.
Artificial____

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On basis On basis
of
of
average feeding
mortality reported
27.0

48.3
1.0
1.5
45.8

FREQUENCY OF BIRTHS

Type o f feeding.

A partial explanation of this excess mortality among the infants
of mothers who became pregnant is found in the greater prevalence
among them of artificial feeding. Of the months lived from the
beginning of a subsequent pregnancy to the end of the ninth month
of life by infants whose mothers became pregnant before that time,
78.7 per cent were months of artificial feeding, as compared with
23.3 per cent of all months lived to the end of the ninth by all infants.
(See General Table 42, p. 202.) This greater prevalence of artificial
feeding was due in part, it is true, to the fact that the months lived
after the beginning of a succeeding pregnancy were largely months
of late infancy during which artificial feeding was much more common
than during earlier periods of life. But it was not b y any means
due wholly to this fact, for these infants were artificially fed in
markedly larger proportions than other infants of the same ages.
Thus of the infants whose mothers had previously become pregnant
81.2 per cent of those surviving at the beginning of the fifth and 81.9
per cent of those surviving at the beginning of the ninth month were
artificially fed, as compared with 25.7 per cent and 31.9 per cent
artificially fed, respectively, among all infants surviving at the begin
ning of the same months. (See General Table 43, p. 202.) Evi
dently an important factor in the excessive mortality among the
infants whose mothers became pregnant during the first year of the
infants’ life, as Table 55 clearly shows, was the markedly greater
tendency among them toward artificial feeding. The excess mortality
among the artificially fed, as will be shown later in connection with
the discussion of type of feeding, was greater the earlier the arti
ficial feeding was commenced; among infants whose mothers became
pregnant after the ninth month, it is doubtful whether the greater
tendency toward artificial feeding produced any increase in the
death rates.
Color and nationality o f mother.

According to Table 56 a slightly larger proportion of the infants
whose mothers became pregnant during the first year of the infants’
life than of all other infants belonged to nationality groups having
high mortality rates— 31.7 per cent as compared with 24 per cent.
(See also Table 93, p. 113.) This tendency toward a slight over
weighting of the group with infants of nationalities having high
rates would account in part for the excess mortality among the
former.
Earnings o f father.

A slightly larger proportion of infants whose mothers became
pregnant during the infants’ first year of life than of all other infants,
according to figures given in Table 57, were born in families in which
the father earned less than $650— 51.8 per cent as compared with
42.4 per cent. (See also Table 140, p. 153.) The tendency to over
weight this group with infants in the income groups having high
mortality rates, like the overweighting of the group with infants of
■nationalities having high rates, also accounts in part for their excess
mortality.
96515°—25t——6

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70
T

CAUSAL FACTORS IN IN F A N T MORTALITY

5 6 . — Proportion o f births to mothers o f nationalities with high infant mor
tality rates, by pregnancy o f mother during first year o f infant’ s life; infants in
Baltimore

able

Live births—
T o mothers of na
tionalities with
high infant mor
tality rates1

Condition of mother during first year of infant’s life
Total

Number
Total............................................................................. .
Mother pregnant____________ ____________________
Mother hot pregnant............... ............... _

Per cent

10,797

2,685

24.9

1,232
9,565

390
2,295

31.7
24.0

1Includes Polish, “ other foreign born,” and colored.
T

5 7 . — Proportion o f infants born in fam ilies in which the father earned less
than $650, by pregnancy o f mother during first year o f infant’ s life; infants in
Baltimore

able

Live births—

Condition of mother during first year of infant’s life
Total

In families in which
father earned less
than $650
Number Per cent

Total____ _______ ________
Mother pregnant____ ______________ _
Mother hot pregnant. ................. „ ................

10,797

4,689

43.4

1,232
9,565

638
4,051

51.8
42.4

Summary.

The mortality among infants whose mothers became pregnant
during the infants’ first year of life was over two and one-half times
the average rate during corresponding months for all infants. This
excess mortality was largely accounted for by the greater prevalence
of artificial feeding but was due in part to the fact that the group
included an undue proportion of mfants of nationalities having
high mortality rates as well as an undue proportion of those born in
families with low incomes for which the infant mortality rates were
markedly above average.
GENERAL SUMMARY

The influence of “ birth frequency” is seen to have been of com
posite character, contributed to by four factors— age of mother,
order of birth, interval since preceding birth, and interval before suc
ceeding pregnancy.
Since the influence of “ birth frequency” is of composite character,.,
the relation between changes in the birth rate and the infant mortality
rate depends upon the relation between changes in the birth rate
and the separate factors into which it is analyzed. Thus a high
birth rate commonly signifies early marriages, many births of high

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* FREQUENCY OF BIRTHS

orders, and short intervals between births; it is also found associated
with low economic status. A low birth rate, on the other hand,
usually means late marriages, relatively few births of high orders,
and perhaps relatively longer intervals between births, and it is
commonly associated with relatively high economic status. In
order to test the true influence of a change of the birth rate upon
infant mortality, definite information should be available showing
to what degree the change in the rate is due to changes in the pro
portion of births to young mothers and to mothers 35 years of age
and over, the proportion of births of late orders, and the proportion
of short-interval births. Only with data on these points is it possible
to distinguish between the influence attributable to differences in
the birth rate per se and that due to differences in economic status
or economic need, with which the birth rate is closely associated.

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TYP E O F B IR TH

The points next to be considered are whether the birth occurred
prematurely or at full term, whether it was single or plural, and
whether the delivery was instrumental or normal. Other points of
interest, such as type of operative delivery, can not be treated in this
study because of the absence of the necessary data.
PREMATURITY

The infants reported to have been prematurely born numbered
1,158, constituting 5 per cent of the total number of live births.
The period of gestation given on the birth certificate— or, if it was
not given, then the period reported by the mother— was accepted; all
births were classified as premature for which the number of months’
gestation was stated as eight or less.
Of these prematurely born infants over half (626) died before the
end of the first year of life, and the mortality rate was 540.6. This
rate for the premature was over six times as high as that for the
infants who were born at term (88.1).
Causes o f death.

In Table 58 the rates of mortality from each of the principal groups
of causes of death are shown for premature and for full-term infants.
The excessive mortality among the premature appears to have been
due largely to causes peculiar to early infancy. The rate from this
group of causes was nearly 25 times as high among the premature as
among the full-term infants. Deaths from malformations, also,
were extremely prevalent among the prematurely born. From all
other causes together the mortality among the premature averaged
one and three-fourths times as high as that among the full-term
infants.
T

able

58.— Infant mortality rates, by cause o f death and term; live births in eight'citiesi
Full-term births
Cause of death

All causes____

___ ___

Gastric and intestinal diseases_____________________ _________
Respiratory diseases..... ................ ...... .....................' ..................
M alformations....... ..................... ......... ...................... .................
Early infancy............ ............................................................... .
Epidemic and other communicable diseases____________ _____
External causes.... ...................
..................... ...... ...................
Diseases ill defined and unknown___________________________
Other causes......... .........................................................................

Infant
Infant
Deaths mortality Deaths mortality
rates
rates
1,917

88.1

626

540.6

689
414
79
356
144
13
47
175

31. 7
19.0
3.6
16.4
6.6
.6
2.2
8.0

51
34
20
469
17
1
10
' 24

44. 0
29.4
17.3
405.0
14.7
.9
8.6
20.7

1 F or figures showing causes of death in detail see General Table 44, p. 203.

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Premature births

TYPE OF BIRTH

Neonatal mortality.

The neonatal mortality rate for premature infants was very high,
as would be expected from their high mortality from causes peculiar
to early infancy. Of the 1,158 premature infants 510 died within the
first month, and their neonatal mortality rate was 440.4 as compared,
with only 23.8 for the full-term infants. (See General Table 45,
p. 203.)
Plural births.

Of the premature births 10.5 per cent were plural, as compared
with only 1.9 per cent of the full-term births. Since twins and tnplets
had a very high mortality, this markedly larger proportion of plural
births in the group of premature than in that of full-term infants
increased decidedly the death rate of the prematurely bom . The
mortality rate among the premature infants was 6.14 times that
among the full-term infants, as Table 59 shows. But when the actual
deaths among the prematurely born were compared with the deaths
expected at the rates prevailing among the full-term single and fullterm plural infants, respectively, it appeared that the mortality
among the premature was only 5.13 times as high as that among the
full-term births. The correction for the greater proportion of plural
among the premature thus reduced the ratio between the mortality
rates b y one-sixth. .
For the single births alone the mortality among the premature
was 6.3 times that among the full-term births; but for the twins and
triplets, for whom tho fact of plural birth seems to have exerted a
markedly adverse influence, the mortality among the premature was
only a little over twice as high as that among the full-term births.
T a b l e 59 .— Relative mortality among premature and full-term infants fo r single and

plural births; live births in eight cities 1
Deaths of infants prematurely born

Single or plural birth
Actual

Total..........................................
Single_______
P lu ral.................

626
550
76

Expected at aver
age rates among
all full-term in
fants

Expected at aver
age rates among
full-term single
and plural in
fants

Number

R atioJ

Number

102.0

6.14

122.1

5.13

87.3
34.8

6.29
2.18

R atio 1

1 For basic figures see General Table 46, p. 204.

1 Ratio of actual to expected deaths.

Sex.

A slightly larger proportion of the premature than of the full-term
infants were of the male sex— 54.3 per cent as compared with 50:8 per
cent. (See General Table 4, p. 188.) Since the death rate among the
males was somewhat higher than that among the females, the slightly
greater preponderance of males among the premature would account
for a small part of the excess mortality associated'with prematurity.

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CAUSAL FACTORS IN IN FA N T MORTALITY

The influence of this factor, however, was not great, for when allow
ance was made for it in Table 60 and the actual deaths among the
male and female premature infants were compared with those ex
pected at the rates prevailing among the male and female full-term
infants, the relative mortality among the premature was reduced
from 6.14 only to 6.10 times that among the full-term births.
T

able

6 0 .—

Relative mortality among 'premature and full-term infants, by sex; live
births in eight cities
Deaths of infants prematurely born

Sex
Actual

626
359
267

Expected at aver
age rates among
full-term infants

Expected at aver
age rates among
full-term infants
of the same sex

Number

R atio1

Number

102.0

6.14

102.7

6.10

61.1
41.6

5.88
6.42

R atio1

1 Ratio of actual to expected deaths.

Death o f mother.

Of the premature births 2.4 per cent were to mothers who died
within one year after confinement, as compared with only 0.5 per
cent of the full-term births. (Compare General Tables 7 and 47,
pp. 189 and 204.) Since the infants born to mothers who died
within one year after confinement were characterized b y a very
heavy death rate during the first year of life (p. 33), the high mor
tality among the premature was due, in part, to the larger propor
tion among them of infants born to such mothers. This dispropor
tionate number of births to mothers who died was not, however,
a very important influence in the high mortality among the pre
mature as compared with that among the full-term infants, as
Table 61 shows. Though the death rate for the infants prematurely
born to mothers who died was three times that for the infants born
at term to such mothers, the rate for the other premature was over
six times that for the full-term infants.1 When these two ratios
were averaged the relative mortality among the premature appeared
to be 5.84 times that among the full-term infants, as compared
with 6.14 when no account was taken of the disproportionate num
ber of premature infants whose mothers died.
1 The limitations restricting the use of such ratios are well illustrated in this example, for, although the
mortality among the infants prematurely born to mothers who died within one year after confinement
was practically 1,000, it was only about three times that among the infants born at term to mothers of
this group. Nevertheless, though great weight should not be placed upon small variations between the
ratios, the comparison expresses the differences between the groups in an effective manner. In such cases
as these a better idea of the relative influence of prematurity can be gained b y a study of the ratios and
the mortality rates.

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TYPE OP BIRTH
T

able

6 1 .—

Relative mortality among premature and full-term infants, by death o f
mother; live births in eight cities
Deaths of infants prematurely born

Death of mother at or within one year after
confinement
Actual

Total____________________ ________

626

Mother died at or within one year after
confinement............................................._
Mother survived the year_________ ______

27
599

Expected at average
rates among all fullterm infants

Expected at average
rates among full-term
infants in specified
group

Number

102.0

Ratio1
6.14

Ratio1

107.3

5.84

8.7
98. 6

3.10
6.08

1 Ratio of actual to expected deaths.

Type o f feeding.

A markedly larger proportion of the premature than of the fullterm infants were artificially fed. Thus of the babies who lived to
be fed, 23 per cent of the premature, as compared with only 9.7 per
cent of those born at term, were given exclusively artificial feedmg
during the first month. In the ninth month the artificially fed con
stituted 51.5 per cent of the premature, as compared with 34.5 per
cent of the full-term infants. (See General Table 48, p. 205.) And
of the months up to the end of the ninth lived by babies who were
prematurely born 40.2 per cent were months of artificial feeding, as
compared with only 24.4 per cent of those lived by babies who were
born at term.2 Since such feeding was found to be associated with
a markedly high death rate, as will be shown later (p. 89), the mor
tality among the premature as compared with the full-term infants
might have been mcreased by the disproportionate number of arti
ficially fed among the former.
When allowance was made, as in Table 62, for variations in the
>revalence of breast and artificial feeding, a very great difference was
ound between the mortality among the premature and that among
the full-term infants during the first day or two of life before feeding
was commenced. In fact, the mortality during this period among the
premature was over 30 times that among the full-term babies.
Of the infants who lived to be fed the mortality among the prema
turely born averaged 4.3 times that among the babies born at term
who received the same type of feeding. O f those breast fed the mor
tality was nearly nine times as high among the premature as a m o n g
the full-term infants, while of the artificially fed the mortality among
the former was not quite three times as high as that among the latter.

J This tendency was found not only among the plural premature but also among the single premature.
Of the months up to the end of the ninth lived by the premature single infants 38.7 per cent were months ■
of artificial feeding, as compared with 24.1 per cent of those lived by full-term single infants. The corre
sponding percentages for the premature and full-term twins and triplets were 65 and 43.6. See General
Table 49, p. 206.

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CAUSAL FACTOES IN IN F A N T MORTALITY

T able 62 .-— Relative m ortality o f 'premature and fu ll-term in fan ts in eight cities, by
typ e o f feedin g
Infant deaths
Type of feeding
Actual

Expected

Ratio of
actual to
expected

626

76.51

8.2

340
283
131
23
129
3

10.89
65.62
14.85
5.34
45.43

31.2
4. 3
8.8
4,3
2,8

Other factors.

The correlations between the proportion of premature births and
factors other than those already discussed are of comparatively little
importance in explaining the relatively high mortality among the
premature infants. In other words, the high mortality among the
premature relatively to that among the full-term infants is not to be
explained to any extent b y undue proportions among them of births,
for example, of orders, or to mothers of ages, or following preceding
births b y intervals, for which the infant mortality rates were high.
Order o f birth.— Of the premature infants a slightly smaller pro
portion than of those born at term (19.6 per cent as compared with
26.4 per cent) were of orders fifth and later, for which the death rates
were above average. (See General Table 50, p. 206.) The high
mortality among the premature was not due, therefore, to any
unfavorable weighting of this group with births of orders character
ized by high rates. On the contrary, a correction for the dispro
portionate number of births of low orders among the premature would
tend to increase the ratio of the mortality among them to that of the
full-term infants.
_ •, _ ■
,.
,
Aqe o f mother.— On the other hand, a shghtly larger proportion of
the premature than of the full-term births (25.3 per cent as compared
with 22.6 per cent) were to mothers who either were under 20 or were
35 years of age or over; that is, belonged to age-of-mother groups for
which the death rates were above average. (See General Table 51,
p. 206.) The high mortality among the premature might have been
caused in part, therefore, by the somewhat disproportionate number
of such infants born to mothers of these age groups. But this
influence was the opposite of that shown for order of birth; and, since
the differences in the proportions were not great, it may be that the
two influences tended to cancel each other.
A
a
Interval since preceding birth.— Of the premature infants second and
later in order 18.8 per cent, as compared with 12.1 per cent of the lullterm infants of the same orders, were born at short intervals4 after the
next preceding births; i. e., belonged in the interval group for which
» 'Nevertheless order of birth, for example, may be an important causal factor in the occurrence of prematorebirths^apota^whiehis ofes^cial interest in the analysis of the reasons for the variation m mortality
amone infants of different orders. The influence of each of these other factors m the occurrence of premature
births8is discussed further later in this section (pp. 77 to 78) and also m connection with the analysis of
the influence of each of these factors upon the infant mortality rate*
4 For definition of “ short interval” see p. 60.

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T Y P E O F B IR T H

the mortality rate was above average. (See General Table 52, p. 206.
On the other hand 39.5 per cent of the premature, as compared with
only 26.5 per cent of the full-term infants, were first infants, among
whom the mortality rate was considerably below average.5 Evidently
these two influences, also, tended to offset each other.
Color and nationality o f mother, and economic factors.— A considera
bly smaller proportion of the premature than of the full-term births
(25.2 per cent as compared with 32.7 per cent) were to mothers of
nationalities for which the mortality rates were above the average.
(See General Table §3, p. 206.) Of the premature, furthermore, a
slightly smaller proportion than of the full-term infants (39.2 per
cent as compared with 42.6 per cent) were born in families in which
the fathers earned less than $650, a group for which the mortality
rate was above the average. (See General Table 54, p. 207.) These
differences seem to be of relatively minor importance; but if al
lowances were made for the slightly smaller proportions among the
prematurely born of infants who were handicapped either by the
nationality customs and traditions or by the comparatively low
economic status of their families, the relative mortality among the
premature as compared with that among the full-term births would
appear to be slightly increased. On the other hand, a slightly larger
proportion of the premature than of the full-term infants (16.1 per
cent as compared with 13.3 per cent) were born to mothers who were
gainfully employed away from home during pregnancy. (See General
Table 55, p. 207.) The effect of a correction for the slightly greater
prevalence of such employment among the mothers of premature
than among those of full-term infants would tend to offset the correc
tions for nationality of mother and earnings of father.
So far as explaining the high mortality among premature infants
is concerned, these correlations with social and economic factors are
of relatively little importance.
Causes o f prematurity.

Since the mortality among the premature was in all circumstances
very high as compared with that among the full-term infants, the
causes that produce or influence prematurity are of especial interest.
The preceding discussion has indicated several factors that appear
to have influenced the occurrence of premature births. The high
proportion of premature among twins and triplets suggests that
plural birth or some factor connected with it may have been re
sponsible in some cases for shortening the period of gestation. (See
Table 59, p. 73.) Sex seems also to have had an influence, for the
proportion of premature births among males was slightly greater
than that among females. (See Table 60, p. 74.) Furthermore,
prematurity was unusually prevalent among first babies, among the
infants of young mothers, and among infants who were born at short
intervals after preceding births. (See Table 33, p. 52; Table 19, p.
44; Table 48, p. 64; and General Table 35, p. 200.) Finally, the proortion of premature among births to mothers employed away from
ome during pregnancy was especially high. (See Table 117, p. 134.)
'These correlations point to some of the causal influences that seem to
have affected the occurrence of premature births.

* See Table 33, p. 62, for figures upon which the percentages are based.

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CAUSAL FACTORS IN' IN F A N T MORTALITY

Most of these factors depend in last analysis upon the health and
condition of the mother. In some cases the tendency toward pre
maturity appears to have been influenced by the type of birth—
whether plural or single, male or female; in other cases it seems to
have been influenced by the environment of the mother, as when she
went out to work during her pregnancy period. But the direct relation
which the mother’s health bears to prematurity was shown in the
very high proportion (39.3 per cent) of premature among infants
live born to mothers who died either at or within one month after
confinement. (See General Table 7, p. 189.) • Apparently, in many
cases, the condition that caused the mother’s death caused also the
premature birth of the child.
Summary.

The mortality among the premature was found to be five or six
times as high as that among the full-term infants, whether the rates
were compared for all infants, for those of the same sex, for single
or plural births, or for infants receiving the same type of feeding.
The excessive mortality occurred especially in the first week or the
first month; but even during the later months of the first year of
life the mortality was much greater among the premature than among
the full-term infants. Causes peculiar to early infancy and mal
formations produced the greatest excess, but other causes— gastric
and intestinal diseases, respiratory diseases, and epidemic diseases—
also caused greater mortality among the premature than among the
full-term infants.
PLURAL BIRTHS

The group of twins and triplets comprised 529, or 2.3 per cent of
the total number of live births, and included 513 twins and 16
triplets. These infants represented a total of 272 confinements;
in a number of cases one twin or one or two triplets were stillborn
and therefore were not included in the number of live births. Slightly
over 1 per cent of all confinements resulted in plural births.
An extremely high mortality rate characterized the twins and
triplets. As Table 63 shows, this group of infants had a rate of 362.9,
or 3.45 times that of the single births (105.3).
Nevertheless, the fact that less than one-half of all the twins and
triplets born died before their first birthday indicates that the total
number of survivors at the end of the first year was greater than it
would have been if these confinements had resulted in single instead
of in plural births. From each 1,000 confinements resulting in single
births, both live births and stillbirths, 865 infants were found to
have survived the first year of life. At the mortality rates that
prevailed for plural births, however, from 1,000 confinements re
sulting in the birth of twins or triplets, both live and still born, 1,212
infants would have survived the first year of life. The proportion
of survivors at the end of one year from confinements resulting in
plural births was one-third greater than that of survivors at the end
of one year from an equal number of confinements resulting in single
births. Since, however, only about 1 per cent of the confinements
resulted in the birth of twins or triplets, the occurrence of such births
did not make any considerable addition to the number of infants
who lived to become 1 year of age.

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TYPE OP BIRTH
T

able

6 3 .—

Infant mortality rates fo r single and 'plural births; live births in eight
cities
Infant
deaths

Live
births

Number at the birth

Infant
mortality
rates1

22,967

2,555

111.2

22,438
529
513
16

2,363
192
181
11

105.3
362.9
352.8

1 Not shown where base is less than 100.

Causes o f death.

The mortality from the principal causes of death among the twins
and triplets, in comparison with that among the single-born infants,
is shown in Table 64. Slightly over half the deaths of twins and
triplets were ascribed to causes peculiar to early infancy. Their
mortality rate from these causes was 187.1, or nearly six times that
of the single-born infants (32.6). From gastric and intestinal diseases
the rate for twins and triplets was 87, nearly three times as high as
the figure for single-born infants, which was only 31.1. From respira
tory diseases the mortality was twice as high, from the group of
épidémie diseases two and one-half times as high, and from all other
causes twice as high as among single-born infants.
.T

able

6 4 .—

Infant mortality rates, by cause of death and term, for single and plural
births; live births in eight cities 1
Infant mortality rates1
Plural births

Single births

Total

Full
term

Prema Total
ture

Full
term

Prema
ture

All causes.____________ _______________ ______

3 6 2 .9

2 8 5 .0

6 2 3 .0

1 05 .3

8 4 .3

5 3 0 .9

Gastric and intestinal diseases______________________
Respiratory diseases_____ _________________________
Malformations................•_______ _____ _____________
Early infancy_________ ________________ ___________
Epidemics and other communicable diseases_________
External causes___ ________________ _______________
Diseases ill defined and unknown______ _______ ____
Other causes_______________________ __________

8 7 .0
4 1 .6
5 .7
187 .1
1 8 .9
1 .9
3 .8
1 7 .0

100 .7
3 9 .3
4 .9
9 0 .9
2 2 .1
2 .5
4 ,9
19L7

4 1 .0
4 9 .2
8 .2
5 0 8 .2
8 .2

3 1 .1
19.1
4 .3
3 2 .6
6 .8
.6
2 .5
8 .5

3 0 .3
1 8 .6
3 .6
1 4 .9
6 .3
.6
2 .1
7 .8

4 4 .4
2 7 .0
1 8 .3
3 9 2 .9
1 5 .4
1 .0
9 .7
2 2 .2

Cause of death

8 .2

1The numbers of births on which these figures are based were as follows: Plural—-529, of which 407 were
fullterm and 122 were premature; single—22,438, of which 21,352 were full term and 1,036 were premature.

Neonatal mortality.

The deaths during the first month among the twins and triplets
were 172 per 1,000 live births, as compared with a rate for the singleJborn infants of only 41.8. This difference reflects the differences in
the incidence of mortality from causes peculiar to early infancy.
(See General Table 57, p 208.)

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CAUSAL FACTORS IN IN F A N T MORTALITY

Prematurity.

The high mortality both during the first month and from causes
peculiar to early infancy is explained in part by the much larger
proportion of prematurely born among the twins and triplets than
among the other infants. Of the plural births 22.9 per cent and of
the single births only 4.6 per cent were premature. Nearly five
times as many proportionately were prematurely born among the
twins and triplets as among the single-born babies.
Nevertheless, when the mortality rates for the full-term, as well
as for the premature, plural and single births were compared it was
found that in both cases the plural had a markedly higher mortality
than the single. Among the infants reported as born at term the
rate for the plural was 285, or over three times that for the single
(84.3). Among those reported as born prematurely, though both
plural and single had very high rates (623 for the former and 531 for
the latter), the plural appear still to have been at a distinct dis
advantage. Evidently, though the fact of premature birth alone
resulted in a high mortality rate, the twins and triplets among
both the full-term and the prematurely bom were under a handicap.
Causes o f death and prematurity.

The rates of death from the principal causes for the infants of
single and plural full-term and premature birth are also given in
Table 64. Among the infants born at term, differences in favor of
the single appear for every cause of death. The contrast is especially
noteworthy in the case of the rate from gastric and intestinal diseases,
which was over three times as high for the twins and triplets as for'
the single-born infants. The excess mortality of the former group
from these diseases was due in part to the fact, shown in the next
subsection, that more of them than of the single-born babies were
exposed to the hazards arising from artificial feeding.
The fact that mortality from causes peculiar to early infancy was
six times as high among the full-term twins and triplets as among the
single full-term infants must perhaps be explained largely in terms of
lesser vitality at birth, the causes of which are not fully understood.
This lack of vitality may also have played a part in the mortality of
full-term twins and triplets from respiratory, epidemic, and other
diseases, which was likewise considerably higher than among single
infants born at term.
The difference between the rates for single and plural premature
infants was due largely „to a difference in the mortality from causes
peculiar to early infancy. In fact, with the exception of respiratory
diseases, deaths from the other causes were more prevalent among
infants of single than among those of plural birth; but these rates
were based on relatively few cases— too few to justify a definite con
clusion on this point.
Type o f feeding.

Artificial food was used much more commonly for twins and triplets,
than for single-born infants. During the first month, for example,
26.3 per cent of the former as compared with only 9.8 per cent of the
latter were artificially fed. And of the total months lived up to the
end of the ninth, 45.1 per cent of those lived by the former as compared

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TYPE OF BIRTH

irai

with only 24.5 per cent of those lived by the latter were months of
artificial feeding. (See General Tables 49, p. 205 and 58, p. 208.)
The reasons for the greater prevalence of exclusively artificial
feeding among the twins and triplets doubtless include inability of a
larger proportion of their mothers to satisfy the requirements of two
or three babies than of other mothers to satisfy the requirements of
one. Since mothers are usually reluctant to give one twin the advantage of the other in type of feeding, the weaning of one meant, in
most cases, the weaning of both. Another factor that may have
affected the prevalence of artificial feeding among the twins and trip
lets was the tendency toward the giving of artificial food to the pre
maturely born, a group to which, as already stated, nearly one-fourth
of the twins and triplets belonged. (See General Tables 49, p. 20^1
and 59, p. 209.)
**sm
Since the artificially-fed infants, as will be shown later (pp. 8 9 -1 0 3 )^
had a death rate that averaged between three and four times that for t h ^
breast-fed infants, the relatively greater prevalence of artificial feed-«^
ing among the twins and triplets meant, of itself, greater m ortality^
among them. The question then arises, how much of the ex cesso
mortality among the twins and triplets was due to the greater ten-?£j
dency to give them artificial food and how much would have remained^
if there had been no differences between the single and the plural births i-;
in respect to type of feeding?
In the whole group the mortality among the twins and triplets, P
as Table 65 shows, was 3.45 times that among the single-born infants.
In other words, the actual deaths among the twins and triplets were P
3.45 times the number that would have occurred if the rates that P
prevailed among single babies had prevailed among them. In the
group of infants who died before they were fed the mortality among t:
the twins and triplets was 4.19 times that among the single-born C
infants. When the actual number of deaths among the twins and
triplets who lived long enough to be fed was compared with the
number expected at the rate prevailing among the single-born babies ^
who lived to be fed, the former was found to be 3.25 times the latter.
But when the actual number of deaths among these twins and
triplets was compared with the number expected at the rates pre
vailing among the single-born infants who received the same kmds
of feeding during corresponding months of life, the ratio was reduced
to 2.88. In other words, when allowance was made for differences in
the type of feeding received the ratio between the mortality rates for
infants of plural and of single birth was reduced by about one-ninth.

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M Q iR.T A T .T T V

T able 65.—-Relative mortality among plural and single births, when effect o f differ
ences in term and in type o f feeding is eliminated; infants in eight cities
Deaths of twins and triplets
Expected at average rates for single births—

Type of feeding and term
Actual

Expected at
average rates
for all single
births

Num
ber
T o t a l...!..............
Not fed_____________
Total fed........... .
Breastfed................
Partly breast fed......... ..
Artificially fed.________
Full term.................. .
Not fed_______ ____
Total fed......................
Breastfed________
Partly breast fed___
Artificially fed..........
Premature________ ______
Not fed___________ ____
Total fed.............. ......
Breastfed_________
Partly breast fed___
Artificially fed..........

Of the same
term

Ratio

Num
ber

Ratio

Num
ber

9 9 .1 0

1 .9 4

192

55.71

3 .4 5

49
143

11. 7a
4 4 .0 1

4 .1 9
3 .2 5

33
26
84
116

3 4 .3 3

3 .3 8

9
107
20
20
67
76
40
36
13

6
17

While receiving
the same type
of feeding

6 4 .7 7

1 .1 7

. Of the same
term while
receiving the
same type of
feeding

Ratio

Num
ber

6 1 .3 4

3 .1 3

102 .62

1 .8 7

11.70
4 9 .6 4

4 .1 9
2 .8 8

3 9 .0 6
6 3 .5 6

1 .2 5
2 .2 5

8 .5 3
6 .4 6
3 4 .6 5

3 .8 7
4 .0 2
2 .4 2

1 5 .8 2
5 .4 5
4 2 .2 9

2 .0 9
4 .7 7
1 .9 9

Ratio

4 0 .7 2

2 .8 5

3 .7 3
3 6 .9 9
6 .0 5
5 .2 0
2 5 .7 4

2. 4 l
2 .8 9
3 .3 1
3 .8 5
2 .6 0

6 1 .9 0

1 .2 3

3 5 .3 3
26. £7
9 .7 7
.2 5
1 6 .5 5

1.1 3
1 .3 5
1 .3 3
2 4 .00
1 .0 3

In the group of babies who were wholly breast fed, the death rate
among the twins and triplets was 3.87 times that among the singlebom babies. In the group of artificially-fed infants, on the other
band, the mortality among the twins and triplets was only 2.42 times
that among the single-born babies. The fact of artificial feeding
alone seems to have involved such an extra hazard that among the
artificially fed the high mortality of twins and triplets became rela
tively less important. Nevertheless, a marked disadvantage was
associated with plural birth both for breast-fed and for artificiallyfed infants.
Prematurity and type o f feeding.

Since a larger proportion of prematurely bom infants were artifi
cially fed than of those bom at term, the discussion of the relative
mortality of plural as compared with that of singlev-born infants
should take into account this overlapping of the groups' The infants
classed as “ not fed ” were nearly all prematurely born ; and the exces
sive mortality among the “ not fed ” twins and triplets is seen upon
analysis to have depended largely upon the disproportionate number
of this group who were prematurely bom . When comparison was
made for the “ not fed ” group between the mortality rates for infants
of full-term plural and full-term single birth and between those for
infants of premature plural and premature single birth the ratio of
the mortality of the plural to that of the single was found to be only

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TYPE OP BIRTH

1.25. For the group of infants who lived to be fed a similar compari
son between death rates of plural and single of the same term re
ceiving the same type of feeding reduced the ratio of the mortality
rate of infants of plural birth to that of the single born from 2.88 to
2.25. In the entire group, when allowance was made for both prema
turity and type of feeding, the ratio of the mortality among infants
of plural birth to that of single-bom infants was reduced from 3.45
to 1.87. In other words, even after full weight was given both these
other factors, the twins and triplets had a death rate nearly twice as
high as that of the single-born infants.
Furthermore, among the infants born at term who lived long
enough to be fed— a group in which the obvious handicap of prema
turity was not a factor— the plural had a mortality rate nearly three
times that of the single even after allowance was made for the larger
proportion of the former who were artificially fed.
Other factors.

Since on analysis significant correlations between the occurrence
of twins and triplets and order of birth and age of mother were found,
study should be made of the possible influence of. these factors in
causing higher mortality among plural births. The interrelations
between the occurrence of plural births and nationality and economic
factors should also be examined.
Order o f birth.— A larger proportion of the plural than of the single
births were fifth and later in order— 34 per cent as compared with
25.8 per cent. (See General Table 61, p. 209. Compare also Text
Table 35, p. 53.) Since the mortality among the births fifth and later
in order was higher than the average rate (p. 48), the excess mortality
among the plural as compared with the single infants seems to have
been partially due to the overweighting of the group of twins and
triplets with infants of these late orders. But this influence was
found upon analysis to have been relatively slight. When the mor
tality of plural was compared with that of single infants, order for
order, the average ratio between the rates was reduced from 3.45 only
to 3.37. (See General Table 62, p. 210.)
Age o f mother.—Almost the same proportion of the single as of
the plural births were to mothers under 20 or to those 35 years of age
and over— 22.8 per cent as compared with 22.7 per cent. (See
General Table 60, p. 209.) Compare Text Table 20, p. 44.) The
mortality rates for infants born to mothers under 20, as well as for
those bom to mothers 35 and over, were higher than those for the
babies of mothers between 20 and 35 years of age (p. 35). When
the rates were compared for plural and single births to mothers of
the same ages the ratio was raised from 3.45 to 3.48. (See General
Table 62, p. 210.)
When the effects of both age of mother and order of birth were
eliminated, and the death rates for plural and single births were
compared, order for order and age of mother for age of mother, the
ratio between them was practically identical with that found when
order of birth alone was eliminated (3.37). (See General Table 62,
J5T216.)
.
Color and nationality o f mother and economicfactors.—An analysis of
the prevalence of plural births to mothers of the several race and
nationality groups showed no marked or significant differences in the

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CAUSAL FACTORS IN IN F A N T MORTALITY

proportions of twins and triplets. (See General Table 63, p. 210.)
Nor were significant differences found in the proportions of plural
births to mothers of the different earnings groups. (See General
Table 64, p. 211.) These factors seem to have played no part in the
high mortality among plural births.
M ortality among pairs o f twins.

An analysis of the mortality among the pairs of twins reveals
the interesting fact that the death of one member of a pair was cor
related with the death of the other and the survival of one with the
survival of the other. For the sake of simplicity in statement, only
the 247 pairs of which both members were born alive are considered
in this discussion. Of these 494 live-bom twins 176 died under 1
year of age, giving a mortality rate of 356.3 for this group. If the
survival or death of one twin of a pair had been entirely independent
of that of the other, according to the mathematics of chance, in 31
of the 247 cases both twins would have died, in 102 both twins would
have survived, and in 113 one twin would have died and one would
have survived.6 Actually, instead of 31 pairs, 63 were found in
which both died. Hence, one of a pair of twins of which the other
had died, appears to have been more likely to die also than one of a
pair of which the other had survived. (See General Table 56, p. 207.)
This fact is explained in part by the tendency of twins both to be
born prematurely or both to be born at term. Among the 247 pairs
only 1 was found in which one twin was reported born at term and
the other prematurely. When, therefore, one twin died because of
premature birth the other, also, had been born prematurely, and
was subject to a much heavier risk of dying than if born at term.
But even after allowance was made for the tendency of both twins
of a pair to be born after the same period of gestation, a considerably
larger number of pairs were found in which both died than would
have been expected if the death of one had not been in some other
way associated with the death of the other. Among the 55 pre
maturely born pairs of twins, there were 29 cases in which both in
fants died, as compared with 20 expected at the average rate of
mortality for this group on the hypothesis that the death or sur
vival of one was independent of tnat of the other; and among the
191 pairs born at term there were 34 cases in which both died, as
compared with 16 expected on this hypothesis.
In further explanation of this relationship may be mentioned the
fact that the twins were of the same sex in about two-thirds of the
cases. In such cases the greater mortality among male than among
female infants would result in both twins dying in more cases than
would be expected at average rates for the entire group.
Other explanations come easily to mind. The type of feeding
that one twin received was probably, as a rule, the same as that
received by the other. Mothers, it has already been noted, are
usually reluctant to give one twin the advantage of the other in the
type of feeding; when, therefore, a mother was obliged because of
her own ill-health or for any other reason to give up breast feeding
6P
probability of dying (.3563) and q is the probability of surviving the first year (.6437), then the
probability of both twins dying is p 2, of both twins surviving, g2, and of one tw in dying and the other sury m n g , 2i>9. These figures multiplied b y n (247, the number of pairs) give the values stated in the text
(np2—31.36; 2np q—113.29;
=102.34). It will be noted that the process of rounding off to the nearest whole
unit leaves one pair unaccounted for.

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TYPE OP BIRTH

for one infant, she was very likely to give it up for both. If one
twin, then, was exposed to the greater risk associated with artificial
feeding the other was likely to have been so exposed.
Furthermore, the environment surrounding one of a pair of twins
was in practically all cases probably more or less similar to, if not
identical with, that surrounding the other. If one twin was sub
jected to good or to bad environmental conditions— the conditions
associated, for example, with earnings of the father, nationality of
the mother, the mother’s employment, or housing congestion— the
other twin in aH probability had the same advantages or disadvan
tages.
Causes o f plural births.

The data under consideration throw little light upon the causes
of plural births. These causes are biological or physiological con
ditions that affect the ovum and that are com m only regarded as
hereditary.7
&
The mother of each infant included in the study reported not only
on the birth of that infant but also on the number of her previous
pregnancies and as to whether they had resulted in single or in
plural births. The proportion of all the pregnancies of these mothers
that had resulted in the birth of twins or triplets was practically
the same as that of the pregnancies that resulted in plural births in
the selected year, and the number of mothers who had had one or
more such births was 725, or 3.3 per cent of the total. (See General
I able 65, p. 211.) But while only 1 per cent of all the pregnancies
included m the study resulted in the birth of twins or triplets, of
those that followed plural births 3 per cent resulted in such births.
Since the proportion of twins and triplets born to mothers shown
by previous plural births to possess hereditary or other physio
logical characteristics which make such births possible was only
three times as great as the proportion among all births, the inference
might be drawn that some such characteristic was possessed by onethird of all the mothers.8 This inference, however, would rest upon
the assumption that there was no physiological cause for a greater
prevalence of plural births among births resulting from later as com
pared with earlier pregnancies. For if twins and triplets were more
likely to occur in later pregnancies the larger proportion of such
births among pregnancies following plural births might have been
due in part to the fact that these pregnancies were on an average of
later orders.
When the comparison was made order for order (after the first),
the actual number of pregnancies resulting in plural births among
pregnancies of mothers who had previously given birth to twins or
triplets was found to be only two and one-half (2.45) times the
number of pregnancies expected so to result at the rates for the
occurrence of first plural births among births of each order. Hence
unless the occurrence of one plural birth had a definite influence per
se upon the occurrence of a later plural birth, either to make it less
- 4 £ u inzili6’ F'S H^ndbuch der medizinischen Statistik, pp. 68-69. Jena, 1906.
The calculation is follows: Let x be the proportion of births to mothers having a hereditary or other

96515°—25t-----7

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or to make it more likely, the hereditary or other physiological pre
disposition to twins must have been widely diffused, affecting twofifths of the mothers.9
Summary.

Twins and triplets had a death rate nearly three and one-half times
as high as that of single-bom infants. Their mortality from causes
pecuhar to early infancy was especially high, but their rates from
other causes were also markedly above those for single-born infants.
Of the twins and triplets over one-fifth (22.9 per cept), as compared
with less than 5 per cent of the single babies, were prematurely born.
This disproportionate number of premature births seems to have
accounted for a considerable part of the excessive mortality of the
twins and triplets. Another element in their high death rate was
the large proportion who were artificially fed. But even when both
these factors were allowed for the mortality among the plural ;was
nearly twice that among the single-born infants. Evidently some
other element was a factor in producing this high mortality.
In case of the larger proportion of prematurely bom infants the
fact of plural birth may itself have been the causal factor. If so,
the reduction of the high infant mortality rate would have required
the prevention of prematurity among the twins and triplets. A
decrease in early weaning and a more careful observance of safe
guards in connection with the giving of artificial food would also, it
appears, have reduced their high mortality.
TYPE OF DELIVERY

Information concerning the delivery by Caesarean section or delivery'
by means of instruments was obtained for births in Baltimore. The
results of this inquiry are given in Table 66. Of the total number of
infants born alive the mothers of 15 (one-tenth of 1 per cent) were
delivered by Caesarean section. Three of these babies died under 1
year of age. The mothers of 748 (6.9 per cent) had instrumental
delivery. For these the infant mortality rate was 120.3, considerably
higher than that for infants of mothers whose deliveries were normal
(102.1).
T a b l e 6 6 . — Infant mortality rates, by type o f delivery; live births in Baltimore

Infant deaths

Type of delivery

Live
births

All causes

Injuries at birth

Other causes

Infant
Infant
Infant
Num mortality
Num mortality
Num mortality
ber
ber
ber
rates
rates
rates
Total__________ _____________

10,797

1,117

103.5

4.1

1,073

99.4

Instrumental delivery..____________

748
15
“ 10,034

90
3
1,024

120.3

28.1

92.2

102.1

2.3

69
3
1,001

Normal delivery................... ..........

99.iL

° Including 31 not reported.
9 This analysis permits a correction in the proportion as calculated in footnote 8. Here 2.45 x = 1; and
x = 40.8 per cent.

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As would be expected for the infants of mothers delivered b y means
of instruments the death rate from causes peculiar to early infancy
was considerably above that for other infants— 60.2 as compared
with 36. This excessive mortality was found on analysis to have
been largely concentrated in the subgroup “ injuries at birth,” the
rate for which was especially high— 28.1 as compared with 2.3 for
normal births. All the other causes included in the group “ early
infancy” had a combined rate practically identical with that for
normal births— 32.1 as compared with 33.7.
The mortality rate from all causes other than those peculiar to
early infancy in the group of instrumental-delivery births was slightly
lower than that for normal births— 60.2 as compared with 65.8.
In passing it is interesting to note that a markedly smaller pro
portion of the instrumental-delivery births than of all others occurred
in families in which the father’s earnings were less than $650, the
proportions being 29.8 per cent and 44.9 per cent, respectively.
(See General Table 66, p. 211.)

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TYP E OF F E E D IN G 1

Information in regard to the type of feeding during each month
of the first year of life was obtained for the 22,422 infants who lived
to be fed.2 These data make it possible to compare the number of
deaths with the time lived by infants receiving each type of feeding,
a procedure which yields statistically sound rates of mortality for the
different types (p. 13.) This procedure also permits taking into
account the varying mortality rates in the different months of life
and the varying ages at which the infants were transferred from
breast to partially or exclusively artificial feeding.
The kinds of feeding were classified into three types, exclusively
breast, exclusively artificial, and partly breast and partly artificial.
This grouping was not wholly satisfactory. The infants who re
ceived partially and exclusively artificial feeding were not classified
in detail according to the character of the food given, and hence
the analysis of the effect of types of feeding on infant mortality made’
in the present study had to be confined to the differences between
exclusively breast and exclusively artificial feeding and between^
partially breast feeding and each of the other two groups, irrespective
of the character of the artificial food.
T a b l e 67 .— Type of feeding, by month^of life; infants in eight cities
Infants surviving at beginning of specified month of life
Exclusively breast
fed during month

Month of life

Partly breast fed
during month

Total
Number Per cent Number
First...........................
Second............. .........
Third____ ____ _____
Fourth.......... .............
Fifth...........................
Sixth_____ ______
Seventh____________
Eighth........................
Ninth______ ____
Tenth______________
Eleventh..... ........... __
Twelfth............... ......

1 22,422
21,939
21, 735
21, 560
21, 387
21, 222
21,066
20,934
20,812
20,693
20, 584
20,504

19,438
17,178
15,509
13,516
12,263
10,969
8,641
7,343
5,853
4,248
3,278
2,736

86.7
78.3
71.4
62.7
57.3
51.7
41.0
35.1
28.1
20.5
15.9
13.3

686
1,294
1,786
2,668
3,317
4,098
5,801
6,671
7,684
8,591
9,062
9,145

Exclusively arti
ficially fed during
month

Per cent Number
3.1
5.9
8.2
12.4
15.5
19.3
27.5
31.9
36.9
41.5
44.0
44.6

2,287
3,457
4,431
5,366
5,797
6,145
6,615
6,911
7,268
7,845
8,235
8,616

Not re
ported

Per cent
10.2
15.8
20.4
24.9
27.1
29.0
31.4
33.0
34.9
37.9
- 40.0
42.0

11
10
9
10
10
10
9
9
7
9
9
7

1 Excluding 545 infants who died not fed.

P R E VALEN C E O F B R EAST A N D ARTIFICIAL F E E D IN G

Table 67 shows the increase in prevalence of artificial feeding from
month to month during the first year of life. In the first month
86.7 per cent of the infants were breast fed, 3.1 per cent were partly
breast fed, and 10.2 per cent were exclusively artificially fed. In
the third month the proportion exclusively breast fed had fallen t
1922^ summary of this cliaPter was published in the American Journal of Hygiene, vol. 2, no. 6 (November,
1 Infants who died without being fed numbered 545, 2.4 per cent of the total.

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TYPE OP FEEDING

71.4, and that artificially fed had doubled, reaching 20.4 per cent.
B y the sixth month the proportion exclusively breast fed was only
slightly over half, and that artificially fed had risen to nearly threetenths. B y the ninth month only 28.1 per cent were exclusively
breast fed, the proportion partly breast fed had increased to 36.9
per cent, and the proportion exclusively artificially fed had increased
to 34.9 per cent. At the end of the first year of life only 13.3 per cent
of the infants continued to be exclusively breast fed; the proportion
partly breast fed had risen to 44.6 per cent and that wholly artifi
cially fed to 42 per cent. Up to the ninth month the proportion of
artificially-fed exceeded that of partly breast-fed infants. From the
ninth to the twelfth this relative position was reversed, and the
proportion partly breast fed was slightly greater than that exclu
sively artificially fed. The greatest number of transfers from
exclusively breast to partly breast or to artificial feeding took place
between the sixth and. the seventh month.
These figures can be summed up in convenient fashion in terms of
months lived b y infants who received each type of feeding. When
the figures for the first nine months only are taken for this purpose
— since, as will be shown later (p. 90), the type of feeding in these
months was of greater importance than in the remainder of the first
year of life— it was found that of the 192,212.5 months lived by the
infants 57.4 per cent were months of breast feeding, 17.6 per cent
were months of partially breast feeding and 24.9 per cent were
months of artificial feeding. Thus not far from three-fifths of the
months lived up to and including the ninth were months of breast
feeding, and approximately one-fourth were months of artificial
feeding.
M O N T H L Y D E A T H R A T E S , B Y TY P E OF F E E D IN G

In Table 68 monthly death rates are shown for each month of the
first year of life. By comparing the rates in each month for the
three types of feeding the relations between these rates are made clear.
In the first month mortality among the artificially-fed infants was
over three times that among the breast fed; in the second month it
was four times, in the third nearly six times, in the fourth, fifth, sixth,
and seventh months over five times, in the eighth four times, and in
the ninth slightly over three times that among the breast-fed infants.
After the ninth month the relative advantage of breast feeding was
much less.
The relation between the rates for partly breast-fed babies and
those for infants in the other two groups is also shown. In each of
the first eight months the mortality among the partly breast-fed was
higher than that among the wholly breast-fed and lower than that
among the artificially-fed infants. In the first month it was twice
that for exclusively breast-fed babies; it rose to about two and one-half
times in the second month; in the third it was over three times, in the
fourth nearly three times, in the fifth nearly twice, in the sixth nearly
three times, in the seventh twice, in the eighth slightly greater than,
„and in the ninth slightly less than the rate for babies who were wholly
breast fed. During the first nine months the rate for the partly
breast-fed averaged about twice as high as that for the wholly breast
fed infants. For the same period the mortality among the babies
who were exclusively artificially fed averaged about three times as
high as that among the partly breast fed.

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T

able

6 8 .—

Monthly death rates, by type o f feeding; infants in eight cities 1
Monthly death rates
Month of life

First_______ ______________ ______ ________. _______ _
Second________________________________ ___________
T h ird........................................................................ ........
Fourth.......................................... ............ .......................
Fifth...............................................................................
Sixth__________ ________ ________________ ____ ______
Seventh— ____ ___________ _____ _______ ___________
Eighth....... ................................................................ ........
Ninth________ ________ ________ .......................... ........
Tenth_________________ _______ __ ____ ______ _____ _
Eleventh_______________ __________________________
Twelfth___________________________________________

All types
of feeding

Exclu
sively
breast fed

Partly
breast fed

*44.8
9.3
8.1
8.0
7.7
7.4
6.3
5.8
5.7
5.3
3.9
4.5

16.9
5.8
3.7
3.4
3.3
2.1
1.9
2.9
3.2
3.8
2.4
4.4

36.4
14.7
12.9
9.0
5.7
5.9
4.0
3.3
2.9
2.3
2.5
2.7

Exclu
sively
artificially
fed
54.7
24.6
21:2
19.2
18.1
17.7
14.1
11.3
10.7
9.3
6.0
6.4

1 For basic figures see General Table 67, p. 212.
* The rate per 1,000 fed is 21.5; 545 infants died not fed.

A convenient method of summing up the relative disadvantage of
artificial feeding, shown in Table 69, is to compare the deaths which
actually occurred among the artificially-fed infants with the number
tha't would have occurred if the rates found for the breast fed had
prevailed among them. In this comparison allowance can be made
for the decrease in mortality with increase in age. When the monthly
death rates for breast-fed babies were applied to the infants who were
artificially fed in the corresponding months, it was found that instead
of the 1,047 deaths that actually occurred among the artificially-fed
infants, only 268.6 would have been expected. In other words, the
actual deaths were nearly four times those that would have been
expected at the rates prevailing for the babies who were breast fed.
When a similar comparison was made of the number of deaths that
actually occurred among the partly breast-fed infants with the number
that would have been expected if the rates for the wholly breast fed
had prevailed, it was found that only 203.8 deaths would have
occurred instead of 269. The mortality among the partly breast-fed,
that is, averaged 1.32 times as high as that among the wholly breast
fed infants.
T

6 9 . — Mortality among partly breast-fed and among artificially-fed infants as
compared with that o f breast-fed infants, during first nine and last three months of
the first year; infants in eight cities

able

Deaths of partly breast-fed
infants

Period
Actual

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Expected
at rates Ratio of
for breast actual
to
fed in
expected
same
months

Deaths of artificially-fed
infants

Actual

Expected
at rates Ratio of
for breast actual
to
fed in
expected
same
months

269

203.8

1.32

1,047

268.6

3.90

201
68

109.1
94.7

1.84
.72

870
177

181.1
87.5

4.80
2; 03

TYPE OF FEEDING

When the comparison was limited to the first nine months of life,
however, the excess mortality both among artificially-fed and among
partly breast-fed infants appeared more marked. Thus during the
first nine months 870 deaths of artificially-fed infants occurred, as
compared with only 181.1 that would have been expected at the
rates prevailing for those who were breast fed. In other words,
during this period the rates of mortality for the artificially-fed aver
aged 4.8 times as high as for the breast-fed babies. Among the
partly breast fed 201 deaths occurred during the first nine months,
as compared with only 109.1 expected on the basis of the rates pre
vailing for the wholly breast fed. The monthly death rates for the
partly breast-fed babies, that is, averaged not quite twice (1.84
times) as high as those for the more favored group of infants who
received exclusively breast feeding.
IN FLU E N C E O F C H A N G E S IN F E E D IN G

The data secured on this subject also throw light upon the relative
advantage or disadvantage of a change from breast feeding to partly
or wholly artificial feeding at different times during the first year of
life. The contrast between the mortality among infants who in a
iven month ceased to be exclusively breast fed and that among
abies who continued to be breast fed is shown in Table 70 in the
form of a comparison between the average monthly death rates from
each month to the end of the first year for two groups of infants,
those whose breast feeding ceased with or was first supplemented
during the month and those whose breast feeding continued to the
end oi the year.
The average monthly death rates from the second, third, fourth,
fifth, and sixth months to the end of the first year among infants
whose breast feeding ceased or was first supplemented in these
months were higher than the corresponding rates among those who
were exclusively breast fed to the end of the year. When the change
from breast to partially or exclusively artificial feeding took place m
the seventh month or afterwards, however, the average death rates
for the subsequent months of the year were slightly less than the
corresponding rates for babies who were breast fed up to the end of
the year.
A comparison of these average rates with the mortality in the
different months among infants who were breast fed during those
months indicates not only that the breast-fed babies had rates in the
seventh and eighth months below the average from the seventh or
eighth month to the end. of the year for babies who were either partly
or wholly weaned during that period, but also that they had rates
lower than the average monthly rate for infants who were exclusively
breast fed during these later months of the first year.

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92
T

CAUSAL FACTORS IN IN F A N T MORTALITY

7 0 .— Relative advantage or disadvantage o f a change from exclusively breast
feeding, as shown by average monthly death rates from time o f change to end o f first
year o f life, by month o f life in which change was made; infants in eight cities

able

Infants whose breast feeding ceased
or was first supplemented in
specified month

•

Month of life

First .............................................................
Second...........................................................
Third.............................................................
Fourth_____________ ___________________
Fifth____ ____ _________________________
Sixth..............................................................
Seventh_______________________________
Eighth................... .......................................
Ninth................... .........................................
Tenth and later__ ______ _______________

Subsequent
months
lived to
end of
first year

17,509
19,811
14,915
16,915
9,480
8,652
13,722
6,357
5,848
7,190

Deaths

92
260
155
111
44
36
36
21
14
12

Infants exclusively
breast fed

Average
monthly
Monthly
Average death rate death
rate
monthly
from
specified
death rate specified in month
month to
end of year
12.3
13.1
10.4
6.6
4.6
4.2
2.6
3.3
2.4
1.7

4.5
3.3
3.1
3.0
3.0
3.0
3.1
3.3
3.4
3.5

’ 16.9
5.8
3.7
3.4
3.3
2.1
1.9
2.9
3.2
3.5

1 The rate for the first month is not exactly comparable with those for later months. The figures for the
secondmonth,forexample,includeinfants who were exclusively breastfed in the first but either partially
or exclusively artificially fed in the second; the figure for the first month, however, includés only infante
who were partially breast fed during the greater part of the month, and these may or may not have received
exclusively breast feeding for a period not exceeding two weeks. Infants who received exclusively breast
feeding for less than two weeks and were then transferred to exclusively artificial feeding, on the other
hand, are not included. These differences may explain the slightly lower rate found for the first month
as compared with the second.

Table 71 throws light on the relative advantage or disadvantage
of weaning at different times during the first year, b y comparing the
average monthly death rates from the month of weaning to the end
of the first year of infants whose wholly artificial feeding commenced
in a given month with those of infants who were exclusively breast
fed during the same periods.3
The figures show higher mortality rates among infants who were
weaned before the eighth month than among infants who continued
to be breast fed. For infants weaned after the eighth month, how
ever, the rates were not substantially higher than for those who con
tinued to be breast fed. Unfortunately the fact that in the data
available for study the period of observation was cut off at one year
caused the number of months and of deaths to diminish rapidly, with
the result that the numbers, especially for changes after the eighth
month, were small.
» In Table 71 infants who were exclusively artificially fed at some time during the first year of life were
classified according to the month in which exclusively artificial feeding began; in Table 70 infants who
were exclusively breast fed at some time during the first year of life were classified according to the month
in which breast feeding ceased or ceased to be exclusive.

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TYPE OF FEEDING

T a b l e 7 1 .— Relative advantage or disadvantage o f a change to exclusively artificial

feeding, as shown by average monthly death rates from time o f change to end o f first
year o f life, by month o f life in which change was made; infants in eight cities
Infants whose exclusively artificial
feeding commenced in specified
month
Month of life
Months
lived to
end of year
F irst...................................
Second_____________ ____ __________
Third ....... ...............................
Fourth..................... .........
F ifth........ ..................................
Sixth______________ ____
Seventh_____________ ____ _____
Eighth....................................
Ninth and later............................

Average
Monthly
Average
monthly
monthly death rates death rate
in
specified
death rates to end of
month
year

Deaths

23,189
13,089
10,015
8,896
4,149
3,112
3,425
1,942
6,059

Exclusively breast-fed
infants

535
196
128
89
34
27
17
6
16

23.1
15.0
12.8
10.0
8.2
8.7
5.0
3.1
3.2

4.5
3.3
3.1
3.0
3.0
3.0
3.1
3.3
3.4

•16.9
5.8
3.7
3.4
3.3
2.1
1.9
2.9
3.4

C U M U L A TIV E IN FLU EN C E OF EAR LY ARTIFICIAL F E E D IN G

A comparison of the monthly death rates for all infants who were
exclusively artificially fed during the ninth to twelfth months— 10.7,
9.3, 6, and 6.4, respectively, as shown in Table 68—with the average
rate from the time of weaning up to the end of the year for infants
whose exclusively artificial feedmg did not begin until the ninth
or a later month— 3.2, as shown in Table 71— indicates clearly
that artificial feeding during the early months had a cumulative
effect which appeared in excessive mortality in the later months.
Table 72, which shows monthly death rates for the groups of infants
whose artificial feeding commenced in the different months up to the
ninth, brings out clearly this effect. In each month of life the mor
tality tended to be higher the longer the period of previous artificial
feedmg. For example, the rate in the fifth month for infants whose
artificial feeding commenced in the first was 24, as compared with
rates in the fifth month for those whose artificial feeding commenced
in the second of 18.7, in.the third of 18.3, in the fourth of 13.6, and
in the fifth of only 3.8.
T a b l e 72 .— Monthly death rates, by duration o f 'previous artificial feeding; infants

in eight cities 1
Monthly death
rates of
infants—
Month of
life

First._____
Second____
Third........ .
F o u rth ___
F ifth .........
Sixth_____ _
Seventh___
Eighth........
Ninth_____
Tenth.........
Eleventh. __
Twelfth___

Monthly death rates of infants artificially fed from—

Exclu Artifi
Ninth
Sec
Sev
sively cially
First
Third Fourth Fifth
Sixth
ond- month
enth Eighth month
breast
month
month
month
month
month
and
fed2
month
month
fed
later1
16.9
5.8
3.7
3.4
3.3
2.1
1.9
2.9
3.2
3.8
2.4
4.4

55.2
24.7
21.3
19.2
18.1
17.8
14.1
11.3
10.7
9.3
6.3
6.2

55.2
33.6
26.1
29.8
240
18.9
19.8
9.8
14 3
14.0
6.8
13.1

10.0
21.1
19.9
18.7
18.2
19.4
18.1
15.8
6.2
10.8
4.5

12.2
16.1
18.3
21.6
8.0
13.1
13.3
9.3
8.4
6.3

1.0
13.6
2L6
12.0
14 2
11.3
10.4
3.2
2.1

3.8
9.4
11.4
7.7
5.8
11.7
7.9
8.0

4.4
11.0
4. 5
11.2
11.3
6.9
11.5

3.5
8.7
1.7
12.3
3.5

2.6
26
5.1
5. 2

1.8
3.9
40

1 For basic figures see General Table 68, p. 214.
* The slight differences which appear between these rates and those shown in Table 68 are due to the
omission from this table of a small number of cases in which exclusively artificial feeding was begun but
was later changed to partially or exclusively breast feeding.

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CAUSAL FACTORS IN IN F A N T MORTALITY

The contrast was even more striking when the rates for the artifi
cially-fed were compared with those for the exclusively breast-fed
babies. Thus, the mortality in the fifth month prevailing among
infants who had been fed artificially from the first month or from
birth was seven times as high as that prevailing among the breast fed;
the mortality among infants who had been fed artificially from the
second month was nearly six times, from the third month five and
one-half times, and from the fourth month four times as high as
among those who had been breast fed from birth, whereas the'rate
for infants whose artificial feeding commenced in the fifth month
was only slightly greater than that for breast-fed babies. The rates
in other months of life showed, in general, similar increases with
increase in the period of previous artificial feeding. The mortality
rate for artificially-fed infants in any month, therefore, was an average
of rates for groups of infants who had received artificial and breast
feeding for periods of varying length. Other things being equal,
the longer the period of previous artificial feeding the higher was the
rate, and the longer the period of previous breast feeding the lower the
rate.
. . .
Not only was the mortality in a given month of life higher among
infants who had been artificially fed for longer periods than among
infants who had been artificially fed for shorter periods, but the
mortality in successive months among infants for whom artificial
feeding began in given months increased, relatively to that among
breast-fed infants, with the increase in the duration of previous
artificial feeding. The first-mentioned effect was due in part, as will
be shown later (pp. 96—97), to the fact that the groups of infants
who were artificially fed in the early months had more than their due
proportions of twins and triplets, for whom mortality rates were
especially high. But the increase in the relative mortality within
each group of the artificially fed as the duration of artificial feeding
increased, which was observed during the first four or five months
following the commencement of early artificial feeding, can be ex
plained only as a result of the cumulative effect of the type of feeding.
For the infants whose exclusively artificial feeding commenced in the
second month, for example, the mortality rate prevailing in that
month was 1.7 times the rate for breast-fed infants; the rate for this
group in the third month, however, was 5.7 times, and that in the
fourth month was 5.9 times the corresponding rate for breast-fed
infants. For the infants whose exclusively artificial feeding com
menced in the third month the rate was in that month 3.3 times, but in
the fourth month 4.7 times and in the fifth month 5.5 times the
corresponding rates for breast-fed infants. This increase in the
differences between the rates as the length of artificial feeding in
creased points clearly to the conclusion that the effect of the type of
feeding was cumulative.
C AU SES OF D E A T H

An analysis of the death rates by cause (as in Table 73) shows,
as would be expected, that the excess mortality among the infants
who were artificially fed was greatest from gastric and intestinal
diseases, the causes most definitely connected with improper feed
ing. For the period from the’ second to the ninth month the mor
tality from these diseases among artificially-fed babies was 11.3

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TYPE OF FEEDING

times as great as among exclusively breast-fed babies, but in the
tenth, eleventh, and twelfth month period it dropped rapidly to
only 3.5 times as great. (See General Table 67, p. 212.) During the
entire first year of life the mortality from this group of causes among
artificially-fed infants averaged 7.7 times that among breast-fed
infants. If the rates from gastric and intestinal diseases prevailing
for breast-fed had prevailed also for artificially-fed babies only 64
deaths from these causes would have occurred in the latter group,
whereas the number which actually occurred was 495.
Not only were the monthly rates from gastric and intestinal
diseases markedly higher, but those from all the other principal
causes appear to have been higher for artificially-fed than for breast
fed infants. Among the artificially fed the mortality from respir
atory diseases averaged 85 per cent higher, and the rates from mal
formations and from early infancy were four and six timps as high,
respectively. From epidemic diseases the mortality was over twice
as high. The group of “ all other causes,” including convulsions,
meningitis, and congenital heart disease, had a rate two and one-half
times as high, and that of ill-defined causes had a rate nearly five
times as high for the artificially-fed as for the breast-fed infants.
T

7 3 .— M ortality among partly breast-fed and artificially-fed infants as com
pared with that among breast-fed infants, by cause o f death; infants in eight cities

able

Deaths of infants—
Partly breast fed

Artificially fed

Cause of death
Actual

All causes_______________________
Gastric and intestinal diseases.................
Respiratory diseases.._________________
Malformations.................... .................... "
Early infancy____ 1________________ y
Epidemic and other communicable dis
eases________•___________ ________ ___
External causes________________
Diseases ill defined and unknown_______
Other causes...............................

269

Ratio
of
Expected1 actual
to ex
pected
204.0
61.9
82.7
3.7

10.6

1.3

Actual

Expected

1,047

268.4

496
185
26
165

64.2
100.4
5.9
27.1

Ratio
of
actual
to ex
pected
3.9

26.9
2.2
1.4
24.4

1Expected if the rates from each cause that prevailed among breast-fed infants had prevailed amoinrthe partly breast-fed and the artificially-fed infants.
*
6

The higher monthly rates from “ other causes” may have been
due to digestive disorders, so far as they were produced by deaths
from convulsions following upon gastric and intestinal diseases.
Similarly the group of deaths from ill-defined causes may have
included many from digestive diseases. Even under the group of
causes peculiar to early infancy, especially in case of deaths classified
as from “ congenital debility,” many deaths may have been included
which were largely the result, and fairly to be ascribed to the effect,
of improper feeding; for this term, according to the rules of classifi
cation in use by the Bureau of the Census, includes all deaths under
1 year reported as due to such vague causes as debility, marasmus,
emaciation, malassimilation— conditions which, when they appear

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CAUSAL FACTORS DST IN FA N T MORTALITY

after the first or second month of life, are probably often due to
improper feeding or to digestive disorders.
In this connection it may be noted that the mortality from con
genital debility from the second to the twelfth month among artifi
cially-fed infants was 10.7 times that among breast-fed infants, the
rate from this cause corresponding closely with the excess mortality
from gastric and intestinal diseases. On the other hand, in the first
month the mortality from this cause among the artificially-fed infants
was only 3.1 times that among breast-fed infants.
Although part of the excess mortality from congenital debility
appearing among the artificially fed was probably due to inaccurate
reports as to the cause of death, the considerable excess in their
mortality from other causes peculiar to early infancy, including pre
mature birth and injuries at birth and malformations, can be ex
plained only on the hypothesis that infants who were physically weak
were more likely to be artificially fed than were more robust infants.
The fact that such a tendency existed would not affect the conclusion,
of course, that the chances of life of these infants were greater if they
were breast fed than if they were artificially fed.
When the mortality among the partly breast-fed was compared
with that among the wholly breast-fed babies, a notably higher death
rate from gastric and intestinal diseases was found to prevail among
the former. The mortality among the partly breast-fed, though by
no means so marked as that among the artificially-fed, was 2.2 times
that among the exclusively breast-fed infants. Evidently while
partial breast feeding afforded some protection against these diseases,
it did not afford the same amount of protection as exclusively breast
feeding.
The mortality among the partly breast-fed from causes peculiar
to early infancy, also, was over twice as high as that among the wholly
breast-fed infants. For other causes of death the figures are too small
to be significant.
PLURAL B IR T H S , P R E M A T U R IT Y , AN D D E A T H OF M O T H E R

Evidence has already been presented to show that twins and
triplets, prematurely born infants, and babies whose mothers died
within the year were characterized by high mortality rates from
all causes and especially from causes peculiar to early infancy.
Since artificial feeding was especially prevalent among these infants,
the group of artificially fed was unfavorably weighted with babies
belonging to these groups in which the mortality rates from causes
other than feeding were exceptionally high. (See pp. 35, 75 and
80-81, and General Tables 49 and 9, pp. 205, 190.) Of the infants
who were artificially fed in the first month 5.5 per cent Were twins
and triplets as compared with only 1.6 per cent of those who were
breast fed in the first month. Similarly in the former group 8.2
per cent were premature as compared with only 3.1 per cent in the
latter. And in the former 2.8 per cent were infants whose mothers
died within the year as compared with only 0.3 per cent in the latter
(Compare General Tables 67 and 8, 48, and 58, pp. 212, 189, 205, 208.)
Of the months lived from birth to the ninth by infants while arti
ficially fed 3.3 per cent were lived by twins and triplets, 4.6 per cent
b y prematurely born babies, and 1.4 per cent by babies whose moth
ers died within one year after confinement, as compared with 1.1 per

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TYPE OF FEEDING

cent, 2.4 per cent, and 0.1 per cent, respectively, of the months lived
b y infants while breast fed. (Compare General Tables 4 9 and 9 , d d .
209 and 190.)
In the entire group of infants the rates for the artificially fed
averaged 3.9 times those for the breast fed. Among the twins and
triplets, according to Table 74, the mortality of the artificially fed
averaged 3.6 times, and among the single-born babies it averaged 3.8
times, as high as among the breast-fed infants. Thus if the rates for
the single and plural breast fed had applied, respectively, to the single
and plural artificially fed, instead of 1,047 deaths only 279.2 would
have occurred in the entire group of artificially-fed infants. In other
words, the mortality among artificially-fed averaged 3.75 times that
among breast-fed infants even after the influence of the overweighting
of the former group by twins and triplets was eliminated.
T able 74 .— M ortality among artificially-fed as compared with that among breast-fed’
infants, when influence o f plural births, prematurity, and death o f mothers is
eliminated; infants in eight cities
Deaths of infants artificially fed
Expected at average rates for breast-fed infants
in corresponding months—

Single and plural births,
term, death of mothers
Actual

Expected at
average rates
for breast-fed
infants in cor
responding
months

In each speci
fied group

For single and
plural births of
same term

For single and
plural births of
same term to
mothers who
died and to
mothers who
survived the
year

Num B atió1 Num
B atió1 Num
Batió 1 Num
ber
ber
ber
ber
Total.............................

1,047

Single.....................................

963

Full term.........................
Premature_____________

851
112

Plural.....................................

Full term.........................
Premature—....................

67
17

Total.............................

1,047

293.95

3.56

Full term................................
Premature________________

918
129

235.60
58.35

3.90
2.21

Total________________

1,047

283.61

3.69

Mothers died.........................
Mothers survived the year _.

34
1,013

20.27
263. 34

1.68
3.85

268.57

3.90

B atió1

279.16

3.75

304.40

3.44

320.23

3.27

256.01

3.76

279.29

3.45

295.12

3.26

228.48
50.81

3.72
2.20

241.49
53.63

3.52
2.09

25.11

3.35

25.11

3. 35

15.36
9.75

4.36
1.74

15.36
9.75

4. 36
1.74

23.15

3.63

______

1 Batió of actual to expected.

The effect of eliminating the influence of the other factors was
also found to be relatively slight. When the effect of the over
weighting of the artificially-fed group by prematurely born infants
was eliminated, the ratio of mortality among the artificially-fed to
that among breast-fed infants was reduced only from 3.90 to 3.56;
and similarly when the influence of the overweighting by infants
whose mothers died was eliminated, the ratio was reduced only
from 3.90 to 3.69.

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CAUSAL FACTORS IN' iisTFANT MORTALITY

Since a much larger proportion of plural than of single births were
premature, the reduction m the ratio between the number of deaths
m the two groups resulting from eliminating the influence of pre
maturity may in part duplicate that resulting from eliminating the
influence of plural birth. Nevertheless, when the influence of both
these factors was eliminated, the ratio was reduced only from 3.90
to 3.44. When the influence of all three factors was eliminated,
regardless of overlapping of the groups, the mortality among artifi
cially-fed infants still averaged 3.27 times that among breast-fed
infants.
This analysis shows clearly that the effect of the overweighting of
the group of artificially fed by infants belonging to groups which had
high mortality rates was of minor importance as compared with the
.marked excess mortality associated directly with the kind of feeding.
Reference has already been made to the influence which the tend
ency to feed artificially infants in certain groups characterized by
high mortality rates in larger proportions or beginning at earlier
ages than other infants may have nad in increasing the apparently
cumulative effect of the type of feeding. Of the infants who were
artificially fed beginning in the first month 12.4 per cent either were
prematurely born or were twins or triplets, as compared with an
average of 7.3 per cent of those for wnom artificial feeding began
in the second and third, 5 per cent of those for whom it began in the
fourth to the seventh, and only 3.8 per cent of those for whom it
began in the eighth to the twelfth month.
Table 75 shows the monthly death rates for groups that were not
affected b y this influence— the artificiafly-fed, single-born infants who
were bom at term and whose mothers lived throughout the year
following their birth, classified according to the month when artifi
cial feeding commenced. The effect of eliminating the three groups
previously discussed was to reduce materially the ratio between
the mortality among infants who had been artificially fed from the
first month and that among infants whose artificial feeding commenced
later. This elimination, however, did not alter the general conclusion
previously reached. In the fifth month, for example, the rate of
infant mortality was higher the longer the period of previous artificial
feeding. The tendency already noted in the entire group for the
rate to increase relatively to that for breast-fed infants immediately
following the beginning of artificial feeding at an early age was found
to be present also in this group of infants. Among the infants whose
exclusively artificial feeding commenced in the second month, for
example, a mortality prevailed in that month which was 1.9 times
that among breast-fed infants; the rate in the third month, however,
was 6.3 times, in the fourth 5.6 times, and in the fifth 6.9 times, the
corresponding rate for breast-fed infants. Among the infants whose
exclusively artificial feeding commenced in the third month, the
mortality in that month was 3.9 times, in the fourth month 5 times
and in the fifth 6.1 times, the corresponding mortality among breast
fed infants. In fact, the elimination of the group of premature and
plural babies and of infants whose mothers died within one year
after their birth appeared not to weaken but even to strengthen the
evidence that the type of feeding had a cumulative effect during the
early months of fife.

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TYPE OF FEEDING
T

75.— Monthly death rates, by duration o f previous artificial feeding; singleborn, full-term infants in eight cities whose mothers survived the first year after
confinem ent 1
■

able

Monthlydeath rates
of infants2—
Month
of life

First............
Second.........
Third..........
Fourth.........
Fifth...........
Sixth______
Seventh____
Eighth_____
Ninth..........
Tenth_____
Eleventh___
Twelfth

Exclu
sively
breast
fed

11.7
4.9
3.4
3.1
2.9
1.9
1.8
3.0
3.2
3.4
2.5
4.5

Monthly death rates of infants artificially fed from 2—

Exclu
Ninth
sively
First Second Third Fourth Fifth Sixth Seventh Eighth and
artifi month
month month month month month month month later
cially
fed
months
32.2
20.3
17.9
17.6
17.0
17.2
12.7
8.6
9.8
8.8
6.4
5.7

32.2
27.4
18.2
28.1
21.4
18.3
15.6
9.8
12.3
12.5
6.3
11.5

21.3
17.4
20.3
18.1
19.3
11.2
13.3
4.8
11.6
3.9

13.3
15.6
17.9
21.5
8.8
7.7
13.4
10.2
8.0
6.9

1.0
12.3
19.7
10.6
10.7
11.9
10.9
3.3
2.2

2.0
9.9
12.0
6.1
6.1
10.2
8.3
6.3

4.7
9.4
4.7
11.9
9.6
7.3
12.3

3.7
7.4
13.0
3.8

• 2.7
2.7
5.3
5.4

1.9
4.0
4.2

1 For basic figures see General Table 69, p. 216.
1 Omitting prematurely born infants, twins and triplets, and infants whose mothers died at or within
one year after confinement.

COLOR AND NATIONALITY OF MOTHER

The differences in the prevalence of breast and artificial feeding in
the several race and nationality groups are discussed in detail in the
next section. An answer to the question as to whether the mortality
in the group of artificially fed was raised unduly by the inclusion
within it of a disproportionate number of infants belonging to nation
alities which had high mortality rates is given in Table 76. The
table shows, in fact, that of the months lived from birth to the end
of the ninth a slightly smaller proportion (30.7 per cent) of the months
of artificial feeding than of those either of wholly or of partly breast
feeding (31.2 per cent and 34.2 per cent, respectively) were lived by
infants of nationality groups having higher than average mortality
rates. The proportion .was greatest in the case of the months lived
by infants while partly breast fed.
When allowance was made in Table 77 for the differences in prev
alence of artificial feeding in the several nationality groups, the ratio
of the mortality of the artificially-fed to that of the breast-fed infants
was slightly, but only very slightly, increased—from 3.9 to 4. The
correction for nationality, therefore, did not appreciably affect the
conclusion that artificial feeding was attended b y a much greater
mortality than breast feeding.
When a similar allowance was made in the case of partly breast
feeding, on the other hand, the ratio of the mortality of the partly
breast-fed to that of the breast-fed infants was slightly reduced from

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100
T

CAUSAL- FACTORS IN IN F A N T MORTALITY

76 .— Proportion o f months to the end o f the ninth lived by infants o f mothers
o f nationalities with high infant mortality rates, by type o f feeding; infants in
eight cities

able

M onths lived to end of ninth—
B y infants of m oth
ers of nationali
ties with high
infant mortality
rates 1

T yp e of feeding
Total

Number

Per. cent

Total___________________ _______ ________ ___________________ _____ 192,212. 5

60,754.0

31.6

110,384.0
33,904. 5
Artificial............ ........................................................ .............................. ............... 47,842.0
82.0

34.418.0
11.598.0
14,697. 5
40.5

31.2
34.2
30.7
49.4

1 Including French-Canadian, Polish, Portuguese, “ other foreign born,” and colored.
T

77 .— Mortality among partly breast-fed and exclusively artificially-fed as
compared with breast-fed infants, by color and nationality o f mother; infants in
eight cities

able

Deaths among infants—

Color and nationality of mother

Partly breast fed
Actual

Expected

Artificially fed

Ratio

Actual

Expected

Ratio

Total - ..................... ..............__

269

207.7

1.3

1,047

261.2

4.0

White................................— .......................

240

172.4

1.4

963

234.6

4.1

Native_____________________________
Foreign horn____________________ _
Italian._________ ______ ________
Jewish_________________________
French- C anadian_________ _____
German________________________
Polish__________________________
Portuguese_______ _____ ________
Other................................. .............

91
149
17
6
19
8
39
24
36

53.3
119.1
19.8
12.8
10.4
6.4
24.4
10.1
35.2

1.7
1.3
.9
.5
1.8
1.3
1.6
2.4
'1 .0

503
460
30
16
95
35
60
73
151

94.1
140.5
13.7
5.5
39.4
6.2
12.3
17.0
46.4

5.3
3.3
2.2
2.9
2.4
5.6
4.9
4.3
3.3

Colored____ _______ ______________ _____

35.3

26.6

3.2

The ratios between the mortality among artificially-fed and partly
breast-fed infants and that among breast-fed infants varied con
siderably from group to group. The mortality among artificially
fed was only 2.2 times that among breast fed in the Italian group, in
which both rates were relatively low; for the native white the ratio
was 5.3, and for the German it was 5.6.

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101

TYPE OF FEEDING

mortality than other babies, the excess in the mortality among them,
as will be shown later, was due in considerable part to the prevalence
of artificial feeding. So far as the mortality among the artificially fed,
as compared with that among the breast fed is concerned, therefore,
this disproportionate weighting of the group of artificially fed with
infants of mothers employed away from home could not have materi
ally affected the ratio.
T a b l e 78 .— Relative weighting o f type-of-feeding groups by infants in eight cities

whose mothers were employed away from home
Months lived to end of
ninth—

Type of feeding
Total

By infants whose
mothers were em
ployed away from
home
Number Per cent1

192,212.5

6,891.0

3.6

110,384.0
33,904.5
47,842. 0
82.0

977.5
2.360.0
3.540.0
13.5

0.9
7.0
7.4

1 Not shown where base is less than 100.

E A R N IN G S OP FA TH E R

The question whether the high mortality among the artificially
fed was in part a reflection of a disproportionate weighting of this
group with infants of fathers whose earnings were low— a group in
which mortality rates were higher than the average— is an important
one. The answer is given in Table 79, which shows that, on the
contrary, the group of artificially fed had the smallest proportion of
infants in the low-earnings group; i. e., in the group born m families
in which the fathers earned during the year following the birth less
than $650. Of the months lived from birth up to the end of the
ninth the proportion lived by infants in families in which the fathers’
earnings were under $650 was lowest (37.6 per cent) for the months
of artificial feeding, and highest (48.7 per cent) for the months of
partly breast feeding.
When allowance was made for this tendency, as in Table 80, the
relative mortality among artificially-fed, as compared with breast-fed
infants, was slightly increased. It has already been stated (p. 90)
that for the first nine months of life this ratio was 4.80; when the data
for one city for which earnings were not exactly comparable with the
others were omitted the ratio was raised to 5.17. When allowance
was made for the negative correlation between artificial feeding and
earnings, as in Table 80, the ratio of the rates was raised from 5.17
only to 5.24. The correction resulting from this correlation was thus
seen to be relatively slight.
The correction for the correlation between earnings and partly
breast feeding, on the other hand, worked in the opposite direction.
96515°— 25t------8

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102

CAUSAL FACTORS IN IN F A N T MORTALITY

When allowance was made for this corrélation, the ratio* of the
mortality among partly breast-fed to that among breast-fed infants
during the first nine months was reduced from 2.03 to 1.93.
T

7 9 .— Proportion o f months to the end o f the ninth lived by infants in fam ilies
in which the father earned less than $650, by type o f feeding; infants in seven
cities

able

Months lived from birth to
end of ninth— .
B y infants in fami
lies in which
father earned less
than $650

Type of feeding
Total

Number Per cent1
Total__________ ______ ___ ______ ____________________

180,412.0

Breast..__________ _______________ _____________________
Partly breast....................................................... ...............
Artificial......................................................... ................
Not reported.......................................... ............................. .........

75,364.5

41.8

102,768.5 42,683.5
31,412.0 15,287. 5
46,149. 5 17,362. 5
82.0
31.0

41.5
48.7
37.6

1Not shown where base is less than 100.
T

8 0 . — Mortality among artificially-fed and among partly breast-fed infants as
compared with that among exclusively breast-fed infants, by earnings o f father;
infants in seven cities

able

Deaths to end of ninth month among infants—
Earnings of father

Partly breast fed
Actual

Expected1

Artificially fed

Ratio

Actual

Expected1

Ratio

Total...................................................

186

96.5

1.9

829

158.1

5.2

Under $550....... ............................................
$550-$849............ .................................
$850-$l, 249.............. ...... ..............
$1, 250 and over............................ T..............
No earnings....... ................ .......................
Not reported.......... ..................................

81
64
20
7
8
6

39.2
34.0
13.0
3.2
3.1
4.1

2.1
1.9
1.5
2.2
2.6
1.5

315
313
118
32
32
19

49.8
62.6
26.5
7.8
5.2
6.3

6.3
5.0
4.5
4.1
6.1
3.0

1 Expected if rates that prevailed among breast-fed infants in the same months of life and in the same
earnings group had prevailed among partly breast-fed and artificially-fed infants.

The ratio of the mortality of artificially-fed infants to that of
breast-fed infants in each of the principal earnings groups is also
shown in Table 80. The ratio was much higher (6.3) for the group
with earnings under $550 than for that with earnings $1,250 and
over (4.1). This contrast between the ratios probably corresponds
to differences in the types of artificial feeding or to differences in the
care with which feeding was given in the various earnings groups.
V A R Y IN G PRE VALEN C E OF EAR LY ARTIFICIAL F E E D IN G

Reasons for the varying prevalence of early artificial feeding among
different groups of infants include those based upon the physical
condition of mother or child, those based upon inability of the mother
to nurse, and those based upon social customs. Probably a consider
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T Y P E OE F EE D IN G

103

able proportion of tbe prematurely born infants bad to be artificially
fed because they were too weak to nurse. This may have been the case
with many of the twins and triplets, of whom, also, a large proportion
may have been weaned because of the inability of their mothers to nurse
them. Among cases in which infants were reported to have been weaned
at an early age on account of the mothers* inability to nurse them it
was of course impossible to distinguish between those in which such
inability actually existed and those in which with proper care and
diet the mothers could have succeeded in nursing their babies. The
analysis of the varying prevalence of artificial feeding among the
babies of different orders included in this study suggested that the
first infants and those tenth and later in order may have been under
some special handicap in regard to the possibility of breast feeding,
owing either to their own physical condition or to their mothers’
inability to nurse them. The babies bom to older mothers appear
also to have been under a handicap (pp. 45 and 54-55).
The customs and traditions of nationality groups, as modified by
environmental influences, were undoubtedly the principal factor in
the variations in methods of feeding. The prevalence of artificial
feeding among the French-Canadian and of breast feeding among the
Jewish families can be accounted for only as a result of differences
in nationality customs. A campaign of education inculcating right
methods of feeding might, therefore, have reduced very materially
the prevalence of early artificial feeding and thereby reduced mate
rially the high infant mortality rates that characterized those groups
in which large proportions of infants were artificially fed.
Another important factor in the prevalence of artificial feeding
was the employment of the mother away from home. Such employ
ment usually required the mother to be absent from home for the
greater part of the day, and in a large proportion of these cases the
mothers did not attempt breast feeding for their babies after they
resumed work.
SUM M ARY

The artificial feeding of infants, when commenced in the early
months of life, was associated with a mortality between three and
four times that found to prevail among breast-fed infants. This
excess was not explained by the slight overweighting of the group of
artificially fed with twins and triplets, prematurely born infants,
and babies whose mothers died during the year, all of whom were
characterized by high rates. The excess appeared in all nationality
and earnings groups, though with variations depending upon particular
conditions. Early artificial feeding appeared to have been especially
hazardous. Furthermore, such feeding appeared to have resulted in
an increasing difference, for the first few months after it was begun,
between the mortality among the artificially-fed and that among the
breast-fed infants. Artificial feeding which commenced during the
last three or four months of the first year of life, however, seems not
to have been associated with any excess hazard, but on the contrary,
to have resulted in a slightly lower mortality than that prevailing
among infants breast fed during that period.

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COLOR AN D N A TIO N ALITY OF M O T H E R

In order that the influence of race and nationality upon their
mortality might be studied the infants in the eight cities were
classified according to their mothers’ race (whether colored or white)
and nativity, and those whose mothers were foreign born were
classified according to the mothers’ nationality (mother tongue).
The nationality of the mother was selected for tabulation instead of
that of the father on the ground not only that the infant’s vitality
depends in large part upon the mother’s health and condition during
pregnancy but also that the care received by the infant depends
upon the mother’s condition during his first year of life -and to some
extent upon the traditions and customs of the nationality to which
the mother belongs. In particular, the type of feeding is influenced
by the nationality traditions and customs as to maternal nursing.
Though the customs and traditions of the father’s nationality, also,
in the comparatively few cases in which it differed from that of the
mother,1 may also have influenced the child’s welfare, it is probable
that the influence of such factors is exerted principally through the
relation, if any, which nationality bears to earnings.
Nationality, it is evident, exerted its influence partly through
differences in physical vitality and partly through differences in type
of feeding, father’s earnings, and other environmental factors.
T a b l e 81 .— Infant mortality rates, by cause o f death and color and nationality o f

mother; live births in eight cities
Infant mortality rates from specified causes
Color and nationality of
mother

Total.......................

Live
births

Infant
deaths

All
causes

Gastric Respi
Epi
and in ratory
Early
demic
testinal diseases
infancy diseases
diseases

Other
causes

22,967

2,555

111.2

32.4

19.6

36.1

7.1

16.1

21, 510

2,330

108.3

32.6

17.9

35.1

6.4

16.4

Native____________ ____
Foreign born....................
Italian........................
Jewish_____ ________
French- Canadian__
German............... .
Polish....................
Portuguese.................
Other..........................
Not reported..............

12,102
9,408
1,426
1,233
1,074
776
1,266
669
2,962
2

1,135
1,195
148
66
184
80
199
134 .
384

93.8
127.0
103.8
53.5
171.3
103.1
157.2
200.3
129.6

25.2
42.2
21.7
10.5
64.2
27.1
64.0
101.6
38.5

13.0
24.2
27.3
8.9
25.1
18.0
33.2
50.8
20.6

36.1
33.7
33.7
22.7
44.7
30.9
38.7
20.9
35.8

5.4
7.7
7.7
4.9
6.5
11.6
3.9
14.9
8.1

14.1
19.2
13.3
6.5
30.7
15.5
17.4
12.0
26.7

Colored....................................

1,457

225

154.4

28.1

44.6

52.2

17.2

12.4

White...........................

The infant mortality rates for the different race and nationality
groups, which are given in Table 81, showed marked variations.
The rate for colored was decidedly higher than that for white inf ants154.4 as compared with 108.3. The group of infants of foreign-bom
1In one city for which a special tabulation of this point was made, 1,911 infants out of 2,197 (87 per cent)
had fathers and mothers of the same race and nationality group.

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COLOR AND NATIONALITY OF MOTHER

105

mothers had a considerably higher rate (127) than white babies
whose mothers were born in this country (93.8). Among the foreign
nationalities wide differences were found. The lowest rate was 53.5,
for infants of Jewish mothers— a markedly lower mortality than that
in the native white group. The highest rate (200.3) was found for
babies whose mothers were Portuguese. The infants of German
and Italian mothers had relatively low rates— 103.1 and 103.8,
respectively; and those of Polish and French-Canadian mothers had
relatively high rates— 157.2 and 171.3, respectively.
CAU SES OF D E A T H OF IN FA N T

The analysis by cause of death, also given in Table 81, showed that
with two or three exceptions the nationalities held about the same
relative rank in the mortality from each cause as in that from all
causes. The infants of Jewish mothers, for example, who had the
lowest rate from all causes, had much the lowest also from gastric
and intestinal and from respiratory diseases and next to the lowest
from causes peculiar to early infancy and from epidemic diseases.
In the native white group, which had next to the lowest rate from all
causes, the mortality was distinctly below the average from gastric
and intestinal diseases, from respiratory diseases, and from epidemic
diseases, and was equal to the average from causes peculiar to early
infancy. The infants of German mothers had rates below average
except from epidemic diseases. In the Italian group the mortality
was below average except from epidemic and from respiratory dis
eases; from gastric and intestinal diseases it was next to the lowest.
The infants of Polish and French-Canadian mothers had death rates
from gastric and intestinal diseases that were twice as high, and
those of Portuguese mothers a rate from these causes that was over
three times as nigh, as the average. In these three groups the mor
tality from respiratory diseases was markedly above the average;
their rates from other causes were also high, except that the Portu
guese had the lowest mortality of all from causes peculiar to early
infancy and the Polish the lowest of all from epidemic diseases.
N E O N A T A L M O R T A L IT Y

The death rates for the different nationalities during the first month
of life, given in Table 82, showed, with a single exception, variations
similar to those found in the mortality from causes peculiar.to early
infancy.2 The neonatal rate was lowest (28.4) for infants of Jewish
mothers, and the rate from causes peculiar to early infancy was lowest
for infants of Portuguese mothers. The Portuguese neonatal mor
tality rate, on the other hand, was 40.4— only slightly lower than the
general average, 44.8. Deaths during the first month among infants
of Portuguese mothers were charged m a large proportion of cases to
gastric and intestinal diseases; practically all those among infants
of Jewish mothers were charged to causes peculiar to early infancy.
This marked difference in the positions of the Jewish and Portuguese
-"groups, in relation to each other and to the general average, in respect
to neonatal mortality and to deaths from causes peculiar to early
J For rates in later months see General Table 70, p. 215.

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106

CAUSAL FACTORS IN IN FA N T MORTALITY

infancy suggests inaccuracies in reporting cause. On the other hand,
the peculiar customs of early infant feeding found among the Portu
guese, who frequently gave “ sopa,” a soup containing softened
crackers, to babies a few hours old, may perhaps account for the
occurrence in this group of a particularly large number of deaths
from gastric and intestinal diseases at ages under 1 month.
T

able

8 2 .—

Neonatal mortality rates, by color and nationality of mother; live births
in eight cities

Color and nationality of mother

Total._____________ ____ _________
White............ ......... .............................................
Native................................................... ...................
Foreign born____ _____ _____________ ____
Italian__________ _ ______________
Jewish_________ _____ ___________
French-Canadian........................................
German_____________ ________ _________
Polish_____________________ _________
Portuguese................. .............. ........................
Other_________________ __________
N ot reported.............. ......... ......... ............
C olored........... ................. ................. ................

Live
births

Deaths Neonatal
under 1 mortality
month
rates

. 22,967

1,028

44.8

21,510

934

43.4

12,102
9,408
1,426
1,233
1,074
776
1,266
669
2,962
2

502
432
66
35
58
33
66
27
147

41.5
45.9
46.3
28.4
54.0
42.5
52.1
40.4
49.6

1,457

64.5

PLURAL B IR T H S A N D P R E M A T U R IT Y

The prevalence of twins and triplets, according to Table 83, did
not vary significantly in the different nationality groups, with the
possible exception of the Jewish and the Portuguese. The Jewish
group had the highest proportion of twins and triplets (3 per cent)
and the Portuguese had the lowest (1.6 per cent); the average for
all nationalities was 2.3 per cent.
Table 84 shows that the prevalence of premature births, on the
other hand, varied markedly. Prematurity occurred more frequently
among infants born to native white than among those born to foreign
or to colored mothers. Among babies of Portuguese mothers the
proportion reported premature was especially low.
The influence of these variations in prevalence of premature births
in the different nationality groups upon the infant mortality rates
far these groups was relatively slight. The high proportion of births
to native white mothers which were premature tended to increase
both the rate from causes peculiar to early infancy and the neonatal
rate; but in spite of this high proportion of premature births the
neonatal mortality rate for infants of native white mothers was
below the average, the rate from causes peculiar to early infancy was
equal to the average, and that from all causes was markedly below
the average for the entire group.

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COLOR AND NATIONALITY OF MOTHER
T

8 3 .—

able

Proportion o f plural births, by color and nationality o f mother; live
births in eight cities
Live births
Plural births
Color and nationality of mother
Total

Colored............................................................... ..............................................

able

8 4 .—

Number

Per 1,000
live
births -23.0

22,967

529

21,510

496

23.1

12,102
9,408
1,426
1,233
1,074
776
1,266
'669
2,962
2

284
212
36
37
22
16
28
11
62

23.5
22.5
25.3
30.0
20.5
20.6
22.1
16.4
20.9

1,457

22.7

Proportion o f premature births, by color and nationality o f mother;
live births in eight cities
Live births
Premature births

Color and nationality of mother
Total

Number Per cent
22,967

1,158

White............................. ..................................... : ............................... ..........

21,510

1,076

5.0

French-Canadian.............. ..........................r________________ ___

12,102
9,408
1, 426
1,233
1,074
776
1,266
669
2,962
2

742
334
56
41
65
27
38
10
97

6.1
3.6
3.9
3.3
6.1
3.5
3.0
1.5
3.3

1,457

5.6

5.0

D EATH OF M O T H E R

In Table 85 the proportion of births to mothers who died at or
within one year after confinement is shown for the several nationali
ties. The proportion was low in the Jewish, Polish, and Italian
groups, high in the native white and the German, and highest in the
colored. However, the number of infants affected by the adverse
conditions following in the train of their mothers’ deaths was relatively
very small, and the influence of this factor in causing differences in
mortality rates in the several nationality groups therefore appeared
negligible. Thus in the colored group, in which the proportion of

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108

u sal

factors

in f a n t

m o r t a l it y

births to mothers who died was nearly twice that in the group with
foreign-born mothers, deaths of infants whose mothers died numbered
only seven; so that if the proportion of births to mothers who died had
been half as great as it was, the difference of three or four in the total
number of infant deaths in the group would have made but little
difference in the relative mortality rates for the infants of colored
and of foreign-born mothers.
T

8 5 . — Proportion o f births to mothers who died at or within one year after
confinement, by color and nationality o f mother; live births in eight cities

able

Live births-

Color and nationality of mother
Total

To mothers who
died at or within
one year after
confinement
Number Per 1,000

Total________________________________________________

22,967

140

6.1

White....... ..............................................................................................

21,510

129

6.0

12,102
9,408
1,426
1,233
1,074
776
1,266
'669
2,962
2

84
45
6
2
6
5
4
4
18

6. 9
4. 8
4. 2
1. 6
5. 6
6. 4
3. 2
6. 0
6.1

1,457

7.5

Native______ ___________________________________________________
Foreign born_______________________________________________ ____
Italian.______ ________ ________ _______ _________________ _
Jewish_____________ _____ ________ ______ _____
French-Canadian. _______ ___________________ ______ ________
German................................ ......................... .............................. .
Polish__________ _____________________________ ________
Portuguese____ ________ ____ ______ __________________ ____ ___
Other____ ________ _____ I ........................................................
Not reported......................................................................................
Colored_______ _______________ _______________ ______ ______

PLURAL B IR T H S , P R E M A T U R IT Y , A N D D E A T H O F M O T H E R

The three factors, plural birth, premature birth, and death of the
mother at or within one year after confinement, taken together, were
present in almost equal proportions of the cases in the different
nationality groups, as Table 86 shows. With the exception of the
Polish, Portuguese, and “ other foreign-born” groups, in which only
4.9, 3.3, and 5.6 per cent, respectively, of the infants were subjected
to the influence of one or another of these three factors, the differences
in these proportions among the several nationality groups were con
fined within a range of less than 2.5 per cent. The variations found,
moreover, tended toward an equalization of the death rates for the
different nationality groups. Thus the Portuguese, with the most
favorable proportion of births in these “ handicapped” groups, had
nevertheless the highest mortality; and the infants of native white
mothers, with the most unfavorable proportion of births in these
handicapped groups, had a mortality rate that was well below the
average.

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109

COLOR AND NATIONALITY OF MOTHER
T

8 6 .— Proportion o f plural or premature births or births to mothers who died
at or within one year after confinement, by color and nationality o f mother; live
births in eight cities

able

Live births
Plural or premature
births or births
to mothers who
died at or within
one year after
confinement

Color and nationality of mother
Total

Number Per cent
Total__________________________ ___________________ _
White........................................................................
N ative._____ ________ ________ ______ _____ j . ...........
Foreign born......................................................... ..............
Italian......................................... ......................
Jewish........ ......................... ...............
French-Canadian_____________________ ______ ________
German______________________ ____ .....................
Polish......... ...................................... .
Portuguese.............. ..................................................
O ther......... .................................. ...........
Not reported...................................................................
Colored________ ____ ________ ______

22,967

1,675

7.3

21,510

1,562

7.3

12,102
9,408
1,426
1,233
1,074
776
1,266
669
2,962
2

1,019
543
87
75
84
48
62
22
165

8.4
5.8
6.1
6.1
7.8
6.2
4.9
3.3
5.6

1,457

113

7.8

IN S T R U M E N T A L D ELIVE R Y

Instrumental delivery, as Table 87 shows, was more common among
native white mothers, 9.2 per cent of whom were thus delivered, than
among those of any other group.3 The lowest proportion of births
with instrumental delivery (3.1 per cent) was found for the Polish
mothers. These differences correspond fairly closely, as will be shown
later, to differences in economic status.
T

able

87 .— Instrumental delivery, by color and nationality o f mother; confinements

in Baltimore
Confinements
Instrumental
delivery

Color and nationality of mother
Total

Number Per cent
Total.

11,463

866

7.6

White.................

9,974

819

8.2

Native_____
Foreign bom.
Jewish—
Polish. . .
Ita lia n Other___

7,117
2,857
996
646
435
780

654
165
67
20
26
52

9.2
5.8
6.7
3.1
6.0
6.7

olored________

1,489

3.2

s These statements are based upon data for Baltimore only.

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110

CAUSAL FACTORS IN' IN F A N T MORTALITY
FR EQ U EN C Y OF B IR T H S

Age o f mother.

Among the different nationality groups comparatively slight differ
ences were found in the percentages of births to mothers of ages for
which the infant mortality rates were above average; namely, births
to mothers under 20 and to those 35 years of age ana over. According
to Table 88 the proportion of such births was highest for the German
(30.4 per cent) and lowest for the Polish group (19 per cent). With
the exception of the percentages for the German, French-Canadian,
and colored groups, the variations were confined within a range of
less than 5 per cent. One reason for the relatively slight differences
was the tendency for a low proportion of bitths to mothers imder 20
to be offset by a high proportion to those over 35, and for a high pro
portion to mothers under 20 to be offset by a low proportion to those
over 35 years of age.
These differences did not in all cases correspond with variations in
mortality. For example, the Polish and Portuguese groups, though
having high death rates, had low proportions of babies born to mothers
of these ages, and the German, though having a relatively low death
rate, had the highest proportion of babies born to such mothers. On
the other hand, the mortality among the Jewish infants tended to be
lessened by a low percentage, and that among the French-Canadian
infants tended to be raised by a high percentage, of babies whose
mothers belonged to age divisions which had high death rates.
T a b l e 8 8 . — Proportion of births to mothers under 20 and to those 85 years o f age and

over, by color and nationality o f mother; live births in eight cities 1
Live births-

Color and nationality of mother
Total

To mothers under
20 and 35 years of
age and over
Number Per cent

Total_________

22,967

6,230

22.8

White................................

21,510

4,848

22.5

Native........................
Foreign horn......... .
Italian.---- -------Jewish...... ...........
French-Canadian.
German________
P o lish ................
Portuguese......... .
Other---------------Not reported____

12,102
9,408
1,426
1,233
1,074
776
1,266
669
2,962
2

2,658
2,190
337
250
313
236
241
147
666

22.0
23.3
23.6
20.3
29.1
30.4
19.0
22.0
22.5

Colored.............................

1,457

382

26.2

1 For basic figures see General Table 23, p. 195.

Order o f birth.

Table 89 gives the prevalence of births of orders for which the
mortality rates were above average, by nationality of the mother^
The proportions of infants of the fifth and later orders— those for
which the rates were above average—ranged from 19 per cent for
babies of native white mothers to 42.6 per cent for those of FrenchCanadian mothers. The percentages for the foreign-bom groups had

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COLOR AND NATIONALITY OF MOTHER

111

a much narrower range—from 28.3 for the “ other foreign-born” to
42.6 per cent for the French-Canadian group.
When allowance was made in Table 90 for this variation in the
proportions of births of various orders, however, little change was
made m the relative mortality b y nationality. The mortality of
babies of French-Canadian mothers was diminished slightly and that
of babies of native white mothers raised slightly relatively to the
rates m other groups.
T

able

Proportion o f births fifth and later in order, by color and nationality
o f mother; live births in eight cities 1

89.

Live births—
Fifth and later in
order

Color and nationality of mother
Total

Number Per cent
Total...................
White_______
Native.........._
Foreign born__
Italian............
Jewish............
Freneh-Canadian____
German_____
Polish_______
Portuguese....... .........
Other_____
Not reported....................
Colored................

22,967

5,974

26.0

21, 510

5,462

25.4

12,102
9,408
1,426
1,233
1,074
776
1,266
669
2,962
2

2,294
3,168
540
406
457
255
440
231
839

19.0
33.7
37.9
32.9
42.6
32.9
34.8
34.5
28.3

1,457

512

35.1

1 For basic figures see General Table 31, p. 198.
T

able

9 0 .—

Relative mortality, by color and nationality o f mother, when influence
o f order o f birth is eliminated; live births in eight cities
Infant deaths
Color and nationality of mother
Actual

Ratio of
Expected1 actual to
expected
(per cent)

Total........................

100.0

W h ite..._______
Native.................
Foreign born_____
Italian........
Jewish___________
Freneh-Canadian______
German........ ........
Polish__________
Portuguese......... ..............
O th e r .......... ...................
Not reported........................
Colored.................. ..................

97.6
f OHt* k
1,195
148

164.4

184

86.4
90.0
47.5
142.3

0.2
225

1 Expected at average rates by order of birth, irrespective of mother’s nationality.

Interval since preceding birth.

Except for the very low percentage for the Jewish group (16.4)
comparatively little variation in the proportion of births following

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112

CAUSAL FACTORS IN IN F A N T MORTALITY

preceding births at short intervals was found for the several nation
alities.4 According to Table 91 the highest proportion (33.5 per cent)
was in the colored group and the lowest (23.6 per cent) in the Ger
man except for the very low figure of 16.4 per cent in the Jewish.
Table 92 shows how the positions of the different nationalities were
affected when allowance was made for the variations in the propor
tion of short-interval births. It is noteworthy that the mortality of
Jewish infants still appears very favorable as compared with other
nationalities even after due account is taken of the unusually low
proportion of infants born at short intervals after preceding births.
T

able

9 1 .—

Proportion o f short-interval births,1 by color and nationality o f mother;
live births in Baltimore second and later in order 2
Live births second and later
in order—
Following preced
ing births at short
intervals1

Color and nationality of mother
Total

Number Percent3
Total________________________________________
White_________ ____ _______________________
Native___ ______ ___________ _______ ____
Foreign born.............................................................
Italian.................................... .................
Jewish.......... ......................................................
Germ an............................... .......................
Polish....... ................. ......... .........
Other............................................................
Colored.............................................................

7,929

2,072

26.1

6,855

1,712

25.0

4,606
2,249
356
793
259
515
326

1,174
538
111
130
61
146
90

25.5
23.9
31.2
16.4
23.6
28.3
27.6

1,074

360

33.5

1 For definition of interval see p. 60.
2 For basic figures see General Table 37, p. 200.
8Not shown where base is less than 100.
T

9 2 .— Relative mortality, by color and nationality of mother, when influence
of interval since preceding birth is eliminated; live births in Baltimore second and
later in order

able

Infant deaths
Color and nationality of mother
Actual

Ex
pected «

Ratio of
actual to
expected
(per cent)
100.0

Total___

845

844.6

White____________

675

725.3

93.1

Native...........
Foreign born..
Italian____
Jewish____
German.
Polish....... .
Other........

465
210
31
34
24
82
39

488.2
237.1
39.3
79.6
27.1
56.1
35.0

95.2
88.6
78.9
42.7
88.6
146.2

170

119.3

142.5

Colored.

llp-‘

° Expected at average rates by interval for second and later births irrespective of nationality of mother.
4 The data on interval were limited to Baltimore. For definition of short interval see p. 60.

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113

COLOR AND NATIONALITY OF MOTHER

Interval before succeeding pregnancy.

According to Table 93, the proportion of births to mothers who
became pregnant during the infant’s first year of life varied from 7.9
per cent in the Jewish to 25.2 per cent in the Italian group. These
percentages, however, tend to overstate the importance of this factor,
since the proportions of the time lived by infants after their mothers
had become pregnant to the total time lived by all infants were much
smaller (p. 68). Though the differences were not large enough to
account for a n y great variation in the mortality rates in the several
groups, the Jewish infants again seem to have had the most favorable
conditions.
T

93 .^ P rop ortion o f births to mothers who became pregnant before end o f first
year o f infant’s life, by color and nationality o f mother; live births in Baltimore

able

Live births—
To mothers who
became pregnant
during first year
of infant’s life1

Color and nationality of mother
Total

Number
Total__________________________________________________
White_________________________________________________ ___________
Native____ ______ ________________________________________
Foreign born______________________ ____ _________________ ______
Jewish________ _______ _________________________ ________
Polish..________ _______ _____________________ ________
Italian................................ ..............................................................
Other.....................................................................«_____ ____ ____
Colored____ ________ _____ ____ _____ __________________ _______

Per cent

10,797

1,232

11.4

9,492

1,037

10.9

6,739
2,763
961
625
412
755

662
375
76
106
104
89

9.8
13.6
7.9
17.0
25.2
11.8

1, 305

195

14? 9

i Omitting cases in which infant died in m onth in which mother became pregnant.

TYPE OF FEEDING

Marked differences were found in the customs of the differeiit
nationality groups in respect to types of feeding. Of the months
lived from birth to the end of the mnth the infants of Italian mothers
had the largest proportion— 68.6 per cent— of months of exclusively
breast feeding. They were followed closely by the infants of Polish
mothers with 65.9 per cent and by those of Jewish mothers with
61.5 per cent. The lowest proportion (42.7 per cent) was that of the
French-Canadian group. (See General Tables 71 and 72, p. 216.)
The greatest prevalence of artificial feeding, on the other hand,
was found, according to Table 94, in the French-Canadian group;
the infants of French-speaking mothers born in Canada were fed
artificially during 44 per cent of the months which they lived from
birth to the end of the ninth. The Portuguese group came next
with 31.9 per cent, followed by the native white with 28.3 per cent.
The lowest proportions were those of the infants of Jewish and of
olish mothers— 11.3 and 11.1 per cent, respectively.
Since the practice of artificial feeding was fraught with greatly
increased hazards to the infants, these differences in the prevalence
of breast and of artificial feeding in the several nationality groups
were important in explaining differences in their mortality rates.

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CAUSAL FACTORS IN IN F A N T MORTALITY

T able 94 — Prevalence of artificial feeding, by color and nationality; o f mother
infants in eight cities
Months lived to end of ninth
M onths o f artificial
feeding

Color and nationality of mother

Total
N um ber

Per cent1

Total.

192,212.5

47,842.0

24.9

W h ite ..,_______________

180,397. 5

45,516. 5

25.2

Native_____________
Foreign bom _______
Italian___________
Jewish..................
French-Canadian.
German________
Polish...................
Portuguese...........
Other....................
Not reported........

102,285. 5
78.112.0
11,943. 0
10. 688.0
8, 666.0
6, 524.0
10,391. 5
5,410.0
24,471.5
18.0

28,962.0
16,554. 5
1.563.0
1.207.0
3,813. 5
1,405. 5
1,155. 5
1,725. 5
5,677. 5
7.0

28.3
21.1
13.1
11.3
44.0
21.5
11.1
31.9
23.2

11,815.0

2,325. 5

19.7

Colored.

1 Not shown where base is less than 100.

With one or two exceptions variations in the prevalence of artificial
feeding corresponded to variations in these rates. Among the
noteworthy exceptions must be mentioned the practically equal pre
valence of artificial and of breast feeding in the Jewish and Polish
groups. In each of these groups the proportion of months lived from
birth to the end of the ninth during which the infants were wholly
breast fed was between three-fifths and two-thirds; and the pro
portion during which they were fed artificially was approximately
one-ninth; yet the mortality rate for the Jewish, which was lower
than that for any other race or nationality, was only one-third of
the rate that prevailed in the Polish group. The mortality from
gastric and intestinal diseases among Polish infants was six times as
high as that among Jewish. Evidently, in spite of the similarity in
prevalence of the several types of feeding, other factors— differences
perhaps in the quality of artificial food, perhaps in social and eco
nomic environment, perhaps in physical vitality— must have been
concerned in the causation of these marked variations in the rates.
An analysis of the mortality in the several nationality groups, as
modified by allowance for variations in the prevalence of breast and
artificial feeding, is presented in Table 95. The most favorable
showing was made by the Jewish group, which maintained the same
position after this allowance as before. The infants of native white
mothers had the next most favorable rate; in this case, though the
giving of artificial food was more prevalent than in any other group
except the French-Canadian and the Portuguese, the mortality
among both the breast fed and the artificially fed was low as com
pared with that among the breast-fed and the artificially-fed infants
of most of the other nationalities. The German group ranked more
favorably than the Italian, though their rates were practically
identical when no allowance was made for differences in feeding; in
other words, in the Italian group a less favorable mortality ex-

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115

COLOR AND NATIONALITY OF MOTHER

perience associated with other factors was offset by a greater practice
of breast feeding. The relative rank of the infants of Polish, FrenchCanadian, and Portuguese mothers was altered when allowance was
made for variations in the prevalence of breast and artificial feeding;
the mortality in the French-Canadian group was changed to the
lowest position, and that in the other two groups was approximately
the same, the Polish being slightly higher. The markedly greater
prevalence of breast feeding among the infants of Polish mothers
tended to offset a mortality otherwise relatively very unfavorable,
and, therefore, when no allowance was made for variations in the pre
valence of breast and artificial feeding their rate appeared lower than
that for either of the other two groups.
T

9 5 . — Relative infant mortality, by color and nationality o f mother, when
influence o f differences in type o f feeding is eliminated; infants in eight cities

able

Infant deaths
Color and nationality of mother
Actual

White_________ ______ ________ - ................................................................

Italian........................ ........... ............................................ ................
Jewish........................................... .....................................................
German.................................._•________________________________

Ratio o f '
Ex
actual to
pected 1 expected
(per cent)

2,555

2,555. 0

2,330

2,404. 3

96.9

1,135
1,195
' 148
66
184
80
199
134
384

1,403. 6
1,000.7
134. 7
118.8
143. 9
84.9
117.4
80. 5
320.3
.2

80.9
119.4
109. 9
55.6
127.9
94.2
169. 5
166.5
119.9

225

150.7

149.3

100.0

1 Found by applying average mortality rate for each month of life and type of feeding to groups of infants
classified by month of life, type of feeding, and color and nationality of mother; in case of infants not fed, by
applying average mortality rate among infants not fed to infants in each color and nationality group.

For infants not fed the variations in the different nationality
groups were less marked. Nevertheless in this group the rate of the
infants of Jewish mothers was one-third below, and that of the
infants of French-Canadian mothers was one-third above, the average.
The babies of Portuguese and German mothers had relatively low
rates, and the colored babies had the next to the highest rate. The
most notable difference between rank as to mortality of all infants
and rank as to mortality of infants not fed appeared in the case of
the Portuguese group, which was transferred from the place next to
the highest to that next to the lowest. The peculiar customs of
infant feeding found among the Portuguese of the study were probably
responsible for this change in position. (See General Table 74, p. 220.)
When the infants who died not fed were disregarded, the lowest
mortality was found in the Jewish and the highest in the Polish
•up, the relative rank being the same as that shown in Table 95.5
5 Further evidence upon the relative mortality among breast-fed, partly breast-fed, and artificially-fed
infants in the several nationality groups is contained in General Table 74, p. 220.

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116

CAUSAL FACTORS IN IN F A N T MORTALITY

It is clear that though differences in prevalence of breast and arti
ficial feeding had a decided influence upon the rates for the several
nationality groups, marked differences in mortality still remained to
be accounted for by other factors.
HOUSING

CONGESTION

The variations in the proportions of infants in families living one
or more persons per room are shown in Table 96. The native white
group had the smallest percentage living in such homes and the
Polish the largest; 32.8 per cent of the babies in the former as com
pared with two -and one-half times as large a percentage (82.5) of
these in the latter were in families living one or more persons per
room. Next to the native white in percentage living in such homes
came the German with 50.9 per cent and the colored with 54 per
cent. The Italian group had next to the highest percentage, 75.7.
When allowance was made in Table 97 for the variations in housing
congestion, the rank of the several nationality groups as to infant
mortality was not materially altered. The Jewish group still had a
remarkably low and the Portuguese an excessively high infant mor
tality; the figure for the Polish babies seemed somewhat reduced.
T

9 6 . — Proportion o f infants in fam ilies living one or more persons per room,
by color and nationality o f mother; infants in seven cities who survived two weeks 1

able

Infants who survived two
weeks—
Color and nationality of mother
Total

In families living
one or more per
sons per room
Number Per cent

Total_______________________________
White.................................................
Native_________________ ________
Foreign born........................................
Italian________ _______ ______
Jewish______________ _____
French- C anadian_____ _______
German_____________ ____
Polish________ _____
Portuguese...........................
Other___________
Not reported........................
Colored______________ .

20,698

9,730

47.0

19,337

8,995

46.,5

10,896
8,441
1,303
1,186
1,026
707
1,119
652
2,446
2

3,578
5,417
987
695
606
360
923
461
1,384
1

32.8
64.2
75.7
58.6
59.1
50.9
82.5
70.7
56.6

1,361

735

54.0

1 Excluding a small num ber of infants in Baltimore who had not lived tw o weeks in dwelling to which
data as to congestion related. For basic figures see General Table 75, p. 221.

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COLOR AND NATIONALITY OF MOTHER
T

±IY

97.
Relative mortality, by color and nationality o f mother, when influence of
housing congestion is eliminated; infants in seven cities who survived two weeks 1

able

Infant deaths
Color and nationality of mother
Actual

Total______
White.
Native_____________
Foreign born________
Italian..... ...........
Jewish..................
French-Canadian.
German_________
Polish...................
Portuguese-....... .
Other___________
Not reported.....
Colored.

Ratio of
Ex
actual to
pected 8 expected
(per cent)

1,566

1,565.7

1,429

1,459.8

97.9

660
769
84
32
136
53
138
117
209

734.0
725.8
119.2
95.0
82.4
54.3
119.5
58.6
196.6
.2

89.9
106.0
70.5
33.7
165.0
97.6
115.5
199.7
106.3

137

105.9

129.4

100.0

EMPLOYMENT OF MOTHER DURING PREGNANCY

Variations among the several nationalities in the prevalence of
employment of mothers away from home during pregnancv are
shown in Table 98. The proportions of infants born to mothers
thus employed varied from 2.1 per cent in the Jewish to 41 5 per
cent in the colored group. It is noteworthy that the figures were
low lor the Jewish, Italian, native white, and German groups for
winch the mortality rates were below average, and high for'th e
Trench-Canadian, Polish, Portuguese, and colored groups, for which
the mortality rates were markedly above average. When allowance
was made, however, for these variations, as in Table 99, the relative
mortality m the several nationalities was not materially altered,
l he ml ants of the Jewish group showed the lowest mortality whether
then* mothers were employed, or not employed, and those of the
Canadian, Polish, Portuguese, and colored groups— both
those whose mothers were employed and those whose mothers were
not employed— showed high rates as compared with infants of
mothers of other nationalities.
9 6 5 1 5 ° — 2 5 t -------9

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118
T

CAUSAL FACTORS IN IN F A N T MORTALITY

able

9 8 .—

Employment o f mother away from home during pregnancy, by color
and nationality o f mother; live births in eight cities
Live births—

Color and nationality of mother
Total

To mothers em
ployed
away
from home dur
ing pregnancy
Number

Total

............... ............ ................ .........

Whit.fi

..................................

German_____________ _____ ___________ ______________________
Polish________________ ________________ ______ ______ _________
Other______ ______ ___________________________ ________ ______
Not reported_______________________________________ ____ ____

Per cent

22,967

3,084

13.4

21, 510

2,480

11.5

12,102
9,408
1,426
1,233
1,074
776
1,266
669
2,962
2

862
1,618
70
26
292
99
437
260
434

7.1
17.2
4.9
2.1
27.2
12.8
34.5
38.9
14.7

1,457

604

41.5

9 9 . — Relative mortality, by color and nationality o f mother, when influence
o f employment o f mother during pregnancy is eliminated; live births in eight
cities

able

Infant deaths
Color and nationality of mother
Actual

Total ............................................... .

Expected 1

Ratio of
actual to
expected
(per cent)

2,555

2,555. 0

100.0

W hite...............................................................................................................

2,330

2,359.1

98.8

N ative_____________________i___________________________________
Foreign born _____________ __________
Italian_________ ______. ______ _________
Jewish_______________ __________
French-Canadian_____ _____________
German. ................................
Polish__________ ____
Portuguese. ______________
Other
........................
N ot r e p o r t e d .........................

1,135
1,195
148
66
184
80
199
134
384

1,272.8
1,086. 2
153. 5
128. 2
130. 2
85. 6
163. 7
87.6
337.3
.2

89.2
110.0
96.4
51.5
141.3
93.5
121.6
153.0
113.9

225

195.9

114.8

C olored. _____ __________________________

...

•

1 Expected at average rates for infants of mothers in the corresponding employment-during-pregnancy
groups, irrespective of nationality.

The question is important whether the variations in the propor
tions *oi mothers employed were due chiefly to differences in the
economic status of the families or were also influenced by nationality
traditions and customs as to the employment of mothers. According
to Table 100, in which allowance was made for the variations in
father’s earnings in the several nationality groups, nationality frsfc*
ditions and customs exerted a marked influence in this respect. O
the Jewish and the Italian mothers very few went out to work: in the

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119

COLOB AND NATIONALITY OP MOTHEB

former group only one-seventh, and in the latter one-fourth, as many
mothers were employed away from home as were so employed on the
average in the corresponding eamings-of-father groups. On the
other hand, of the French-Canadian mothers nearly twice, and of the
colored, the Portuguese, and the Polish over one and three-fourths
times, as many were employed away from home as were so employed
on the average in the corresponding earnings-of-father groups. So
far, therefore, as the mother’s employment was dependent upon the
customs and traditions of the nationality group, these customs and
traditions associated with nationality were responsible for the exces
sive mortality in certain groups and for the very favorable mortality
in other groups associated with the greater or less prevalence of
mother’s employment.
T able 100 .— Prevalence o f mother’s employment away from home during pregnancy,
by color and nationality o f mother, when influence o f economic need as a factor in
mother’s employment is eliminated; 1 live births in seven cities
Live births to mothers employed
away from home during pregnancy
Color and nationality of mother
Actual

Total________________________________________
White____________________________
Native _. ____________ _____________ ...
Foreign born______________ ______
Italian—......... ........................... .........
Jewish__________________ ____
French- Canadian_______ _______
German_________________
Polish____ __________
Portuguese______________
Other
- ___________
Not reported_________ ____ _ _
C olored.... .......................................

Expected 2

Ratio of
actual to
expected
(per cent)

3y071

3,070. 7

100.0

2,467

2,738. 5

90.1

856
1,611
68
26
292
99
436
260
430

1,252. 6
1,485.9
270.8
181.9
155.1
101.9
247.8
145.5
382.8
.1

68.3
108.4
25.1
14.3
188.3
97.2
175.9
178.7
112.3

604

332.2

181.8

1 A s measured b y the am ount of father’s earnings during year after birth of infant.
2 Expeeted if the proportion of mothers em ployed away from home during pregnancy in each earningsof-father group were applied to the live births classified b y nationality of mother and earnings of father.

E M P L O Y M E N T O F M O T H E R D U R IN G FIRST YEA R O F IN F A N T ’ S LIFE

The variations in the proportion of mothers employed away from
home during the first year of the infant’s life, as shown in Table 101,
appeared to follow closely those found in the prevalence of such
employment during pregnancy. The lowest proportion (1.1 per
cent) was found in the Jewish group and the highest (30.2 per cent)
in the colored. Among the French-Canadian, Polish, and Portu
guese mothers employment during this period was especially
prevalent.
Since even in the group in which the employment of mothers
away from home during the first year of the infant’s life was most
eemmon— the colored— the proportion of mothers so employed
was less than one-third and since the months lived by infants while
their mothers were employed constituted a still smaller proportion

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CAUSAL FACTORS IN IN FA N T MORTALITY

of the total months lived by all infants of the same group, the in
fluence of these variations in the prevalence of mother’s employment
was not such as to change materially the relative rank in mortality
rates of the several nationalities.
The more frequent employment away from the home of mothers
in the Portuguese and French-Canadian groups may have been
responsible in part for the greater prevalence of artificial feeding
in these groups.6 On the other hand, the unusually high proportion
of Polish mothers who were so employed was associated with a
record as to artificial feeding that was practically as favorable as
that of the Jewish group.
In Table 102 the influence of nationality traditions and customs,
as distinguished from that of low income, over the prevalence of
employment of the mothers during the first year of their infants’
lives is shown. Such employment appeared to be relatively rare
among the Italian and Jewisn mothers, but in the colored and the
French-Canadian group twice as large a proportion of mothers were
so employed as the average for all mothers whose husbands earned
corresponding incomes.
T able 101 .— Prevalence o f mother’s employment away from home during first year
o f infant’ s life, by color and nationality o f mother; infants in seven cities
Live births—

Color and nationality of mother
Total

To mothers
employed away
from home dur
ing first year of
infant’s life
Number Per cent

White____________________________ ______ _____

___________________

Native_______________________________ __________________________
Foreign born____ ____ ____ __________ ______ _____ _______________
Italian_______ _______ __ ________________ _________ _________
Jewish..._______________________ ____ _____________ _____ ____
French-Canadian____________ _____ ________ ______ ______ _____
German_____________ : ________________ _________ __________
Polish____________________________ ____ _________ ______
Portuguese___ _______________ _______ _____ ______ ______ _____
Other________________________ _____________ ____________. . . .
Not reported_______________ _____ _____ ____ ________________

21,536

1,730

20,085

1,292

8.0
6.4

11,323
8,762
1,355
1,223
1,074
729
1,167
669
2,543
2

448
844
25
13
173
41
265
171
156

4.0
9.6
1.8
1.1
16.1
5.6
22.7
25.6
6.1

1,451

438

30.2

6 See pp. 142-143 for the influence of m other’s employm ent away from home upon the prevalence of
artificial feeding.

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COLOR AND- NATIONALITY OP MOTHER

¡Prevalence o f mother's employment away from home during first year
o f in fa n ts life, by color and nationality o f mother, with influence o f father's earn
ings as a factor in mother's employment eliminated; infants in seven cities

T a ®l.e

Live births to mothers employed
away from home during first year
of infant’s life

Color and nationality of mother
Actual

Total.
White.
Native_____________
Foreign bom ________
Italian..... .............
Jewish__________
French-Canadian.
German_____ ___
Polish._________
Portuguese______
Other___________
Not reported. . . . .
Colored.

Expected1

Ratio of
actual to
expected
(per cent)

1,730

1,729.3

100.0

1,292

1,510.0

85.6

448
844
25
13
173
41
265
171
156

640.3
869.7
166.7
107.2
82.4
54.8
153.7
91.0
213.8
.l

70.0
97.0
15.0
12.1
210.1
74.8
172.4
187.8
73.0

438

219.3

199.7

jiApeobeu ii ine proportion or mptners employed away from home during the first vear of the infant’ s
life in each earnings-of-father group tfefeapplied t o M v e l l & l c t o W b y

EARNINGS OF FATHER

Among the most important differences that characterized the
various nationalities were those in economic status as indicated by
the father’s earnings. This point is brought out clearly in Table
103, which gives for each nationality, as indicated by the native
language of the mothers, the proportion of births that occurred in
families in which the father earned less than $650. The proportion
was highest in the colored group, in which 81.9 per cent of the births
occurred m families in which the father earned less than $650. The
lowest proportion (27.4 per cent) was found in the native white
group. Marked differences appeared among the different foreignbom nationalities. Of these the German group had the lowest
proportion, 41.2 per cent, of births in families in which the father
earned less than $650, followed closely b y the French-Canadian with
43.2 per cent and the Jewish with 44.5 per cent. The Italians, the
Polish, and the Portuguese all had markedly high proportions in
this earnings group— 70.5, 78.3, and 78.5 per cent, respectively.
These differences in earnings ran parallel with and corresponded
closely to differences in the infant mortality rates.
When allowances were made in Table 104 for variations in father’s
earnings among the nationality groups, the differences in the death
rates appeared much reduced. The high mortality among the
colored, for example, seemed to have been largely a reflection of
their low economic status. Among the Polish, too, low father’s
ejmings appeared to have accounted in large part for the excessive
eath rate. In the Portuguese and French-Canadian groups, on
the other hand, a mortality considerably above the average appeared
not to be accounted for b y any differences in father’s earnings.
The low mortality among the infants of native white mothers seemed

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122

CAUSAL FACTORS IN IN FAN T MORTALITY

to have been due in part to their comparatively superior economic
position. When the effects of this superiority were eliminated,
indeed, the Italian group appeared to have had lower rates than
the native white, and the Jewish group showed the lowest rates of all.
T

able

1 0 3 .—

Proportion o f births in fam ilies in which the father earned less than
$650, by color and nationality o f mother; live births in seven cities 1
L ive births—
In families in which
father earned less
than $650

C olor and nationality of mother
T otal

Num ber
....................................

Per cent

..............................

21,536

9,133

42.4

W hite ________ _________________________________________________________

20,085

7,944

39.6

11,323
8,762
1,355
1,223
1,074
729
1,167
669
2,543
2

3,097
4,847
955
544 .
464
300
914
525
1,145

27.4
55.3
70.5
44.5
43.2
41.2
78.3
78.5
45.0

1,189

81.9

Total

Native
___________________________________________________________
Foreign born ___________________________________________ __________
Italian.
______________________________________________________
Jewish________________________ _____ ______________ _____________
French-Canadian......... ........................ ....................................... ........
German............................ ............................ ................... ...........................
P olish ._____ ________________ ________________ __________________
Portuguese ______________________ . . . . __________________ ______ _
Other! . _____ ________ ______________! ____ . . . . _______________
N ot reported....

Colored.........

1,451

1 For basic figures see General Table 76, p. 221.
T

able

1 0 4 .—

Relative mortality, by color and nationality o f mother, when influence
of father’s earnings is eliminated* live births in seven cities
Infant deaths
Color and nationality of mother
Actual

Total.
White.
Native...... ..................
Foreign born.... .........
Italian__________
Jewish_____ ____
French-Canadian.
German________
P olish .................
Portuguese______
Other................. .
Colored.

Expected1

Ratio of
actual to
expected
(per cent)

2,368

2,367.8

100.0

2,147

2,163.8

99.2

1,063
1,084
135
66
184
74
185
134
306

1,115.6
1,048. 2
176.3
137.3
118.8
79.8
156.6
91.2
288.1

95.3
103.4
76.6
48.1
154.9
92.7
118.1
146.9
106.2

221

204.0

108.4

i
Expected at average rates prevailing in each earnings-of-father group, irrespective of nationality of
mother.

When allowances were made for variations in economic status
measured b y per capita income from father’s earnings, among the
several nationality groups, as in Table 105, almost the same results
were obtained as when allowances were made for variations in father’s

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123

COLOR AND NATIONALITY OF MOTHER

earnings regardless of the size of families. (See General Tablé 77,
p. 222.) The reason for this, presumably, was that, on the average,
differences in per capita income corresponded very closely with dif
ferences in father’s earnings (p. 149). It may be noted, however,
that in this table the relative positions of the Portuguese and FrenchCanadian groups were reversed, the mortality among the Portuguese
appearing slightly higher.
T a b l e 105.— Relative mortality, by color and nationality o f mother, when influence of

differences in economic need 1 is eliminated; live births in seven cities
Infant deaths

Color and nationality of mother
Actual

Total..............
White................... .
Native____________
Foreign born_______
Italian__ .1.........
Jewish_________
French-Canadian.
German...............
Polish............ .
Portuguese_____
Other__________
Colored_______ _______

Ratio of
Ex
actual to
pected 8 expected
(per cent)

2,368

2,367. 2

100.0

2,147

2,181.4

98.4

1,063
1,084
135
66
184
. 74
185
134
306

1,147. 2
1,034. 2
168.6
138.8
127.2
82.2
145.2
86.2
286.0

92.7
104.8
80.1
47.6
144.7
90.0
127.4
155.5
107.0

221

185.8

118.9

1As measured by per capita income from father’s earnings.
. 8Expected if the rates prevailing in each per capita income (from father’s earnings) group had prevailed
m the corresponding group for each nationality.

E A R N IN G S OF F A T H E R A N D T Y P E O F FEE D IN G

The two factors, earnings of father and type of feeding,
appeared to have exerted an important influence in produc
ing the differences in the mortality rates for the several nationali
ties. Since, as will be shown later (p. 155), there was comparatively
little correlation between father’s earnings and the prevalence of
artificial feeding, the combination of these two factors may have
accounted for the differences in the rates for certain of the nationali
ties. Thus the mortality among the infants of Italian mothers, which
was slightly below the average for the entire group, was influenced by
two marked causes— an unusual prevalence o f exclusively breast
feeding and an unusually low economic status. When allowance
was made for the former only, the rate appeared to be excessive,
because of the influence of low economic status; when allowance was
made for the latter only, the rate appeared to be unusually favorable,
because of the influence of the favorable feeding.* But when allow
ances were made for both factors together, as in Table 106, the rate
for the Italian babies did not appear to vary in any marked degree
from that for the native white group.

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T

CAUSAL FACTORS IK IN F A N T MORTALITY

1 0 6 . — Relative mortality, by color and nationality o f mother, when influence
o f earnings o f father and type o f feeding is eliminated; infants in seven cities

able

Infant deaths1
Color and nationality of mother
Actual

White ...................................................................................................-

Ratio of
to
Expected 1 actual
expected
(per cent)

1, 582

1,581.7

100.0

1,425

1,449.1

98.3

675
750
84
36
134
51
128
106
211

762.9
686. 2
96.8
73.0
105.0
52.6
85.6
75.1
198.1

88.5
109.3
86.8
49.3
127.6
97.0
149.5
141.1
106.5

157

132.6

118.4

1 During first nine months only. Excluding 514 not fed who died at once and 6 for whom type of feeding
was not reported.
8 Expected at average rates for each type of feeding in each month in each earnings group, irrespective
of color and nationality.

SUM M ARY

The analysis has shown clearly that color and nationality exerted
a powerful influence over infant mortality, though whether that influ
ence was due wholly to customs and traditions or partly to differ
ences in innate vitality could not be determined. The marked varia
tions in type of feeding among the various nationalities and the differ
ences in average father’s earnings, in proportions of mothers employed
away from home, and in degrees of congestion in living quarters were
responsible in large measure for the differences in the infant mortality
rates. But even after each of these factors was allowed for, the
babies of certain nationalities, notably the Jewish, were found to
have experienced very low mortality, while those of other nationali
ties, notably the Polish and the Portuguese, had high rates. Though
no attempt was made to eliminate all these factors together, in view
of the tendency for certain of them to offset others, it is difficult to
escape the conclusion that some factor associated with nationality
apart from those the influence of which could be clearly traced was
concerned with the differences in the mortality found in the various
groups. As to whether there were differences in inborn vitality the
present material affords no basis for a conclusion.

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H O U S IN G CO N G E ST IO N

The influence of housing conditions upon infant mortality seems
especially difficult to trace. In the present section discussion is
limited to the influence of housing congestion as measured b y the aver
age number of persons per room.1
The group of infants on which this discussion is based does not
include infants who died when under 2 weeks of age, nor infants born
in Baltimore who had not lived at least two weeks in the dwelling
occupied by the family, to which the data as to congestion related.
In Table 107 is shown the mortality among infants in f amilies
which lived in varying degrees of housing congestion. The rate was
lowest (52.1) in the group in which the number of persons was less
than the number of rooms and highest (135.7) in that in which the
number of persons averaged two or more to a room.2
T a b l e 107 .— Infant mortality rate, by cause of death and average number o f persons

per room; infants in seven cities who survived two weeks 1
Infant mortality rates 2
Average number of
persons per room

Infants
surviv
ing two
weeks

Infant
deaths

All
causes

Gastric
and
intesti■nal
diseases

Respira
tory
diseases

Epidemic
and
Early
other
infancy communi
cable
diseases

Other
causes

T otal-..............

20,698

1,666

75.7

31.8

18.3

9.1

6.4

10.1

Less than 1. _______
1, less than 2....... ......
2 and o v e r .............. .
Not reported_______

10,837
8,668
1,172
131

565
812
159
30

52.1
94.9
135.7

18.5
42.1
70.8

12.2
23.6
30.7

7.6
10.0
15.4

.4.8
7.6
11.1

9.0
11.6
7.7

1 Excluding a small number of infants who did not live 2 weeks in dwelling of residence (Baltimore).
2 Not shown for “ not reported” group because not significant.

CAU SES OF D E A T H

Table 107 shows also the mortality rates for each of the principal
groups of causes of death. The most marked variations appeared
in the mortality from gastric and intestinal diseases; the rate from
these diseases for infants in families which lived two or more persons
to a room was over three and one-half times that for infants in families
which lived less than one person to a room. But variations in the
deaths from other causes were also found. From respiratory diseases
the rate in families in which the number of persons averaged
two or more per room was about two and one-half times that in
families in which the number of persons was less than the number of
rooms, and the rates from epidemic diseases and from causes peculiar
to early infancy were over twice as high in the former as in the latter
group.
1 For a discussion of the influence of other aspects of housing and associated conditions in Baltimore see
Infant Mortality—Results of a Field Study in Baltimore, M d., based on births in one year, by Anna
Rochester, pp. 106-114 (U. S. Children’s Bureau Publication No. 119, Washington, 1923).
2 For rates in different months of the first year of life see General Table 78, p. 223.

125

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CAUSAL FACTORS IN IN FA N T MORTALITY
TY P E OF F E E D IN G

A considerably larger proportion of the infants in families in which
the number of persons was less than the number of rooms than of those
in families which lived in more congested quarters were artificially fed.
Thus during the third month 22.4 per cent (General Table 79, p. 224)
of the babies in the group with less than one person per room received
artificial food, as compared with only 10.3 per cent of those in the
group in whose homes each room housed on an average three or more
persons; the corresponding percentages in the sixth month were
31.8 and 19.3, and in the ninth 38.3 and 22.8. A greater prevalence
of artificial feeding in the least as compared with the most congested
homes therefore tended to obscure the differences in mortality which
were associated with congestion. If a correction were made for this
factor, the death rates of infants in the least congested homes, rela
tively to those of infants in the most congested homes, would appear
even more favorable than they do in the tables.
C O LO R A N D N A T IO N A L IT Y OF M O T H E R

Table 108 shows that the group of infants who lived in the most
congested homes included a much larger representation of races and
nationalities which had high mortality rates than did that of infants
who lived in the least congested homes. The proportion of babies
whose mothers belonged to these races and nationalities averaged
31.9 per cent, but it was only 22.2 per cent in the group in homes with
less than one person per room and as high as 72.7 per cent in the
group in whose home each room housed on an average three or more
persons.
When allowance was made in Table 109, however, for this over
weighting of the more congested housing groups with an undue
proportion of infants of nationalities which showed high death rates,
the mortality among babies in homes with two or more persons per
room still appeared to be twice as high as that among babies in homes
with a smaller number of persons than of rooms. Though the cor
rection for nationality reduced the high rate associated with the
greatest housing congestion, there remained a decided excess mor
tality that appeared to be associated with overcrowding.
108 .— Proportion o f births to mothers o f nationalities with high infant
mortality rates, by average number of persons per room; infants in seven cities who
survived two weeks 1

T able

Infants who survived two
weeks1—
Average number of persons per room
Total

Born to mothers
of
nationalities
with high infant
mortality ratesa
Number Per cent

T o ta l-

20,698

6,604

Less than 1—
1, less than 22, less than 3.
3 and over.—
Not reported.

10,837
8,568
1,040
132
131

2,405
3,448
565
96
90

31.9

1 Excluding a small number of infants who did not live two weeks in dwelling of residence (Baltimore).
For basic figures see General Table 75, p. 221.
3 Includes French-Canadian, Polish, Portuguese, “ other foreign born,” and colored.

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HOUSING CONGESTION
T

1 0 9 . — Relative infant mortality, by average number o f persons per room,
when influence o f nationality o f mother is eliminated; infants in seven cities who
survived two weeks 1

able

Infant deaths
Average number of persons per room
Actual

1, less than 2______________________________________ _

Ratio of
rate in
specified
Ratio of
group
to
actual to
Expected2 expected
average
(per
cent)4
(per cent)3

1,566

1,565.9

100.0

565
812
159
30

756.9
688. 4
106. 8
13.8

74.6
118. 0
148.9

68.8
125.4
179.3

1 Excluding a small number of infants who lived less than two weeks in dwelling of residence (Baltimore).
3 Expected at average rates prevailing in each nationality group.
3 Not shown for “ not reported” group because not significant.
4 Computed from rates in Table 107.

E A R N IN G S OF FA TH E R

A marked correlation was found between the number of persons
per room and the father’s earnings; the proportion of infants whose
fathers earned less than $650, according to Table 110, was only
28.1 per cent in families in which the number of persons was less than
the number of rooms but was 77.3 per cent in those which lived three
or more persons per room. The question arises whether the high
mortality found to characterize the babies who lived in crowded
quarters was due to housing congestion and its attendant evils or to
other factors associated with low earnings.
After allowance was made in Table 111 for this correlation with
father’s earnings, however, differences in mortality between the con
gestion groups remained, though they were less marked than before.
Evidently, therefore, housing congestion exercised an influence upon
infant mortality apart from any correlation with low father’s earnings.
T

1 1 0 . — Proportion o f births in fam ilies in which father earned less than
$650, by average number o f persons per room; infants in seven cities who survived
two weeks 1

able

Infants who survived two
weeks1—

Average number of persons per room
Total

In families in which
father earned less
than $660

Number Per cent
Total.
Less than 1..
1, less than 2.
2, less than 3.
3 and over...
Not reported.

20,698

8,762

42.3

10,837
8,558
1,040
132
131

3,046
4,711
792
102
101

28.1
55.0
76.2
77.3
77.1

1 Excluding a small number of infants who lived less than two weeks in dwelling of residence (Baltimore).
Por basic figures see General Table 80, p. 224.

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T

CAUSAL FACTORS IN IN FAN T MORTALITY

1 1 1 . — Relative infant mortality, by average number o f persons per room,
when influence o f father’s earnings is eliminated; infants in seven cities who
survived two weeks 1

able

Infant deaths
Average number of persons per room
Actual

1, less than 2___________ ____________ S______________

Ratio of
rate in
specified
Ratio of
group
to
to
Expected2 actual
average
expected (per
cent
)i
(per cent)3

, 1,566

1,566.2

100.0

565
812
159
30

708. 6
728.0
116. 6
13.0

79. 7
111.5
136.4

68. 8
125.4
179.3

1 Excluding a small number of infants who did not live two weeks in dwelling of residence (Baltimore).
2 Expected at average rates prevailing in corresponding father’s earnings groups.
3 Not shown for “ not reported” group because not significant.
* Computed from rates in Table 107.

To ascertain whether the excess mortality associated with the
more crowded dwellings wp,s due to the greater economic pressure
in the larger families Tables 112 and 113 were compiled. The former
shows that the babies in the more crowded dwellings included a
very disproportionate number of those in families with low per capita
income from father’s earnings, and the latter shows the influence
upon mortality associated with housing congestion, when the influence
of variations in economic pressure is eliminated. The analysis shows
that after allowance was made for variations in per capita income
from father’s earnings the effect of housing congestion was still
marked and about the same as after allowance was made for varia
tions in father’s earnings. In other words the latter was practically
equivalent to the former.
T

1 1 2 . — Proportion of births in fam ilies with average per capita income from
father’s earnings o f less than $200, by average number o f persons per room; infants
in seven cities who survived two weeks 1

able

Infants who survived two
weeks1—

Average number of persons per room
Total

In families with per
capita income of
less than $200 2
Number

Per cent

Total.......................................................................................................

20,698

9,992

48.3

2, less than 3___________________________1____________________________

10, 837
8,558
1,040
132
131

2,783
6,106
916
114
73

25.7
71.3
88.1
86.4
55.7

1 Excluding a small number of infants who did not live two weeks in dwelling of residence (Baltimore)
and infants whose fathers earned $1,250 or more. For basic figures see General Table 81, p. 224.
2 From father’s earnings. Father’s earnings of $1,250 and over not classified according to per capita in
come from father’s earnings.

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HOUSING CONGESTION
T

113.-^—Relative mortality, by average number o f persons per room, when
influence o f economic pressure as measured by the average per capita income from
father's earnings is eliminated; infants in seven cities who survived two weeks 1

able

Infant deaths
Average number of persons per room
Actual

Total_______ _____ _________
Less than 1_____________ _ . .
1, less than 2 ___ _____ __________
2 and over________
Not reported.. ________

____

Expected2

Batio of
actual to
expected
(per cent)3

1,566

1,566.1

100.0

565
812
159
30

679.9
753. 5
122.0
10.7

83.1
107.8
130.3

i Excluding a small number of infants who did not live two weeks in dwelling of residence (Baltimore).
3 Expected at average rates in each per capita income group, irrespective of the number of persons per
room.
3 Not shown for “ not reported” group because not significant.

E A R N IN G S OF F A T H E R A N D N A T IO N A L IT Y OF M O T H E R

The high correlation found between housing congestion and both
earnings of father and nationality of mother suggests that the com
bined influences of these two factors may have accounted for a con
siderable part of the effect upon mortality associated with housing
congestion. But Table 114, m which both factors were eliminated,
shows that, apart from both, housing congestion exerted a marked
influence upon the death rates.
T

1 1 4 . — Relative mortality, by average number o f persons per room , when
influence o f earnings o f father and color and nativity o f mother is eliminated;
infants in seven cities who survived two weeks 1

able

Infant deaths
Average number of persons per room
Actual

Total..........................................
Less than 1........................................
1, less than 2_________________
2, less than 3__________
3 and over....... ...................
Not reported...................

Batio of
to
Expected 2 actual
expected
(per cent)3

1,566

1,566.0

100.0

565
812
139
20
30

697.1
734.8
107.1
13.7
13.3

81.1
110.5
129.8
146.0

1 Excluding a small number of infants who did not live two weeks in dwelling of residence (Baltimore).
2 Expected at average rates in each group classified by earnings of father and color and nativity of mother!
irrespective of average number of persons per room.
3 Not shown for “ not reported” group because not significant.

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CAUSAL FACTORS IN IN F A N T MORTALITY

ances were made for the correlation between housing congestion on
the one hand and earnings of father and nationality of mother on the
other, this apparent excess mortality among babies in the most
congested dwellings was reduced to about twice that among babies
in the least congested homes.
The analysis by cause of death showed differences as between the
groups classified according to the degree of crowding within the
dwelling in the mortality from gastric and intestinal, from respiratory,
and from epidemic and other communicable diseases. These differ
ences may be attributed to the association of congested living quarters
with greater difficulty of keeping away infections of various kinds
from the babies, and to the association of such quarters with lack
of cleanliness in connection with the baby’s food and with lack of
fresh air.

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EC O N O M IC F A C T O R S 1

The economic factors in infant mortality treated in the present
analysis are the mother’s employment during the period of pregnancy
and during the first year of the baby’s life, the father’s earnings, and
the family’s per capita income from the father’s earnings. Each of
these factors may exert an indirect influence through its effect
upon the mother’s health or upon the care given the infant.
It should be emphasized that in every case these various economic
conditions were directly related to the particular infant whose
chances of life might be affected. Thus the data as to the father’s
earnings related to the amount earned during the year immediately
following the baby’s birth— that is, during the period when his
earnings would be closely associated with the infant’s chances of life;
and the information as to the mother’s employment related to work
during the period of pregnancy preceding and, if the baby was alive
at the time work was begun or resumed, to work during the year
following the infant’s birth.
E M P L O Y M E N T O F M O T H E R D U R IN G PR E G N A N C Y

The information obtained concerning the mother’s employment
during the period of pregnancy included statements as to whether
she had worked at home or away from home, her specific occupation,
and the interval between cessation of work and confinement. As
gainfully employed were classed all mothers who had worked for
wages or for salaries, had kept boarders or lodgers, had done factory
work at home for pay, or had helped in their husbands’ business.
So far as the severity of the labor performed either by the mothers
who had been gainfully employed at home or away from home or
by those who had not been employed is concerned, no information
was obtained except such as might be inferred from the nature of
their occupations. Even the mothers reported as not employed
may have done housework involving long hours and heavy labor.
The comparison, therefore, is not between women who had worked
and other women who had enjoyed leisure but between women who
had engaged in a regular occupation, often with housework in addi
tion, and other women who had done only housework.
Nearly one-third of the mothers of live-born infants had engaged
in gainful labor either at home or away from home during the period
of pregnancy. Slightly over half of these had been employed at
home and the rest— over one-eighth of the entire number— away
from home.
The mortality rate for the infants of mothers who had been em
ployed away from home during pregnancy, as shown in Table 115,
was 176.1-—1.8 times the rate (98) for those whose mothers had not
bgen employed. For the infants of mothers employed at home, on
le other hand, it was 114.6— or only one-sixth higher than the rate
for those whose mothers had not been employed.
1A summary of this chapter was published in the Quarterly Publications of the American Statistical
Association, Vol. X IX , pp. 137-155 (June, 1924).

131

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132

CAUSAL FACTORS IN IN FAN T1 MORTALITY

T a b l e 115 .— In fan t mortality rates, by cause o f death and em ploym ent o f mother
during pregnancy; live births in eight cities
Infant deaths from specified causes

Employment of mother during
pregnancy

Live
births

All causes

Gastric and intesti
nal diseases

Respiratory
diseases

Infant
Infant
Infant
Number mortality Number mortality Number mortality
rates 1
rates1
rates 1
Total...................... .........
Employed away from home___
Employed at home...................
Not employed..........._
Not reported...........

22,967

2,555

111.2

743

32.4

450

19.6

3,084
3,788
16,089
6

543
434
1,576
2

176.1
114.6
98.0

191
138
412
2

61.9
36.4
25.6

103
95
252

33.4
25.1
15.7

Infant deaths from specified causes

Employment of mother during pregnancy

Early infancy

Epidemic and other
communicable
diseases

Other causes

Infant
Infant
Infant
Number mortality Number mortality Number mortality
rates i
rates 1
rates 1
Total___________

830

36.1

162

7.1

370

16.1

Employed away from hom e...
Employed at home________
Not employed______

155
103
572

50.3
27.2
35.6

34
33
95

11.0
8.7
5.9

60
65
245

19.5
17.2
15.2

1 Not shown for “ not reported” group because not significant.

Causes o f death o f infant.

The variation, according to mother’s employment during preg
nancy, of mortality from gastric and intestinal diseases, from respira
tory diseases, and from epidemic diseases, as Table 115 shows, was
similar to that of the mortality from all causes; the rates were lowest
for the infants whose mothers had not been employed and highest
for those whose mothers had been employed away from home. The
rate from causes peculiar to early infancy, on the other hand, was
lowest not for the babies of the “ not employed” but for those of the
“ employed at home” group of mothers; but it was highest for the
babies of the “ employed away from home” group.
Neonatal mortality.

This tendency for the mortality to be excessive among infants of
mothers who had been employed away from home during pregnancy
was found also in the neonatal rates. Among the babies of the
“ employed at home” group, on the other hand, the neonatal mor
tality, like that from causes peculiar to early infancy, was lower
even than that for the babies of the “ not employed” group.1“ The
unusually low figures (shown in Table 116) for the group of mothers
who had been employed at home may have been due in part to the
fact that the amount and character of the work done by these mothers
was similar to that done in performing their ordinary household and
1 ° For rates in later months see General Table 82, p. 225.

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133

ECONOMIC FACTORS

family duties by mothers who were not gainfully employed, and in
part, perhaps, to a tendency on the part of the mothers who were
in poor physical condition not to engage in gainful labor. The
“ not employed ” group of mothers may actually have been somewhat
unfavorably weighted by the inclusion of certain mothers who would
have been in one of the other groups if they had enjoyed normal
health. That the infants whose mothers had been employed away
from home during pregnancy showed higher death rates than those
whose mothers had not been so employed or had not been employed
at all was, in any case, significant evidence of the influence of this
type of employment.
Interval between cessation o f work and confinement.

Of the mothers who had been gainfully employed away from home
a small proportion (13.3 per cent) had been thus employed until
within one month of confinement, more than half of these reporting
working practically to the date of the baby’s birth. According to
Table 116, a markedly higher mortality was found among the infants
of these mothers than among those whose mothers had stopped
work one month or more before confinement. In the comparatively
small group of babies born to mothers who reported no interval
between cessation of work away from home and the birth, the mor
tality rate was 244.2, as compared with 187.5 for babies of mothers
who had intervals of rest of less than one month, and with 169.3
for those of mothers who had intervals of rest of one month or
more.
T a b l e 116 .— In fan t mortality and neonatal mortality rates, by place o f em ploym ent
o f mother during pregnancy and interval between cessation o f work and confine
m ent; live births in seven cities
Infant deaths
Employment of mother during pregnancy and inter
val between cessation of work and confinement

Under 1 month

Live
births
Total

Infant
mor
tality
rates1

Number

Neonatal
mortal
ity rates1

Total________________________________ _____

21,536

2,368

110.0

954

44.3

Mother employed away from home________________

3,071

540

175.8

193

62.8

No interval____________ ______ _________ ______
Interval under 1 m onth......... ........... ................ .
Interval 1 month and over____________________
Interval not reported.._______________________

217
192
2,634
28

53
36
446
5

244.2
187.5
169.3

24
16
153

110.6
83.3
58.1

Mother employed at home............... ............ ..............

3,535

386

109.2

123

No interval...________ ____ _____ ___________
Interval under 1 month....................... ................
Interval 1 month and over____________________
Interval not reported_______________________

2,683
214
598
40

278
31
70
7

103.6
144.9
117.1

14,924
6

1,440
2

96.5

Mother not employed____________________________
Employment of mother not reported_______________

84 •
12
25
2
638

34.8
31.3
56.1
41.8
42.7

i Not shown where base is less than 100.

The neonatal mortality rate was likewise much higher for infants
of mothers employed away from home who reported little or no inter
val of rest before confinement than for those of mothers who reported
96515°— 251------ 10

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134

C A U SAL, F A C T O R S I N

I N F A N T M O R T A L IT Y

intervals of at least one month; it was 110.6 for those of the “ no
interval” and 83.3 for those of the “ less than one month” group, as
compared with 58.1 for the “ one month and over” group. These
figures should also be contrasted with the neonatal mortality rate of
42.7 for babies whose mothers had not been gainfully employed.
Among the infants of mothers who had worked at home during
pregnancy a somewhat different situation was found. In this group
the mortality rate for babies whose mothers had less than one month
of rest before confinement was 144.9, as compared with a rate of
117.1 for babies whose mothers had rest intervals of one month or
more. But therateforinfants of mothers who reported no interval of
rest was lower than that for either of these groups. The neonatal rate,
likewise, was lowest for the group of infants whose mothers reported
no interval of rest before confinement— 31.3 as compared with 56.1
for the infants of mothers who had less than one month’s rest and
41.8 for those of mothers who had rest periods of one month or more.
A plausible explanation is. that the work of the mothers who had no
rest before the birth of the child was not usually of an arduous type
and did not involve heavy physical labor.
Prematurity.

As Table 117 shows, the proportion of premature births to mothers
who had been employed away from home was greater than for either of
the other groups— 6.1 per cent as compared with 5.2 per cent for the
group of mothers who had not been employed and with 3.5 per cent
for the group employed at home. The relatively high proportion of
remature births to mothers who had not been employed may have
een due in part, as has already been suggested, to the inclusion in this
group of an unduly large proportion of mothers who were not in good .
health.
Though the greater prevalence of premature births to mothers who
had been employed away from home tended to explain in part the
higher mortality among these infants, it failed to account fully for
their higher rate from all causes or even for their higher rate from
causes peculiar to early infancy. Greater mortality was found among
the infants born at term to mothers who had worked away from home
than among other full-term infants.

able

1 1 7 .- —Proportion

o f premature births, by employment of mother during
pregnancy; live births in eight cities
Live births

Employment of mother during pregnancy

Premature births
Total
Number

Not~employed - _____________________________________________________

Per cent

22,967

1,158

5.0

3,08'4
3,788
16,089
6

187
131
840

6.1
3.5
5.2

Type o f feeding.

A slightly larger proportion of the inf ants of mothers who had been
employed away from nome during pregnancy were artificially fed

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135

ECONOMIC FACTORS

than of the infants whose mothers had worked at home or of those
whose mothers had not worked during this period. In the third
month of life, for example, the percentages artificially fed were 16.7
for infants of mothers who had been employed at home, 20.9 for those
of mothers who had not been employed, and 22.2 for those of mothers
who had been employed away from home. The corresponding per
centages for the ninth month of life were 31, 34.8, and 40.3, respec
tively.2
The greater proportion artificially fed in the group of infants whose
mothers had been employed away from home accounted for a part
of the higher mortality among them, especially from those diseases
most closely associated with type of feeding.
The markedly lesser prevalence of artificial feeding among the
infants of mothers who had been employed at home during pregnancy
also tended to account for the somewhat lower mortality among these
infants.
Color and nationality o f m other.

Nearly three times as large a proportion of the infants whose mothers
had been employed away from home during pregnancy as of those whose
mothers had not been employed, according to Table 118, were of
race or nationality groups which had higher than average mortality
rates— 65.7 per cent as compared with only 23 per cent.
The excessive mortality found associated with the mother’s em
ployment away from home, therefore, was accounted for in part by
the correlation of such employment with nationality groups having
high-rates. Table 119 shows, however, that this correlation was
responsible for only a relatively small part of the high mortality
among infants of mothers who had been employed away from home
during pregnancy. In each nationality group a markedly greater
mortality was found— though not so great as that found when no
allowance was made for influence of race and nationality of mother—
among infants of mothers who had been employed away from home
than among those of either of the other two groups of mothers.
T

118 .— Proportion o f births to mothers o f nationalities with high infant mor
tality rates, by employment o f mother during pregnancy; live births in eight cities

able

Live births—

Employment of mother during pregnancy
Total

To mothers of na
tionalities with
high infant mor
tality rates »
Number Percent11

Total.......................................... .
Employed away from home........... .
Employed at home.........
Not employed............
Employment not reported______•

22,967

7,428

32.3

3,084
3,788
16,089
6

2,027
1,702
3,697
2

65.7
44.9
23.0

» Including French-Canadian, Polish, Portuguese, “ other foreign born,” and colored. Compare with
Table 99, p. 118.
b Not shown where base is less than 100.
3See General Table 84, p. 225.

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136
T

CAU SAL FACTORS IN

IN F A N T M O R T A L IT Y

1 1 9 . — Relative infant mortality, by employment o f mother during pregnancy,
when influence o f color and nationality of mother is eliminated; live births in eight
cities

able

Infant deaths
Employment of mother during pregnancy
Actual

TotaL__________ _____ __________________________ ;_______

Expected 1

Ratio of
actual to
expected
(per cent)2

2,555

2,555.3

100.0

543
434
1,576
2

420.1
439.8
1,694. 6
.8

129.3
98.7
93.0

1 Expected if the average infant mortality rate for each color and nationality group applied to all live
births of that nationality, irrespective of the employment of the mother during pregnancy.
2 Not shown for “ not reported” group because not significant.

Earnings o f father.

According to Table 120, a much larger proportion of the infants
of mothers who had been employed away from home (70.6 per cent)
than of those of mothers who had been employed at home (53.4 per
cent) or of those of mothers who had not been employed (34 per cent)
were born in families in which during the year following the baby’s
birth the father earned less than $650. A marked correlation existed,
therefore, between father’s earnings and the prevalence of mother’s
employment. Since the death rate was high for infants whose
fathers’ earnings were low, the question is pertinent whether the
excessive mortality among babies whose mothers had been employed
away from home was due to the disproportionate weighting of this
group with babies whose fathers’ earnings were low, or whether, even
after full weight was given to the effect of this association, the em
ployment of the mothers still seemed to have exerted an influence over
the rate.
When allowance was made in Table 121 for the correlation between
low earnings of father and employment of mother, the infants of
mothers who had been employed away from home during pregnancy
were found to have had a mortality markedly higher than that among
the infants either of mothers who had been employed at home or of
mothers who had not been employed. The rates for the two lastmentioned groups appeared to be almost equal when allowance was
made for the correlation between father’s earnings and mother’s
employment.
T

able

1 2 0 . — Proportion o f births in fam ilies in which father earned less than $650,
by employment of mother during pregnancy; live births in seven cities 1

Live births— : :>
Employment of mother during pregnancy
Total

In families in which
father earned less
than $650
Number

Total______ ____ _________________________________________ .
Employed away from home______________________________________
Employed at home. . . . ______________________________ ____ _
N otem ployed2_________ ____ _________________ ____________ ___
1 Compare with Table 150.

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Per cent

21,536

9,133

42.4

3,071
3, 535
14,930

2,167
1,889
5,077

70.6
53.4
34.0

3 Including births to mothers for whom employment was not reported.

137

E C O N O M IC F A C T O R S
T

able

1 2 1 . — Relative mortality, by employment o f mother during pregnancy, when
influence of father’s earnings is eliminated; live births in seven cities

Infant deaths
Employment of mother during pregnancy
Actual

Total________ ________ . . .
Employed away from hom e.................. ................
Employed at home______________
Not employed__________ _____
Employment not reported..................................

Expect
ed i

Ratio of
actual to
expected
(per
cent)2

2,368

2,368.2

100.0

640
386
1,440
2

404.0
420.1
1,543. 2
0.9

133.7
91.9
93.3

1 Expected if average infant mortality rate for eaeh father’s earnings group applied to all live births in
the group, irrespective of the employment of mother during pregnancy.
2 Not shown for “ not reported” group because not significant.

When allowance was made for both earnings of father and color
and nativity of mother jointly, as in Table 122, the mortality among
infants whose mothers were employed during pregnancy still appeared
about 40 per cent higher than that among infants whose mothers
were not gainfully employed.
T

1 2 2 .— Relative mortality, by employment o f mother during pregnancy, when
influence of earnings o f father and color and nativity of mother is eliminated; live
births in seven cities

able

Infant deaths
Employment of mother during pregnancy
Actual

Ratio of
Expected1 of actual to
expected
(per cent)

Total__________ _________________________________________

2,368

2,368.0

100.0

Employed away from home____ ________________________________
Employed at home________________________________________
Not employed________ _______ _______________________
Not reported______ _____________ ______ _______________

640
386
1,440
2

409.7
425.6
1,532.0
.8

131.8
90.7
94.0

1Expected at average rates for infants of the same earnings-of-father and color-and-nativity-of-mother
groups, irrespective of employment of mother during pregnancy.

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CA U SAL, F A C T O R S I N

I N F A N T M O R T A L IT Y

per cent at home during the later period; and of those who had been
employed at home during pregnancy 2.5 per cent were later em
ployed. away from and 85 per cent at home. On the other hand, of the
mothers who had not been employed during the period of pregnancy
only 6.6 per cent were employed either at home or away from home
during the infant’s first year of life. (See General Table 86, p. 226.)
T a b l e 123 .— Employment o f mother away from home during first year o f infant’ s

life, by her employment during pregnancy; live births in eight cities 1
Live births—

Employment of mother during pregnancy
Total

To mothers em
ployed a w a y
from home dur
ing first year of
infant’s life
Number Per cent

Total_____ _________________________ ."1..........................- ................

22,967

1,742

7.6

Employed away from home__________________________________________
Employed at home___________ ____
______________________________

3,084
3,788
16,095

1,285
96
361

41.7
2.5
2.2

1 For basic figures see General Table 86, p. 226.
3 Including cases in which mother’s employment was not reported.

It is evident, therefore, that the mother’s employment during the
period of pregnancy was closely associated with her employment
during the first year of the infant’s life and that any conclusion as to
the influence of the former over the prevalence of gastric and in
testinal diseases must take into account the marked influence of the
latter over the prevalence of artificial feeding. This point is discussed
in the following section (p. 142).
Causes o f employment o f mother during pregnancy.

The causes of the employment of mothers during pregnancy were
doubtless similar to those of the employment of married women in
general and were primarily economic. The influence of the economic
factor was shown very clearly in the much greater proportions of
mothers found to have been employed in the lower as compared with
the higher earnings-of-father groups; this subject is discussed in detail
in the section dealing with father’s earnings (pp. 158-160). On the
other hand, even in cases in which the father’s earnings were the same,
marked variations were found between the different race and nation
ality groups in the proportion of mothers who worked away from
home during pregnancy. Evidently under the same conditions of
economic pressure the traditions and customs prevailing in each such
group had a powerful influence in determining whether or not the
mothers should go to work (pp. 118-119).
Summary.

Nearly one-third of the mothers had been gainfully employe
during pregnancy, 55 per cent of them at home and 45 per cent away
from home.
The gainful employment of the mother at home was found to have
been associated with slightly higher infant death rates from all, c&uses

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ECONOMIC FACTORS

139

and from gastric and intestinal and respiratory diseases, but with a
slightly lower neonatal mortality, with a somewhat lower rate from
causes peculiar to early infancy, and with a lower percentage of
premature births than were found for babies of mothers who had not
been employed at all. The higher mortality in early infancy among
babies whose mothers had not been employed, as compared with that
among infants of mothers who had been employed at home during
pregnancy, may have been due in part to the fact that the former
group included mothers who, except for ill-health, would have been
at work. Furthermore, the fact that mothers were not gainfully
employed did not mean that they were at leisure; in most cases,
doubtless, such mothers were occupied with housework, sewing, and
the care of children—work probably not very different from that
performed b y the mothers employed at home. The evidence does not
indicate that the mother’s gainful employment at home during
pregnancy was especially harmful to the infant.
Employment of the mother away from home during pregnancy, on
the other hand, was associated with a high mortality from all causes,
from gastric and intestinal and respiratory diseases, and from causes
peculiar to early infancy, with a high neonatal mortality, and with a
high percentage of premature births. The influence of such employ
ment was found to nave been greater the shorter the interval o f rest
before confinement. About one-eighth of the total number of births
were to mothers who were employed away from home during preg
nancy. Such employment exerted an influence over infant mortality
irrespective of any correlation with nationality of mother or with
father’s earnings, and its influence over the proportion of premature
births and over mortality in early infancy was evidently independent
of any correlation with the mother’s employment during the first
year of the infant’s life.
E M P L O Y M E N T OF M O T H E R D U R IN G FIRST Y E A R OF IN F A N T ’ S LIFE

According to Table 124, slightly over one-fourth of all the births
were to mothers who were gainfully employed either at home or
away from home during some part of the infant’s first year of life.
Of these employed mothers more than seven-tenths worked at home;
less than one-third— or about one-twelfth of the total number in the
eight cities— worked away from home.
Since in many cases the mothers did not go to work until their
babies were nearly a year old, furthermore, this proportion (onetwelfth) tends to overstate the importance of the employment of
mothers away from home as an influence upon the mortality rate.
Of the months lived b y all the infants from birth up to the end of the
first year only 4.5 per cent (one-twenty-second) were lived b y babies
after their mothers had begun or resumed work away from home.
Only one-fifth of the mothers who were employed away from home
during their infants’ first year of life, according to Table 125, began
such work before the end of the second month; but over half of them
had begun by the end of the fifth month. On the other hand, of the
mothers who were employed at home during this period over half
(56 per cent) began within one month, and b y the end of the third
month over three-fourths were at work.

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T a b l e 124 .— Employment of mother during first year of infant’ s life; infants in

eight cities .
Months lived from time
mother went to work
to end of first year

Live births
Employment of mother during first year of
infant’s life
Number

Total......................................................................

Per cent
distribution

Number

22,967

100.0

253,853. 00

100.0

1,742
4,337
16,887
1

7.6
18.9
73. 5

1 11,377. 75
839,432. 50
8 203,042. 75

4.5
15.5
80.0

i Excluding months lived by 3 infants whose ages at the time their mothers went to work were not rePtarExcluding months lived by 59 infants whose ages at the time their mothers went to work were not re8Including cases in which mother’s employment was not reported.
8 Place of employment not reported.
T a b l e 125 .— Age o f infant when mother went to work , by place o f mother’ s employ

ment; infants in eight cities whose mothers went to work during first year o f infant s
life

Month of infant’s life in
which mother resumed
work

5 months! under 6______

Infants whose mothers
were employed during
first year of infant’s
life—

Month of infant’s life in
which mother resumed
work

Total

Away
from
home

i 6,080

1,742

4,337

6 months, under 7----------

2,533
' 872
511
444
287
258

105
243
233
242
143
151

2,428
629
278
202
144
107

8 months, under 9______
9 months, under 10______
10 months, under 11....... 11 months, under 12___ _
Not reported___________

At
home

Infants whose mothers
were employed during
first year of infant’s
life—

Total

276
200
215
189
156
76
1 63

Away
from
home
144
111
138
99
84
46
3

At
home
132
89
77
90
72
30
59

i Including one case for which neither the place of the mother’s employment nor the infant’s age when
she began work was reported.

Obviously any true comparison of the mortality among infants
whose mothers were employed with that among infants whose
mothers were not employed must take into account the different
ages of the infants at the time when their mothers commenced work.
In this process account must be taken not only of the varying prob
abilities of dying at the different ages but also of the varying lengths
of time during which the babies were exposed to the risk of death.
Thus an infant whose mother went to work at the beginning of the
twelfth month had a smaller probability of dying within one month
than an infant whose mother went to work at the beginning of the
third month; but, even apart from differences in the mortality
rates at these ages, the baby whose mother went to work at the
beginning of the twelfth month, other things being equal, had a
risk of dying before his first birthday only one-tenth as great as that
of the baby whose mother went to work at the beginning of the third
month, since the latter had 10 times as long to live before reaching
his first birthday.

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E C O N O M IC F A C T O R S

The mortality among infants whose mothers were employed dur
ing the infants’ first year of life, as compared with that among infants
of mothers who were not employed, can best be presented, therefore,
in the form of a comparison between the deaths that actuallyjjccurred
in the former group and those that would have occurred if the mor
tality rates o f babies o f the same ages in the latter group had pre
vailed in it.' Such comparisons of actual and expected deaths are
presented in the following tables.
Causes o f death.

According to Table 126, among the infants whose mothers were
employed away from home during the infants’ first year of life 168
deaths occurred, or nearly two and one-half times as many as the
number (67.8) that would, have been expected at average rates for
the corresponding ages. This excess mortality was found especially
in deaths from gastric and intestinal diseases, which were over three
times as numerous as they would have been if average rates had
prevailed. The mortality from respiratory diseases was twice as
high as the average.
No significant differences from the average rates were found, on
the other hand, for the infants whose mothers were employed at home.
In other words, the extra hazard found associated with the mother’s
employment away from home does not appear to have extended to
these babies whose mothers worked at home.
T

1 2 6 .— M o r ta lity a m o n g in fa n ts o f m others em p lo ye d d u rin g first y e a r o f
in fa n t’s life as com p a red w ith average m o rta lity a m o n g all in fa n ts, b y ca use o f
death an d place o f m other’ s e m p lo y m e n t; in fa n ts i n eight cities

able

Deaths of infants whose mothers during first year of infant’s
life were employed— , .

Cause of death

At home

Away from home

Actual

Ratio of
Expect actual
to
ed i
expected

Actual

All causes___________ - ___ ____ ___

168

67.8

2.5

282

262.6

1.1

Gastric and intestinal diseases----------------Respiratory diseases......._............................
Epidemic and other communicable dis-

101
39

31.1
17.8

3.2
2.2

122
78

114.8
66.1

1.1
1.2

7
21

6.7
12.2

1.0
1.7

27
55

24.2
57.5

1.1
1.0

O th e r ...... _______________ _______ ____

* Expected at average mortality rates from specified cause in each month of life.
rates for the second two weeks were used.

In the first month the

Interval between confinement and resumption o f work.

According to Table 127, the excess mortality associated with the
mother’s work away from home was greater the earlier such work was
begun or resumed after the birth. Thus the babies whose mothers
were employed away from home beginning when the baby was less
-than 2 months old had a mortality three times the average, and those
whose mothers began such work when the baby was between 2 and
9 months old had a mortality about twice the average. On the other
hand, the babies whose mothers were employed at home appeared
to have been subject to average mortality rates even in cases in which

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the mother commenced work when the baby was less than a month
old. Presumably in these cases the work at which the mother was
employed was not arduous and did not lessen the amount of care
which she could give her infant.
T

able

1 2 7 .— M o r ta lity a m o n g in fa n ts w h ose m others w ere e m p lo y e d a s com p a red
w ith average m orta lity ra te s; in fa n ts i n eight cities '

Deaths of infants whose mothers during first year of infant’s
life were employed—
Month of infant’s life in which mother
went to work

Away from home

Actual

Total_______

168

First................. .
Second....................
Third......................
Fourth...................
Fifth.......................
Sixth_____________
Seventh and eighth
Ninth to twelfth...

At home

Ratio of
Expected1 actual to
expected

Actual

Ratio of
Expected1 actual to
expected

70.6

2.4

282

263.2

7.8
15. 9
13.3

3.2
2.9
1.7

216
31
16
2
3
8

178.1
41. 0
15.8
10. 0

1.2
.8
1.0
2.2

3.7
5.7

2.8

12. 0

6.0
5.2

6.4
3.9

2.6

2.5
2.3
1.9

1.0

6.1

.2
.5

0.2

1.8

m1
averJa%e mortality among all infants. The figures are the sum of two separate calculations:
1 o trie cie;itns expected at average mortality for the remainder of the first year among the infants surviving
at the beginning of the month immediately following that in which the mother went to work were added
the deaths expected at average monthly death rates from the time the mother went to work to thebeginnext month; it was assumed for the purpose of calculation that no mothers commenced work
within two weeks of the birth. The slight difference in the number of expected deaths in Tables 126 and
127 is explamed by the difference in the method of calculation.

Type o f feeding.

Of the months lived prior to the end of the ninth but after the
mothers’ employment had begun, by infants of mothers who were
employed away from home during any part of this period, as Table
128 shows, a much larger proportion were months of artificial feeding
than of those lived by infants of mothers who were not employed—I
51.4 per cent as compared with 24 per cent. The percentage of
months during which artificial food was given was a trifle lower,
however, for the babies whose mothers were employed at home than
for those whose mothers were not employed at all. To a slight ex
tent the prevalence of artificial feeding among the infants of mothers
who were employed away from home may have been due to the
tendency toward an increasing resort to such feeding in the later
months of life; but both in the early and in the later months arti
ficial food was markedly more often given to the babies whose mothers
were employed away from home than to other babies.3
When allowance was made in Table 129 for the greater prevalence
of artificial feeding among the infants of mothers who worked away
from home, it appeared that the excess mortality among them was
considerably reduced though not entirely eliminated. In other
words, part of the high mortality associated with the mother’s
employment away from home was due to the associated tendency '
toward a greater recourse to artificial food.
See also General Tables 87,88, and 89, pp. 227,228.

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T

able

1 2 8 .—

Prevalence o f artificial feeding, by employment of mother; infants in
eight cities
Months lived from birth to end of
ninth
Months of artificial
feeding

Employment of mother
Total

Number

Per cent

192,212.50

47,842.00

24.9

6,891.00
27, 585.25
157,736.25

3,540. 00
6,387.75
37,914.25

51.4
23.2
24.0

1 Including cases in which mother’s employment was not reported.
T

1 2 9 . — Mortality among infants whose mothers were employed during first
year of infant’ s life as compared with that among infants whose mothers were not
employed, when influence of difference in type o f feeding is eliminated; infants
in eight cities

able

Deaths of infants whose mothers during first year of
infant’s life were employed—A'i,*,
Away from home

At home

Type of feeding
Actual

Ratio
Ex
of actual
to ex
pected1
pected

Actual

Ratio
Exof actual
pected1 to ex
pected

T otal..

168

85.5

2.0

282

240.8

1.2

Breast______
Partly breast
Artificial.. ...
Not reported.

7
42
119

4.6
14.5
65.6
.9

1.6
2.9
1.8

80
52
150

74.1
4L 2
124. 7

1.1
1.3
1.2

...........

1 Expected if rates for each month of life and type of feeding found for infants whose mothers were not
employed had prevailed among these infants.

Color and nationality o f mother.

According to Table 130, a much larger proportion of the infants
whose mothers were employed away from home than of either those
whose mothers were employed at home or those whose mothers
were not employed were of nationality groups which had high death
rates— 69.5 per cent as compared with 43.4 per cent and 26 per cent,
respectively. In part, therefore, the excess in the mortality among
the infants of mothers who were employed outside the home may
have. been due to the overweighting of this group with babies of
nationalities which had. unusually high rates.
When allowance was made in Table 131 for this correlation be
tween mother’s employment and nationality it was found, however,
that the infants of mothers who were employed away from home
still appeared to be subject to an excessively high death rate. In
"other words, when in each nationality group the rate for babies of
employed mothers was compared with that for other babies a de
cided tendency toward greater mortality in the former group was
observed.

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1 3 0 . —-Proportion o f births to mothers o f nationalities with high infant
mortality rates, by employment o f mother during first year o f infant’s life; infants
in seven cities

able

Live births—
To mothers of nationalities^with high in
fant mortality rates 1

Employment of mother during first year of infant’s life
Total

Number
Total____________________________
Employed away from home___ __________________
Employed at home____ _____ __________
Place of employment not reported________
Not employed_______ _____
1 Including

Per cent

21,536

6,904

32.1

1,730
4,091

1,203
1,774

69.5
43.4

4,082

26.0

15,714

Freneh-Canadian, Polish, Portuguese, “ other foreign horn,” and colored.

1 3 1 . — Mortality among infants in eight cities whose mothers were employed
during first year of infant’s life as compared with average mortality in the same
color and nativity groups

able

Deaths of infants whose mothers during first year of infant’s
life were employed—
Color and nativity of mother

Away from home

Actual

Ex
pected

At home

Ratio of
actual to
expected

Actual

Ex
pected

Ratio of
actual to
expected

Total____________________________

168

96.7

1.7

282

281.4

1 .0

White.................. ........................................
Native___________ ____ _____
Foreign born_______ ____
Colored..............................

129
42
87
39

69.0
13.3
55.7
27.7

1.9
3.2

261
55
206

253.7
56. 5
197.2
27.7

1 .0
1 .0
1 .0

1 .6

1.4

Expected at average rates for each month-of-life and each color-and-nationality group.

Earnings o f father.

According to Table 132 a much larger proportion of the infants
whose mothers were employed away from nome during the infant’s
first year of life (79 per cent) than of those whose mothers were
employed at home (54.1 per cent) or of those whose mothers were
not employed (35.3 per cent) were born in families the fathers of
which earned less than $650. In other words, a marked correlation
was found between the prevalence of mother’s employment and low
father’s earnings. The question is thus raised: Was the relatively
high mortality among the infants of mothers who were employed
away from home due to factors associated with low income from
father’s earnings or to factors associated with the employment of the
mother ?
When allowance was made in Table 133 for this interrelation be
tween the mother’s employment and the low income from father’sP
earnings the mortality among infants whose mothers were employed
away from home was still 1. 6 times the average rate.

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E C O N O M IC F A C T O R S
T

1 3 2 .— Proportion o f births in fa m ilies in which father earned less than $ 6 6 0 ,
by em ploym ent o f mother during first year o f infant’ s life; infants in seven cities

able

Live births—
In families in which
father earned less
than $650

Employment of mother during first year of infant’s life
Total

Number

Per cent

Total____ _____ ________________________________________ .

21,536

9,133

42.4

Employed away from home................................................................ ...........
Employed at home................. ...................................................................... _
Not employed 1 _________________________ _______ ____ ____

1,730
4,091
15,715

1,367
2,214
5,552

79.0
54.1
35.3

1 Including

births to mothers for whom employment was not reported.

T a b l e 1 3 3 . — Mortality among infants in seven cities whose mothers were employed

during first year o f infant’s life as compared with average, by earnings of father
Deaths of infants whose mothers during first year of infant’s
life were employed—
Earnings of father

Away from home

Actual

Ex
pected

At home

Ratio of
actual to
expected

Actual

Ex
pected

Ratio of
actual to
expected

T ota l-.___________________ _______

159

96.6

1 .6

222

262.1

0 .8

Less than $450.......................................... ...
$450-$549__________ _____ ______________
$550-$649____________________ __________
$650-$849____________ __________________
$850 and over___ _ _____________ _____ _
No earnings__________
______________
Not reported.................................................

58
32
27
. 15
3
18

41.2’
18.2
10.4
7.6
1.5
14.4
3:3

1.4

1 .8

89.2
49.0
34.5
44.5
28.5
9.3
7.1

.8
.8
.8
.8

1.3

75
37
27
35
39
7

1 Expected

1 .8
2 .6
2 .0
2 .0

1.4
.8

at average rates for each earnings group and month of life.

Causes o f mother’s employment during infant’s life.

The causes which led to the employment of these mothers during
their babies’ first year of life were doubtless similar not only to those
which bring about the employment of married women in general but
also to those, already discussed, which led to the employment during
pregnancy of mothers of infants included in this study (p. 138).
That economic factors were primarily responsible is shown by the
much greater proportion of mothers found to have been employed
in the lowest as compared with the higher earnings-of-father group.4
Under the same degree of economic pressure, however, a much smaller
proportion of mothers went out to work during the infant’s first
year of life than during pregnancy. Besides low father’s earnings
the traditions and customs prevailing in each race and nationalitygroup appeared to have exerted an influence over whether or not
'fee mother sought gainful employment (pp. 119-121).
4

See tables and discussion, pp. 160-161.

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Summary.

The mother’s employment at home during the infant’s life, which
was a possible influence oyer one-sixth of the total number of months
under 1 year of age lived by all the babies included in the study,
was found to have been associated with average mortality rates.
The babies whose mothers worked at home received slightly more
favorable feeding than was received by those whose mothers did
not work at all, but the group was overweighted b y infants of
nationalities having high death rates and by infants whose fathers’
earnings were low. When those tendencies were allowed for no
excess mortality was found to have been associated with the mother’s
employment at home during the baby’s life.
The infants of mothers who were employed away from home, on
the other hand, had a death rate from all causes that was two and
one-half times as high as the average and a rate from gastric and
intestinal diseases that was over three times the average. This
excess mortality was associated with and partially explained by a
tendency toward early artificial feeding; but so far as this greater
prevalence of artificial feeding was a consequence of the employ
ment of the mother outside the home, the greater mortality due to
the unfavorable feeding should be charged against such employ
ment. The excess mortality was doubtless due in part also to the
overweighting of the group with babies whose mothers belonged to
nationalities which had high rates and especially with babies whose
fathers’ earnings were low- But even after allowances were made for
these factors there remained an excess in the mortality of this group
due probably to lack of the care which only the mothers who remained
at home could give. In short, the mother’s employment outside the
home— which, however, affected only one-twentieth of the months
under 1 year of age lived by all the babies in the study— seemed to
have been definitely associated with an increased hazard to the baby.
EARNINGS OF FATHER

The figures for father’s earnings used in the tabulations relate, as
already stated, to the amount earned by the father of the family
during the year immediately following the baby’s birth. This infor
mation was secured in most cases from the mother. The mothers
were asked not only as to the total amount but also as to wage
rates and periods of unemployment and sickness. If discrepancies
were found—-for example, if the time at work at the statea wages
would not have yieldea the total amount said to have been earned—
or if the mother could not give the information, the data were
secured later from the father.
If the father had died or had deserted during the year following
the child’s birth, the amount recorded was that which he actually
earned during that part of the year when he was contributing to the
support of the family. In sdme such cases the amount of the father’s
earnings which the family had to live on was much below his normal
earnings for a full year. In cases in which the father had died or
deserted prior to the birth of the child, he was classified as havin
“ no earnings.” The cases included in these two groups were not
numerous, but they are mentioned in order to emphasize the fact
that the reports of earnings were not, and should not be interpreted
as, statements of yearly wage rates.

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147

In most of the cities studied the statements of earnings thus
secured were not compared with pay-roll data, nor was information
obtained from employers. In the city of Manchester, however,
where a very large proportion of the fathers of infants included in
the study were employed in the textile mills, the mothers’ statements
as to fathers’ earnings were compared with the amounts as shown
on the pay rolls. For this city it was found that, when the births
and deaths were classified according to fathers’ earnings as stated
by the mothers, the results were substantially the same as when
they were classified according to amounts shown by the pay rolls;
on the whole, however, the statements of the mothers tended to
exaggerate slightly the amounts received.5
Besides data on the father’s earnings, information was secured as
to the amounts earned by the mother and by other members of the
family and as to other sources of income. The information obtained
on these points, however, was not considered so reliable as that on
father’s earnings. The earnings of mothers, for example, were
derived largely from keeping lodgers and boarders, and when this was
the source it was difficult to separate the net from the gross receipts.
In determining total family income, moreover, not only were net
receipts difficult to secure in some cases— for example, of income from
rents of houses owned but not lived in by the families— but also per
plexing questions arose as to whether a given item— for example,
money borrowed or money returned— constituted true income.
Futhermore, difficulties in comparing incomes arose from the fact
that some families had invested their savings in the homes occupied
by them and, though neither receiving nor paying rent, had incurred
various expenses connected with such ownership, and others had
invested their savings in such a way as to secure a definite cash
income. For the purposes of this study the amount which it would
have been most desirable to know was the portion of the income spent
for the maintenance of the family, or, better still, the portion actually
expended for the infant’s maintenance and in ways that would
influence the infant’s health, including expenditures for the health
of the mother. Since, however, this amount could not be ascer
tained and even the total family income was subject to much doubt,
the data on father’s earnings appeared to furnish the nearest approxi
mation to a satisfactory measure of the effect of economic status on
infant mortality. These data, therefore, -have been used as the
principal basis of classification, though the correlations of father’s
earnings, total income, and father’s earnings per capita of the family
with certain details of care of the infant and of the mother’s prenatal
and confinement care are pointed out in the course of the discussion.
All these data relating to amounts of earnings, it should be em
phasized, were secured before the marked rise in prices and wages
during and following the war. Since the time from the first to the
last study of the series was relatively short (about three years) the
figures for annual earnings in the different cities, so far as changes in
the level of prices and wages is concerned, may be considered fairly
comparable.
s* Classifying the births and deaths according to the earnings of the
father during the year immediately following the birth, Table 134
5
Since the material is used simply to show the correlation between earnings and mortality, a uniform
error of overstatement would not affect the validity of the conclusion.

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shows a marked relationship between infant mortality and father’s
earnings. The higher the earnings the smaller was the proportion
of deaths. For infants whose fathers earned less than $450 the rate
was 166.9, as compared with only 59.1 for those whose fathers earned
$1,250 or over. The group of babies whose fathers were classified
as having “ no earnings” had the highest rate of all (210.9).
T able 134.— Infant mortality rates, by cause o f death and earnings o f father; live
births in seven cities
Infant mortality rates 1
Epi
demic
Gastric
and
Respi Early other
and
Other
All
ratory infancy com causes
causes intesti diseases
nal
muni
diseases
cable
diseases

Neo
natal
mor
tality
rates 8

Live
births

Infant
deaths

Total............................. 21,536

2,368

1 1 0 .0

32.3

19.2

35.9

6 .8

15.7

44.4

3,085
2,827
2,908
5,050
3,345
1,391
2,252
313
365

515
355
339
543
277
89
133

166.9
125.6
116.6
107.5
82.8
64.0
59.1
210.9
139.7

60.6
44.9
36.5
27.1
19.7

33.4
23.3
18.9
19.6
13.5
7.9

43.8
35.4
37.5
37.4
30.2
25.9
32.4
41.5
49.3

12.3
6.4
9.3
5.5
4.2
3.6

16.9
15.6
14.4
17.8
15.2
18.0

2 .2

1 0 .2

16.0
16.4

19.2
16.4

55.8
46.0
43.3
46.5
38.0
33.1
38.2
60.7
41.1

Earnings of father

Less than $450_____________
$450-$549.................................
$550-$649.................................
$650-$849...............................
$850-$l. 049.........................—
$1,050-$1,249...........................
$1,250 and over.......................
No earnings______________ Not reported..........................

i Deaths under 1 year per 1,000 live births.

8 .6
8 .0

86.3
41.1
2

6 .2

47.9
16.4

Deaths under 1 month per 1,000 live births.

The distribution of births in the several father’s earnings groups
is shown also in Table 134. A striking fact was the small propor
tion— only 10.5 per cent— of the infants studied who were born in
families in which the father earned $1,250 or more. On the other
hand, 41 per cent were born in families in which the father earned
less than $650.
Additional income.

In practice the father’s earnings, except perhaps in the compara
tively small group in which they exceeded $1,250, constituted in
the vast majority of cases by far the largest part of the family’s
income and in fact may be said to have determined its economic
status. In Baltimore, for example, only 7 per cent of the families
had any income from insurance, investments, or rents from tenants
outside their own dwellings; the proportion having such income
was greatest, as would be expected, for families which on the basis
of father’s earnings were classed in the “ $1,250 and over” income
group.6 In a considerable proportion (23 per cent) of the families
in this city the earnings of the father were supplemented by those
of the motner or the children, but the amounts o f these supplementary
(earnings were small. In about half the cases the mother’s gross
earnings were less than $150. (See General Table 90, p. 229.) The
amounts reported for the children were on an average higher; in
about hajf the cases the total earnings of all the children in thev
family who worked amounted to $300 or over. (See General Table
6
See Infant Mortality—Results of a Field Study in Baltimore, M d., based on births in one year, by
Anna Rochester, p. 35 (U. S. Children’s Bureau Publication No. 119, Washington, 1923).

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E C O N O M IC FACT'OBS

91, p. 229.) I f the classification had been based on family income
instead of father’s earnings about one-fifth of the entire number
of infants would have been placed in higher groups, but the other
four-fifths would have been placed in the same groups by either
method. (See General Table 92, p. 230.)
Classifying the births both b y father’s earnings and by total
family income indicated, surprising as it may appear, that in families
with equal incomes from father’s earnings the infant mortality rate
was higher the more was contributed to the income from other
sources— in the majority of cases, the earnings of the mother or of
older children. (See General Table 92, p. 230.) This is doubtless
explained in part by the influence of the mother’s employment in
increasing infant mortality and in part by such factors as high order
of birth for infants in families which had children old enough to be
employed.
Earnings per capita o f fam ily.

The significance of father’s earnings as indicating economic pres
sure is shown in Table 135, which sets forth the correlation between
the amounts of these earnings and their distribution per capita of the
family. The estimated median per capita income from father’s earn
ings increased from $101 for the group “ under $450” to $338 for the
group “ $1,050 to $1,249.” 7
Since the average number in the family was slightly greater for the
lower than for the higher father’s earnings groups, the variation in
economic pressure appeared slightly greater than the variations in
the earnings themselves. In other words, as the father’s earnings
decreased the economic pressure increased at a slightly more rapid
rate. In general the lower the earnings the greater was the eco
nomic pressure as indicated by their distribution per capita.
T able 135.— Proportion o f births in fam ilies with per capita income from father's
earnings o f less than $100, and median earnings per capita, by earnings o f father;
live births in seven cities a
Live births—

Earnings of father
Total

In families with Median
per capita inper
come of less
capita
than $ 1 0 0 6
income b
Number Per cent

Total__

18,587

« 3,175

17.1

Less than $450.
$450-$549_.......
$550-$649.........
$650-$849-.......
$850-$1,049___
$1,050-$!,249__

3,077
2,826
2,905
5,047
3,341
1,391

1,508
853
513
256
43

49.0
30.2
17.7
5.1
1.3

$177
101

129
161
234
265
338

° For basic figures see General Table 93, p. 230.
b From earnings of father only.
c Excluding births in families in which fathers earned nothing or $1,250 and over, and those for which
warnings or number in family were not reported.
7
For this calculation the group ‘ ‘ $1,250 and over” was not considered; for the rest the father’s earnings
in each family were assumed to be equal to the middle point in the group in which the family was classed—
$500 for the families in the group $450 to $549, $600 for the group $550 to $649, etc.—and the per capita in
come was found by dividing by the number o f members reported for each family. For the group ‘ ‘under
$450” an arbitrary sum of $400 was set as the approximate average earnings for purposes of this calculation.

96515°—25f----- 11

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IN F A N T M O R T A L IT Y

Though the differences between father’s earnings groups may
therefore be taken as indicating differences in average per capita
income or in average economic pressure, in each of these groups were
included some families that would have been placed in a relatively
higher, and others that would have been placed in a relatively lower,
position on a per capita income scale than on the father’s earnings scale. /
If the families were all classified, therefore, on a per capita income
scale the true influence of economic pressure as a factor in infant
mortality would be more clearly presented.
In Table 136 the result of a classification by per capita income from
father’s earnings is presented for all the infants born in families in which
the father earned less than $1,250; that is, for those groups in which
the father’s earnings most closely represented family income. The
relationship shown Dy this grouping between economic pressure and
the infant mortality rate was even more striking— as indeed would
be expected— than that shown when no account was taken of the
number of members in the family. The conclusion seems justified,
therefore, that an analysis based on father’s earnings alone yields
substantially the same results as an analysis based on father’s earnings
per capita of his household and in fact gives trustworthy evidence as
to the relation of economic need to mortality among the infants
studied. The following discussion, therefore, is in terms of father’s
earnings, except where the number in the family has to be taken
into consideration as one of the items of the analysis.
T

able

1 3 6 .—

Infant mortality rates, by per capita income as measured by average
earnings of father per capita of household ,* live births in seven cities

Per capita income from father’s earnings

Live
births

21,536

2,368

1 1 0 .0

227
2,948
6,900

49
418
850
769
31

215.9
141.8
123.2
96.1
60.5

8 ,0 0 0

512
Not classified:
_
,
. ,
,
...
Father’s earnings less than $1,250—number in family not reported

Infant
mortality
rates1

Infant
deaths

19
2,252
313
365

133
66

59.1
210.9
139.7

Not shown where base is less than 100.
a including also a few cases in which the infant was In an institution.
1

Causes o f death o f infant.8

Not only did the general rate of infant mortality decrease as the
earnings of the fathers increased, but with one or two exceptions the
rates from the several causes, exhibited the same tendency as Table
133 shows. The mortality from gastric and intestinal diseases showed
perhaps the most marked variation b y earnings, the rate in the lowestearnings group uunder $450** being seven and. one-half times that
in the highest (“ $1,250 and over” ).9
* For classification by cause of death and per capita income from father’s earnings see General Table 94,
P'»2But not even in the highest-earnings group did the mortality from these causes approach the low rate
of 4.9 prevailing in New Zealand in 1915.

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FACTORS

The mortality from respiratory diseases likewise showed a marked
negative correlation with father’s earnings. For the infants of fathers
who earned less than $450 the rate was 33.4, as compared with 6.2
(less than one-fifth as high) for those of fathers who earned $1,250
and over. As would he expected, the mortality among the babies
whose fathers were reported to have had no earnings was highest of
all.
From epidemic diseases the lowest mortality was found to have been
in the father’s earnings group “ $1,250 and over” and the highest
in the two groups “ no earnings” and “ under $450.” Likewise from
causes peculiar to early infancy the rates were higher for the infants
of fathers who had the lowest earnings than for those of fathers who
earned $850 and over.
Neonatal m ortality.

The neonatal mortality rate (deaths in the first month per 1,000
live births) showed, according to Table 137, the same marked cor
relation with father’s earnings. This rate was 60.7 in the “ no
earnings” group and 55.8 in the group “ under $450,” but only 33.1
for the infants of fathers who earned $1,050 to $1,249. It was
s lig h t ly higher (38.2) in the group “ $1,250 and over.” 10
T

able

137 .— Neonatal mortality rates, by earnings of father; live births in seven

cities

Earnings of father

Total
live
births

Deaths Neonatal
mortality
under
1 month
rates

21,536
Less than $450____
$45ft-$549
$550-$649

$650-$849_________

3,085
2,827
2,908
5,050

Earnings of father

956

44.4

$850-$l,049________

172
130
126
235

55.8
46.0
43.3
46.5

$1,250 and over____
No earnings______
Not reported______

Total
live
births
3,345
1,301
2,252
313
365

Deaths Neonatal
under mortality
month
rates

127
46
86

19
15

','38.0
33.1
38.2
60.7
41.1

Plural births, prematurity, and death o f mother.

No significant differences appeared between the several earnings
groups in the occurrence of plural births. (See General Table 96,
p. 232.) According to Table 138, the proportion of premature births
was slightly larger for the group “ $1,250 and over” than for any
of the others except the “ no earnings” group. A slight correlation
was found between low earnings and a high death rate of mothers
during the year after confinement, the proportion of such deaths
being 6.6 per 1,000 for the “ less than $850” group as compared with
4 for that “ $850 and over.” (See General Table 97, p. 232.) All
these differences were comparatively slight, and in part they offset
each other; they did not, therefore, play any significant part in the
marked correlation between economic pressure and the infant mor
tality rate.
io See General Table 95, p. 231, for rates in other months.

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T a b l e 138 .— Proportion o f premature births, by earnings of father; live births in

eight cities
Live births

Live births
Earnings of father

Premature

Earnings of father

Premature
Total

Total
Number
21,536
$450-$549_________
$550-$649 _
$650-$849................

1 ,1 1 1

3,085
2,827
2,908
5,050

144
124
141
259

Per cent

Number

Per cent

5.2

$850-$l,049-............

3,345

180

5.4

4.7
4.4
4.8
5.1

$1,250 and over____
No earnings______
Not reported....... ..

2,252
313
365

138
26

6 .1

8.3
5.8

Age of mother, order o f birth, interval since preceding birth, and interval
before succeeding pregnancy.

Low economic status was found, according to Tables 139, 140, and
141, to be correlated with each of the four factors associated with
birth frequency. The low-earnings groups included a dispropor
tionate number of infants of orders fifth and later; of those born to
mothers under 20, or 35 years of age and over; of those born at short
intervals after preceding births; and of those 'whose mothers became
pregnant during the infants’ first year of life— all four divisions
which had higher than average mortality rates. In no case, however,
was there any very great difference between earnings groups in the
proportions of births in these' four divisions. The percentages of
infants born to mothers under 20, or 35 years of age or over, varied
only from 30.7 for those whose fathers were classified as having had
no earnings to 20.1 for those whose fathers earned $850 to $1,049.
For short-interval births the percentages varied from 29.4 in the
group “ under $450” to 20.4 in that “ $1,250 and over.” For infants
whose mothers became pregnant during the infants’ first year of life
the proportion varied from 16.2 per cent in the group “ under $450”
to 7.9 per cent in that “ $1,250 and over.” 11
T a b l e 139 .— Proportion of births to mothers under 20 and to those 35 years o f age

and over, and o f births fifth and later in order, by earnings o f father; live births in
seven cities a
Live birthsEarnings of father
Total

T o mothers under
20, and 35 and
over

Fifth and later in

Number Per cent Number

Per cent

Total...................... ........... .................................

21,536

4,895

22.7

5,530

25.7

Less than $450.............. ................................ ................
$450-$549_________ _____ _________________________
$550-$649 ____________ _________________________
$650-$849 ___ _____ ____ ________________________
$850-$l,049____________________ _____ ____________
$1,050-$l, 249_______________________ ____________
$1,250 and over. _______________________________
No earnings_________ _____ ______ ________________
Not reported-----------------------------------------------

3,085
2,827
2,908
5,050
3,345
1,391
2,252
313
365

849

27.5
24.3
23.8

1,064
853
810

2 0 .8
2 0 .1
2 1 .1
2 0 .8

1 ,2 1 2

34.5
30.2
27.9
24.0

688

692
1,051
673
293
469
96
84

30.7
23.0

697
283
408
92
111

2 0 .8

20.3
18.1
29,430.4

« For basic figures see General Tables 24 and 32, pp. 196 and 199.
11 In the “ no earnings” group, including families in which the father died or deserted before the infant’s
birth or was sick or unemployed during the entire year, only 1.4 per cent of the mothers became pregnant
during the infant’s first year.

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T

able

1 4 0 .—

Proportion o f short-interval girths,1 by earnings o f father; live births
in Baltimore 2
Live births second and later
in order—

Earnings of father
Total

Following preced
ing
births at
short intervals1
Number

Total.............

7,929

2,072

26.1

1,228
1,124

361
316
298
460

29.4
28.1
27.1
26.9

able

1 ,1 0 1

1,713

Following preced
ing births
at
short intervals1

Earnings of father
Total

Per cent

Less than $450 ___
$450-$549.................
$550-$649.................
$650-$849............
1

Live births second and later
in order—

For definition of interval see p. 60.

Number Per cent
$850-$l,049 ............
$1,050-$1,249_.........
$1,250 and over____
No earnings_______
Not reported______

1,128
476
854
148
157

280
105
174
35
43

2 2 .1

20.4
23.6
27.4

For basic figures see General Table 38, p. 201.

Proportion of births to mothers who became pregnant during first
year o f infant’ s life, by earnings o f father; live births in Baltimore

1 4 1 .—

Live births-

Earnings of father
Total

Live births

T o mothers who
became pregnant
during first year
of infant’s life 1
Number

Earnings of father
Total

Per cent

T o mothers who
became pregnant
during first year
of infant’s life 1
Number Per cent

Total-----------

10,797

1,232

11.4

$850-$l, 049

1,595

142

Less than $450____
$450-$549_________
$550-$649_________
$650-$849_________

1,544
1,449
1,489
2; 417

250
195
190
268

16.2
13. 5

$1,250 and over____

1 ,2 2 1

248

1 2 .8
1 1 .1

207
214

9.0
7.9
15.0

Omitting cases of infants who died in the same month in which mother became pregnant.

The most marked variations were found between the percentages
of births of orders fifth and later, which varied from 34.5 in the earn
ings group “ under $450” to only 18.1 in that “ $1,250 and over.”
Not only were these differences comparatively small, but to a
certain extent the four factors, order of birth, age of mother, interval
since preceding birth, and interval before succeeding pregnancy,
were interrelated. Births of high orders were commonly to older
mothers and were frequently associated with short intervals.
Eliminating the influence of age of mother and order of birth, as
Table 142 shows, did not alter materially the marked correlation
between low father’s earnings and a high infant mortality rate.
Similarly, when the influence of interval since the preceding birth
was eliminated, the relative mortality in the several earnings groups
was not materially altered. The rate for the “ no earnings” group
appeared relatively higher and that for the group “ under $450”
relatively slightly lower, while most of the other rates appeared not to
be significantly affected. No correction was attempted for interval
before succeeding pregnancy, since the proportion of the months lived
by all infants which were lived after the commencement of a succeed
ing pregnancy was so small that this factor could not have exerted any
appreciable influence (p. 67).

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1 4 2 . — Relative infant mortality, by earnings o f father, when influence o f age
o f mother and order o f birth, and influence o f interval since preceding birth, are
eliminated; seven cities and Baltim ore 1

able

Ratio of actual to expected deaths (per cent)
Seven cities
Earnings of father
Expected
at average
rates for
single
births

Total________________________________________
Less than $450. ____________ ____ _______ ___________
$450-$549....... .................................................................. .
$550-$649___________ _________________ _______ _____ _
$650-$849....... ................ ........... ........... .............. .............$850-$1,049................... ......... ........... ........................ ........
$1,050-$1,249— ....... ............................... ......................
$1,250 and over------- ------ ---------- ------ ----------------------No earnings....... ...... ......... ......................................... .
Not reported............................ ........................................
1

Baltimore

Expected
at rates
for same
order-ofbirth and
age-ofmother
group

Expected
at average
rates for
all births

Expected
at rates
for births
at same
interval
since
preceding
birth

1 0 0 .0

152.8
113.5
103.0
98.0
'/5. 4
59.0
54.5

142.5
108.8

151.4
114.0
105.1
92.8
69.1
64.3
62.5
200.7
135.5

140.3
116.9
100.5
96.5

2 0 0 .0

130.1

1 0 1 .1

98.8
78.1
61.9
59.6
191.6
128.6

6 6 .1

66.9
60.8
211.4
131.1

For basic figures see General Table 98, p. 232.

With reference to order of birth, which is closely related to the
number in the family, the father’s earnings seem especially inappro
priate as an index of economic pressure. Accordingly, for this corre
lation an analysis is made in Table 143 to show the relative mor
tality in the groups With varying economic pressure after the influence
of order of birth is eliminated. A study of this table shows that even
after the elimination of order of birth as a factor the mortality in the
group with the smallest per capita income from father’s earnings,
“ less than $50,” was over twice as high as in the group with the
largest per capita income, “ $400 and over.”
T

able

1 4 3 .—

Relative mortality, by economic needfwhen influence of order o f birth
is eliminated; live births in seven cities
Infant deaths

Per capita income from father’s earnings
Actual

2,117
$50-$99.....................................................................*............................... ......
$100-$199 - ............... .................................................................. - ................ $200-$399
....... .........................................................................................

49
418
850
769
31

Ratio of
to
Expected2 actual
expected
(per cent)
2,117.0
37. 5'
395. 9
785. 0
843. 8 54.8

1 0 0 .0

130.7
105. 6
108. 3
91.1
56.6

iAs measured by the average amount of father’s earnings per capita of family.
* Expected at average rate for each order of birth irrespective of per capita income from father’s earn
ings.
M

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Type of feeding .12

An answer to the question as to whether the high mortality rate
among infants of fathers whose earnings were low was due to an
unusual prevalence of artificial feeding is given in Table 144. This
table shows that, on the contrary, exclusively artificial feeding was
less prevalent in the low than in the high earnings groups; of the
months lived from birth to the end of the ninth by babies whose
fathers earned less than $450, 22 per cent were months of artificial
feeding, as compared with 30 per cent of those lived by babies whose
fathers earned $1,250 and over. The variations in the prevalence of
exclusively breast feeding were slight, the group “ $850 to $1,049 ” hav
ing the largest percentage (58.6) and the highest-earnings group
having the smallest (55.3) except that of the “ no earnings” group,
in which many mothers went out to work (46.8). The variations
in the prevalence of partially breast feeding were more marked;
the “ no earnings” group had the highest proportion (21.7 per cent),
and the group “ $1,050 to $1,249” had the lowest (14.2 per cent).
Since the disadvantages associated with the use of artificial food are
much greater when it is used exclusively than when it is used only to
supplement the mother’s milk, it is evident that the babies in the
lower-earnings groups had more favorable feeding than those in the
higher. The excessive mortality in the former occurred in spite of a
smaller proportion of infants who were artificially fed. A correction
for the varying prevalence of artificial feeding, therefore, would tend
to increase the relatively high mortality associated with low earnings.
T

able

1 4 4 .—

Prevalence o f exclusively artificial feeding, by earnings o f father;
months lived from birth to end of ninth; infants in seven cities 1
Per cent of months lived from
birth to end of ninth

Earnings of father
Breast
fed

Partly
breast
fed

Arti
ficially
fed

Per cent of months lived from
birth to end of ninth
Earnings of father
Breast
fed

Partly
breast
fed

Arti
ficially
fed

Total_______

57.0

17.4

25.6

$850-$l,049...............

58.6

14.9

26.4

Less than $450$450-$549-......... ......
$550-$649___
$650-$849.................

56.7
57.2
57.0
57.8

2 1 .1

2 2 .0

21.3
18.3
16.1

21.5
24.7
26.1

$1,250 and over.......

55.3
46. 8
50.3

14.7
21 .7
18.5

30.0
31. 5
31.0

For basic figures see General Table 100, p. 234.

The relative mortality b y father’s earnings is shown in Table 145
for breast-fed, partly breast-fed, and artificially-fed infants sepa
rately. The greatest contrast was found among the artificially fed;
the death rate for babies thus fed whose fathers earned less than
$450 was over five times that for such babies whose fathers earned
$1,250 and over. Among the breast-fed babies, on the other hand,
the rate for the lowest was slightly over three times that for the
highest earnings group. In each type-of-feeding group a marked
^correlation was found between low earnings and nigh mortality.
w See General Tables 99, 100, and 101, pp. 233,234,235,

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T a b l e 145 .— Relative mortality, by earnings o f father, among breast-fed, partly

breast-fed, and artificially-fed infants in seven cities
Deaths among—

Earnings of father

Breast-fed infants
Ratio
.Actual Expect
(per
ed 1
cent)

Partly breast-fed infants

Artificially-fed infants

Ratio
Actual Expect
(per
ed 1
cent)

Ratio
Actual Expect
(per
ed i
cent)

Total................... .........

600

599.7

1 0 0 .0

246

245.7

1 0 0 .0

1 ,0 0 2

1 , 0 0 1 .5

1 0 0 .0

Less than $450...........! .___
$450—
$549________________
$550-$649 ___________
$650-$849_ _______________
$850-$1,049___________
$1,050-$1,249..... ..................
$1,250 and over_________ _
No earnings...... ...................
Not reported..................... .

142
84
78
162
60
23
31

84.8
79.3
81.4
141.9
95.5
38.7
61.8
7.2
9.1

167.5
105.9
95.8
114.2
62.8
59.4
50.2
138.9
109.9

69
42
43
42

40.7
42.4
31.1
53.0
33.4
13.8

169.5
99.1
138.3
79.2
62.9
36.2
30.7
214.3
186.0

220

120.4

182.7
146.1
117.2
91.3
71.7
42.7
33.6
217.1
101.4

1 Expected

10
10

5
7
9
8

2 2 .8

4.2
4.3

161
152
• 219
117
32
42
38
21

1 1 0 .2

129.7
239.9
163.1
74.9
125.1
17.5
20.7

at average rates in each month for all infants receiving specified type of feeding.

Color and nationality o f mother.

A marked correlation between low earnings and a large proportion
of births to mothers of nationalities for which the infant mortality
rates were high appears in Table 146. Of the babies whose fathers
earned less than $450, 55 per cent as compared with only 10 per cent
of those whose fathers earned $1,250 or over, were born to mothers
who belonged to nationalities which had high infant death rates.
This close correlation suggests the importance of ascertaining to
what extent the high mortality in the low-earnings groups may have
been due to the association o f low earnings with nationalities which
had high rates.
That this correlation with nationalities which had high infant
mortality rates accoimted for but a relatively small part of the
excess mortality associated with low earnings is apparent from Table
147. In each of the principal color and nativity groups, the native
white, the foreign-born white, and the colored, the relation between
low earnings and high infant mortality was striking. And among
the native white infants alone— a group uninfluenced by apy dispro
portionate weighting with colored or with foreign nationalities— the
relation between mortality and father’s earnings was even more
striking than in the entire group studied. Furthermore, the dif
ferences between the average mfant mortality rates of the three race
and nativity groups appeared to have resulted largely from the un
favorable weighting of the foreign-born white and the colored with
disproportionate numbers of infants in the low-earnings groups; for
the differences between the rates for the infants of the foreign-born
and colored mothers were relatively slight when comparisons were
made of groups in which earnings were substantially equal. The
high rate of 166.9 in the earnings group “ under $450,” for example,
was not increased by the inclusion of a disproportionate number of
infants of colored mothers; in fact, in this particular earnings group~
the rate for such infants was not so high as that for the infants of
native white mothers. The conclusion may fairly be drawn, there-

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fore, that the relationship found between low father’s earnings and
high infant mortality was independent of the correlation between
low earnings and color and nationality.13
T a b l e 146 .— Nationality o f mother, by earnings o f father; live births in seven cities 1

Live births—

Earnings of father
Total

Live births—

T o mothers of na
tionalities with
high infant mor
tality rates. 2

Earnings of father
Total

To mothers of na
tionalities with
high infant mor
tality rates. 2

Number
T o ta l......... .
Less than $450____
$450-$549_______
$550-$649_____
3650-3849............

Per cent

21,536

6,904

32.1

3,085
2,827
2,908
5,050

1,697
1,362
1,046
' 1,450

55.0
48.2
36.0
28.7

Number Per cent
$850-31,049________
3l,050-$l,249____
$1,250 and over
No earnings
Not reported-.........

3,345
1,391
2,252 •
313
365

672
197
225
132
123

2 0 .1

14.2
1 0 .0

42.2
33.7

1 For basic figures see General Table 76, p. 221.
’ Including French-Canadian, Polish, Portuguese, “ other foreign bom ,” and colored.

T a b l e 147 .— Infant mortality rates, by color and nativity o f mother and earnings

o f father; live births in seven cities 1
Infant mortality rates
Color and nativity of mother

Earnings of father
Total

Native
white

Foreignborn white

Colored 2

Average-

1 1 0 .0

93.9

123.7

152.3

Less than $450.
$450-$549_____
$550-$649_....... .
$650-$849_____
3850-31,049____
$1,050-31,249__
$1,250 and over.
No earnings___
Not reported...

166.9
125.6
116.6
107.5
82.8
64.0
59.1
210.9
139.7

170.0

167.1
118.4

162.7
163.7

1
2

1 2 1 .0
1 1 0 .8

99.5
76.4
62.6
57.6
187.5
154.7

1 2 1 .8

119.6
94.9
68.4
60.0
234.2
129.5

1 2 2 .8

102.7

For basic figures see General Table 102, p. 236.
Not shown where base is less than 100.

Housing congestion.

A striking correlation was found, as Table 148 shows, between
low income and housing congestion. Of the infants who survived
for at least two weeks 77.2 per cent of those whose fathers earned
less than $450, as compared with only 17.5 per cent of those whose
fathers earned $1,250 and over, were found in families which lived
one or more persons per room.
When allowance was made in Table 149 for this correlation, the
ncrease in the mortality as the father’s earnings fell appeared quite
as striking as before the correction was made.
13 A separate analysis of the rates by nationality of the foreign-born group leads to a similar conclusionnamely, that the relationship between low earnings and high infant mortality rates was, on the average,
practically as marked within each nationality group as in the group as a whole.

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T a b l e 148 .— Prevalence o f overcrowding, by earnings of father; infants in seven

cities 1
Infants surviving two weeks—

Infants surviving two weeks—
In families living 1
or more persons
per room.

Earnings of father
Total

Number

Per cent

Total_______

20,698

9,730

47.0

Less than $450____
$450-$549.................
$550-$649_________
$650-849................. .

2,943
2,719
2,799
4,856

*2,124
1,702
1,589
2,189

72.2
62.6
56.8
45.1

In families living 1
or more persons
per room.

Earnings of father
Total

Number
$850-$l,049..............
$1,050-$1,249........
$1,250 and over____
No earnings______
Not reported______

3,229
1,347
2,173
291
341

Per cent

1,038
353
381
190
164

32.1
26.2
17.5
65.3
48.1

For basic figure see General Table 80, p. 224.

T a b l e 149 .— Relative mortality, by earnings o f father, when influence o f housing

congestion is eliminated; infants in seven cities surviving two weeks 1
Infant deaths

Infant deaths
Ratio of
actual to
expected
(per cent)

1,566

1,566.4

1 0 0 .0

$850-$l,049--...........

378
249
234
352

269.9
228.9
226.1
355. 9

140.1
108.8
103.5
98.9

$1,250 and over____
No earnings______
Not reported..........

Actual

$èk)-$849.................

Earnings of father

Ex
pected 2

Earnings of father

Actual

$1 OhO-$1,249

163
49
57
50
34

Ratio of
Ex
actual to
pected 2 expected
-(per cent)
216.8
86. 5
130.8
25. 5
26.0

75.2
56.6
43.6
196.1
130.8

i Excluding a small number of infants who did not live two weeks in dwelling of residence (Baltimore).
a Expected if in each group classified by earnings of father and number of persons per room the average
rate in the corresponding persons per room group had prevailed.

Employment o f mother during pregnancy.

The evidence presented in Table 150 shows that a close relationship
existed between low earnings of the father and employment of the
mother. The proportion of mothers employed away from home
during pregnancy was highest— 37.4 per cent— in the “ no earnings”
group, was 28.3 per cent in the group tc under $450,” and was lowest—
1.9 per cent— in the group “ $1,250 and over.” The high mortality
in the low-earnings groups was slightly increased, therefore, by the
high mortality among the babies of mothers who worked away from
home.
That this effect, however, was not great is clear from Table 151,
which shows that the mortality in the low-income groups was rela
tively almost as high, as compared with that in the high-income
groups, among infants of mothers who were not employed as among
those of mothers who were employed away from home, though in all
earnings groups the former had lower rates than the latter.

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T a b l e 150 .— Prevalence o f employment of mothers during pregnancy, by earnings

o f father; live births in seven cities
Live birthsTo mothers employed during pregnancy—
Earnings of father
Total

Total
Number

At home •

Per cent Number

Away from home

Per cent Number

T otal........... .....................

21,536

6,606

30.7

3,535

16.4

3,071

Less than $450............ ..........
$450-$549___________ ____
$550-$649____________________
$850-$849______________
$850-$l, 049_________________
$1,050-11,249______________
$1,250 and over...........................
No earnings______________
Not reported........... ................ __

3,085
2,827
2,908
5,050
3,345
1,391
2,252
313
365

1,637
1,248
995
1,265
661
207
264
176
153

53.1
44.1
34.2
25.0
19.8
14.9
11.7
56.2
41.9

765
599
466
718
459
165

24.8

872
649
529
547

221

59
83

2 1 .2

16.0
14.2
13.7
11 . 9
9.8
18.8
22.7

Per cent
14.3
28.3
23.0
18.2

202

1 0 .8
6 .0

42
43
117
70

3.0
1.9
37.4
19.2

T a b l e 151 .— Infant mortality rates, by mother’s employment during pregnancy and

earnings o f father; live births in seven cities
Mothers employed during
pregnancy

Mothers not employed during
pregnancy

Earnings of father
Live
births
Total

_________________

Less than $450.______ __________________
$450-$549....... ........................ .........
$550-$649............................
$650-$849______________________
$850-$l,049____ ________
$1,050-$1,249______
$1,250 and over....... ..............
No earnings__ t ______
Not reported________ . . .

Infant
deaths

Infant
mortality
rates

Live
births

Infant
deaths

Infant
mortality
rates

6,606

926

140.2

14,930

1,442

96.6

1,637
1,248
995
1,265
661
207
264
176
153

303
168
137
145
75
19

185.1
134.6
137.7
114.6
113.5
91.8
75.8
215. 9
137.3

1,448
1,579
1,913
3,785
2,684
1,184
1,988
137

212

146.4
118. 4
105.6
105. 2
75.3
59.1
56.8
204.4
141.5

38
21

212

187
202

398
202

70
113
28
30

The responsibility of low father’s earnings, apart from that of
customs and traditions associated with nationality, for the employ
ment of the mother is shown in Table 152.13 This table indicates
clearly, as would be expected, that low earnings of the father must be
considered to have been a primary factor in causing the mother to
seek employment away from home.
13 For the influence of such customs and traditions apart from that of low father’s earnings see discussion,
pp. 117 and 119.
*

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1 5 2 . — Prevalence o f mother’s employment away from home during pregnancy,
by earnings o f father, when influence o f nationality o f mother as a factor in mother’ s
employment is eliminated; live births in seven cities

able

Live births to mothers em
ployed away from home
during pregnancy

Live births to mothers em
ployed away from home
during pregnancy
Earnings of father

Earnings of father
Actual

$450-$549_________
$550-$649___
$650-$849_________

Expect
ed»

3,071

3,071.4

872
649
529
547

659.3
536.1
440.6
637.1

Ratio of
actual to
expected,
(per cent)'
1 0 0 .0

132. 3
1 2 1 .1
1 2 0 .1

85.9

Actual

$850-$l,049.... ..........

Ratio of
Expect actual to
ed»
expected
(per cent)

202

356.0

56.7

43
117
70

196.8
58.8
55.4

199.0
126.4

2 1 .8

1 Expected if the proportion of mothers employed away from home during pregnancy in each nationality
group were applied to the live-born infants classified by father’s earnings and mother’s nationality.

Employment o f mother during first year o f infant’s life.

In Table 153 the prevalence of employment of the mother during
some part of the first year of the infant’s life is shown to have varied
with the father’s earnings. The proportion of mothers employed
away from home was highest— 38 per cent—in the “ no earnings”
group, was 19.6 per cent in the group “ under $450,” and was lowest—
0.6 per centy-in the two groups “ $1,050 to $1,249” and “ $1,250 and
over.” As in the case of employment during pregnancy the higherearnings groups had very few mothers employed away from home;
and in each such« group a much smaller proportion of mothers were
found to haye been employed away from home during the infant’s
first year than were found to have been so employed during pregnancy.
Tne percentages of mothers who were employed at some time
during the infant’s first year of life, however, tend to overstate the
actual importance which such employment may have had as a factor
in the infant mortality rate (see also pp. 139-140), since a casein which
the mother resumed work at the eleventh month was counted in
the same way as was one in which she resumed work at the third,
though obviously the possible influence upon the health of the child
was much greater in the latter than in the former case. Of the total
number of months lived by infants in the several earnings groups
the proportion lived by babies after their mothers went to work
away from home varied from 12.1 per cent in the group “ under $450 ”
to 0.4 per cent in the group “ $1,250 and over.” In fact, in view of
the small proportion of the first year of life lived b y infants while
their mothers were employed away from home, the correction for
such employment appeared to be of comparatively minor importance.
The high mortality found among the infants in the low-earnings
groups must have been due not only to a high mortality among the
babies whose mothers were employed but also to a high mortality
among those whose mothers were not employed,

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T

1 5 3 . — Prevalence o f mother’s employment at home and away from home
during first year o f infant’s life, by earnings of father; infants in seven cities

able

Live births—
To mothers employed at some time during first year of
infant’s life—
Earnings of father
Total

Total

At home

Number Per cent Number
Total__________________
Less than $450.............................
$450-$549_____________________
$550-$649................ ................... .
$650-$849.....................................
$850-$l,049.,..._______________
$1,050-$1,249__________________
$1,250 and over___ ______ ____ _
No earnings...............................
N ot reported.... ........... ............ .

Away from home

Per cent Number

21,536

5,821

27.0

4,091

19.0

1,730

3,085
2,827
2,908
5,050
3,345
1,391
2,252
313
365

1,506
1,080
803
1,088
567
196
247
192
142

48.8
38.2
27.6
21.5
17.0
14.1

900
692
549
854
516
187
233
73
87

29.2
24.5
18.9
16.9
15.4
13.4
10.3
23.3
23.8

606
388
254
234
51
9
14
119
55

1 1 .0

61.3
38.9

Per cent
8 .0

19.6
13.7
8.7
4.6
1.5
.6
.6

38.0
15.1

Table 154 shows the importance of low earnings of the father as
a factor in causing the mother to seek employment outside the home
during the infant’s first year of life after the influence of customs and
traditions associated with nationality was eliminated. Though in
every earnings group thé mothers appeared to have sought work
away from home less frequently during the infant’s first year of life
than during pregnancy, the variations between the proportions in
the several earnings groups seemed more marked than in the case of
the mother’s employment during pregnancy. Apparently the need
of additional income must have had to be greater for the mothers
to seek work during the life of the baby than for them to seek it
during pregnancy, a fact which may perhaps be explained by the
care and attention required by the young baby.
T

1 5 4 . — Prevalence o f mother’s employment away from home during first year
o f infant’ s life, by earnings o f father, when influence o f nationality as a factor in
mother’s employment is eliminated; infants in seven cities

able

Live births to mothers em
ployed away from home
during first year of infant’s
life
Earnings of father
Actual

Ratio of
Expect actual to
ed 1
expected
(per cent)

Total___

1,730

1, 730. 4

1 0 0 .0

Less than $450.
$450-$549_____
$550-$649_.......
$650-$849_____
$850-$l,049.......
$1,050-$1,249—
$1,250 and over
o earnings__
Not reported..

606
388
254
234
51
9
14
119
55

403.6
320.9
246.9
338.8
183.2
66.4

150.1
120.9
102.9
69.1
27.8
13.6
13.9
320.4
168.6

1 0 0 .8

37.1
32.6

1 Expected if the proportions of mothers employed away from home during first year of infant’s life in
each nationality group were applied to the live-born infants classified by father’s earnings and mother’s
nationality.

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Chain o f causation linking earnings o f father and infant mortality.

The influence of the father’s earnings upon his infant’s chances of
life was exerted through the relation of the family’s economic status
to the mother’s health and care during pregnancy and confinement
and to thé care of the baby during his first year.
An intimate connection was found, as Table 155 shows, between
father’s earnings and the extent and quality of prenatal care in the
one city (Baltimore) for which information on these points was
secured. Thus 53 per cent of the mothers in the group “ under
$450” had no medical prenatal care as compared with only 13.8
per cent of those in the group “ $1,850 and over.” Of the mothers
in the lowest-earnings group 35.7 per cent were not attended by a
physician at confinement as compared with only 6.6 per cent of those
in the highest. Nursing care during the confinement period was
received by 37.2 per cent of the mothers in the lowest group as com
pared with only 7.5 per cent of those in the highest. And the pro
portion of mothers who stayed in bed or in a hospital for less than
seven days after delivery varied from 12.8 in the lowest to 1.7 per
cent in the" highest earnings group.
Though ignorance of the rules of health in the poorer families
doubtless played some part in producing these differences, the ob
vious relation between lack of means and failure to obtain medical
and nursing services and competent advice or to follow out that ad
vice suggests that lack of means, or economic pressure, must have
borne a heavy responsibility.
T

1 5 5 . — Medical and nursing care received by mothers of legitimate infants
during pregnancy and confinement, by earnings o f father; Baltimore, 1915

able

Earnings of father

Per cent of
Per cent of Per cent of mothers
mothers
mothers
not at
having
having no
by
prenatal tended
medical
physician
prenatal
care of
at
con
grade A 1
care
finement

cent of
Per cent of Per cent of Per
mothers
mothers
who
mothers
having 10 having no stayed in
or more
nursing
bed or in
visits
hospital
care dur
from
less
than
ing
con
physician
7 days
finement
after
after
period
delivery 2
delivery

______ ____ ___

47.5

5.1

32.6

15.6

28.6

Less than $450.... .....................
$450-$549..................................
$550-$649_____________ _____ $650-$849......................... ..........
$850-$l,049__ ____ ___________
$1,050-$1,249..............................
$1,250-$1,449.............................
$1,450-$1,849_______ ______ —
$1,850 and over.................... .
No earnings_________ _______
Not reported............ ................

53.0
58.7
59.8
52.7
40.5
30.0
32.9
21.3
13.8
41.4
39.7

1.3

35.7
43.6
43.7
36.6
27.9
18.1
19.1
8.5

8.9

37.2
30.1\
29.91
30.4
26.0
25.0
19.8

Total

1 .8
1 .6

3.5
6 .6
8 .2

9.2
16.4
30.3
1.7
4.2

6 .6
2 2 .0

25.1

8 .2

9.2
14.5
20.7
24.1
26.9
40.1
40.3
8 .2

15.7

7.5f
34.9
31.0

8 .1
1 2 .8
1 1 .8

7.1
4.2
3.4
2.4
17
7.3
7.3

1 To qualify as grade A care, the care received by the mother must have satisfied all four of the following
requirements: (1) Monthly visits to clinic, or supervision by private physician, from the fifth to the ninth
month of pregnancy; (2) monthly urinalysis from the fifth to the ninth month; (3) an abdominal ex
amination; and (4) pelvic measurements (if the mother was a primipara).
2 Exclusive of mothers with complications of confinement.

^The health program recommended by the best medical authorities
for pregnant women includes wholesome and nourishing food, at least
two hours daily in the open air, and freedom from worry and over
work. This program is obviously one which can be observed more
easily and faithfully by women in comfortable circumstances than by
women who have to struggle to make ends meet.

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163

When, furthermore, as in many of the families included in this
study, the meager earnings of the father have to be supplemented
through gainful employment of the mother during pregnancy, the
lack of adequate income from father’s earnings is primarily responsi
ble for the increased mortality which is found to 1be associated with
the mother’s employment during that period, (See discussion, pp.
158-160.)
Specific evidence in regard to the correlation between income and
the quality and quantity of care which the baby received during his
first year was difficult to secure and was limited to a few points, such
as feeding, housing congestion, and the gainful employment of the
mother.
A principal element of infant care, maternal nursing during the
first nine months, has already been discussed; artificial feeding was
less commonly practiced in the lower than in the higher earnings
groups. Specific evidence as to the quality of the artificial food used
by the several groups unfortunately is lacking.* The table already
presented (p. 102) indicates, however, that artificial feeding was
fraught with greater dangers to the baby’s health in the lower-earn
ings groups. Doubtless such feeding as practised in the families with
larger incomes was accompanied by safeguards that were not em
ployed to the same extent in the poorer families. These safeguards
probably included the use of pure milk, the practice of proper sterili
zation of bottles and nipples, the advice of a competent physician in
regard to a suitable milk-modification formula and his supervision
over the feeding of the baby, and the purchase and correct utilization
of the ingredients and medicines prescribed. Each of these safeguards
involves the expenditure, if not of money, at least of the mother’s
time; and therefore their use, other things being equal, would
naturally be intimately associated with the income available for the
care of the infant.
That differences in the safeguards surrounding the practice of
artificial feeding did not fully explain, however, the greater mortality
among the infants whose fathers’ earnings were comparatively low is
shown by the fact that a contrast similar to that between the rates
for the artificially fed was found between those for the breast-fed
babies in the several earnings groups. Factors explaining the lower
mortality among the babies whose fathers had higher earnings
doubtless included the greater availability of nursing and medical
services during the infant’s first year. An additional advantage to
the infants in the higher-income groups consisted in the fact that
their mothers were freer from household cares, either because of the
employment of servants or because of the use of mechanical aids to
work, and as a consequence had more time to care for their babies.
With larger incomes, moreover, went more satisfactory housing
accommodations, as evidenced by the lesser congestion of sleeping
and living quarters, and less employment of the mothers away from
home. So far as low father’s earnings were responsible for housing
congestion and for the mother’s gainful employment during the first
year of the infant’s life they were responsible for the greater mortality
associated with these factors.
Causes of low father’s earnings and of low per capita income.

The causes of low father’s earnings and of low per capita income
may be indicated in a general way. They depend in part upon the

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causes of low wage rates— the oversupply of labor of particular
grades and its relative unproductivity, either because of working
with insufficient tools or machinery or under antiquated methods, or
because of lack of training or of the capacity to acquire skill. They
depend also in part, upon unemployment and its causes—periodic
fluctuations in business ; variations in the demand for labor at a
particular establishment resulting in temporary expansions or in
lay-offs; difficulties incident to the settlement of wage disputes,
including strikes and lockouts; and the personal qualities of the
individual workman, including qualifications for the job, steadiness
at work, and satisfactory or unsatisfactory performance of duties.
They depend, furthermore, upon the causes of failure of the father
to contribute to the family support other than causes resulting in
unemployment, such as his sickness or death or his desertion of the
family. Finally, low per capita income, as distinguished from low
earnings, depends also upon the size of the family, including the
children and other dependents for whose maintenance the bread
winner may be obligated.
Even this partial enumeration of the causes of low income is suffi
cient to show the complexity of the subject. The solution of the
problems involved is a task for the future. Fortunately, however,
so far as the relationship between low income and infant mortality is
concerned, the fact that the connection is indirect makes possible
a method of breaking the chain, namely, making available to all
families the elements of care most important for the safeguarding of
the health of mother and baby.
Summary.

In the group studied (city births) a marked correlation was found
between low earnings of father and high infant mortality. The
analysis indicated further that low earnings corresponded to high
economic pressure as measured by the per capita income of the
family from the father’s earnings. The relationship between low
earnings and infant mortality was found to be independent of type
of feeding, of nationality, and of the factors involved in frequency of
births; furthermore, it was largely independent of housing conges
tion and of the mother’s employment, since the same tendency for
the rate to fall as the earnings increased was found among the fam
ilies living in uncongested as among those living in congested quar
ters and among the families in which the mother was not employed
as among those in which the mother was employed away from home.
The responsibility of low income for high infant death rates
extended beyond the mortality directly associated with it, cohering
much of that associated with housing congestion and with the
mother’s employment.
The study of the chain of causation connecting low income with
high mortality showed the direct relation between lack of means and
the care available both for the mother during pregnancy and confine
ment and for the baby during his first year. It suggested, therefore,
that if adequate care had been available for the mothers and babies iru
the low-income groups the high mortality rates of the babies in these
groups would not have been found.

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APPEN D IX A .— STILLBIRTH S

In order to eliminate, so far as possible, the influence of variations
in the definitions of stillbirths in use in the different States, only
cases of at least seven months’ gestation were included in this in
quiry. In each of the States in which the cities chosen for study
were located stillbirths were required by law to be registered, and in
each State the legal definition covered cases of at least seven months’
gestation.
In studying the question of stillbirth a policy of exclusion was
adopted similar to that employed in studying the mortality among
live-born infants. The exclusions, therefore, were of five classes:
(1) Illegitimate births, (2) births to nonresident mothers, (3) births
to mothers who were known to have moved away from the city,
(4) births to mothers who had moved away from their addresses as
given on the birth certificates and who could not be traced, and (5)
births for which the data secured were incomplete or seemed un
reliable.. The reasons for these exclusions were similar to those
given on page 12 for the exclusion of live-born infants of these classes;
the securing of a sound basis for stillbirth rates required that the
same policy of exclusions be applied to the numerator of the rate
fraction as was applied to the denominator.1
In all, 813 cases of stillbirth were included in the study, a figure
which, when compared with the total number of births, gives a still
birth rate 2 of 3.4 per cent. Satisfactory comparisons with rates for
other areas are difficult, owing to variations in the definition of still
birth. A tabulation of “ stillbirths registered as births” in the
greater part of the birth-registration area in 1918 made by the
Bureau of the Census indicated a rate of 3.8 per cent. In the census
tabulation, however, cases of less than 7 months’ gestation were also
included, so far as they had been registered as births.3
C AU SES O F STILLB IR TH

No satisfactory evidence was available with regard to the specific
causes of the stillbirths included in this study. Though spaces for
entering the causes of death in such cases were provided on the
death certificates, frequently no entry was made; and when entered,
the causes as a rule were described in terms so vague that they were
practically useless for purposes of analysis. In general, the causes
of stillbirth are similar to those of deaths in early infancy and have
their origin for the most part in the health and condition of the
mother and in the quality of the care that she receives during preg
nancy and at confinement.
See also Appendix B, p. 183, for number of stillbirths excluded.
*
Stillbirth rates are calculated as percentages of all births, including both live and still births. _
Compiled from Birth Statistics, 1918 (U. S. Bureau of the Census), pp. 28-29. The above rate is calcu
lated as a percentage of all births.
_
1
2
2

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P H YSIC A L C O N D IT IO N OP M O T H E R

It has already been mentioned in connection with the analysis of
infant mortality that available evidence concerning the mother’s
physical condition was limited to comparatively few points. These
included whether the mother died during the year following confine
ment, whether she had or had ever had tuberculosis, whether she had
convulsions during pregnancy or confinement, and whether she had
medical prenatal and confinement care.4
Death o f mother.

The percentage of stillbirths to mothers who died during the year
following confinement was 18.6, over five times as high as that of
such births to all other mothers (3.3). The rate was especially high
(32.5 per cent) for births to mothers who died within the following
month— almost all from causes directly connected with pregnancy or
confinement. In these cases probably the same causes that ,led to
the death of the mother were responsible for the death of the infant
at or before birth. For births to mothers who died after the first
month but during the year following confinement, the rate (based on
comparatively few cases) was 6 per cent, or nearly twice that for
births to mothers who survived the year.
In this connection it is of interest to note that the stillbirth rate
for infants who were prematurely born to mothers who died (26.3
er cent) was only slightly higher than that for other premature
irths (22.1 per cent). On the other hand, the stillbirth rate for
infants born at term to mothers who died (15.9 per cent) was over
seven times as high as that for full-term births to mothers who sur
vived the year (2.1 per cent). (Compare General Tables 4 and 7,
pp. 188 and 189.)

Tuberculosis o f m other.

The number of cases of stillbirths to mothers who had or had ever
had tuberculosis was too small to show any influence of this condi
tion upon the rate. Of 99 babies of such mothers 3 were born dead,
as compared with 3.56 stillbirths at the rate for all other births.
. Convulsions.

Of 53 cases in which mothers had convulsions as a complication of
pregnancy or confinement 11 resulted in stillbirths. The figure repre
senting stillbirths expected in this group at the rate for all other
births was 1.84. In other words, the stillbirth rate for the babies of
mothers who had convulsions was nearly six times that for other
infants.
M edical prenatal care.

The fact already pointed out as making difficult any conclusion in
regard to the relation between prenatal care and infant mortality was
strikingly illustrated by the stillbirth rate of mothers who had had
such care; namely, the 'greater tendency of mothers who were in poor
health than of those who were well to seek medical care during preg
nancy. The results of this tendency were shown clearly in the fact
that the stillbirth rate for cases in which the mothers had medical
>renatal care was 4.1 per cent, as compared with only 2.9 per cent
or those in which the mothers had no such care.

* The data on all these points except the death of the mother were limited to one city, Baltimore.

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A P P E N D IX A .— S T I L L B I R T H S

FR EQ U EN C Y OF B IR T H

Age o f mother.

The stillbirth rates, as Table 156 shows, varied with the age of the
mother, being relatively high for the babies both of mothers under
20 and of those 40 years of age and over. For the infants of mothers
who were under 18 the rate was 5.2 per cent, only slightly less than
that (5.6 per cent) for those of mothers who were 40 and over. When
the stillbirths in the age group “ 40 and over” were analyzed, it was
found that the rate for ages 40 to 44 was only 5.1 per cent and that
for ages 45 and over (based on very few cases) was more than three
times as high (15.4 per cent). The lowest proportion of stillbirths
was found m the group of births to mothers who were 20 to 24
years of age.
T

able

1 5 6 .—

StilWirth rates, by age of mother; births in eight cities
Stillbirths

Stillbirths
Age of mother

Births

Age of mother

Number

Per cent

23,780

813

3. 4

30-34..........- ...........

Under 20--------------

1,660

4.6

40 and over......... .

18-19_________

362
1,298

19
57

5.2
4.4

6 ^822

191
204

2. 7
3.0

25-29............... ........

Births

40-44________ _
45 and over___

Per cent

4,389
2,815
1,015

158
127
57

3.6
4.5
5.6

963
52

5.1
15.4

Order of bitth.

In Table 157 the variations in the stillbirth rates are shown by
order of birth. The rate was much higher for first than for second
infants (4 as compared with 2.5 per cent); it rose steadily with the
increase in order up to seventh, fell off slightly for eighth and ninth,
but rose to the highest point of all (5.5 per cent) for tenth and later
births. This trend of the stillbirth rates was similar to that of the
mortality rates from causes peculiar to early infancy, discussed on
pages 16-18.
T

able

1 5 7 .—

Stillbirth rates, by order o f birth; births in eight cities
Stillbirths

Stillbirths
Order of birth

Order of birth

Births
Number

Per cent

Number Per cent

l ocai-----------

23,780

813

3.4

Fifth.......................

261
126
95
74

4.0
2.5

Fourth....................

6,491
5 ' 080
3,423
2,555

Seventh................
Eighth....................
Ninth..................
■Tenth and later___

2 .8

2.9

Births

1,830
1,310
'968
707
489
927

63
47
47
30
19
51

3.4
3.6
4.9
4.2
3.9
5.5

Interval since preceding birth.

_ The variations in the stillbirth rates (Baltimore only) by interval
since the preceding birth, as measured by the difference in even years
between the mother’s ages at successive confinements, are shown in
Table 158. The rate was markedly higher for the short-interval
babies— those born to mothers who were only one year older at the

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time of the birth of the scheduled infant than at the time of the next
preceding birth— than for the babies of mothers who were two or
three years older, the rates being 3.6, 3.1, and 2.4 per cent, respec
tively. But the rate was even higher (3.9 per cent) for births to
mothers who were four years or more older than at the time of the
next preceding confinement. For none of these groups, however, was
the rate so high as for first infants.
T a b l e 158 .— Stillbirth rates, by interval since preceding birth;1 births in Baltimore
Stillbirths
Interval since preceding birth 1

Births
Number Per cent

Total.__________

11,195

398

3.6

First birth .................. .
Second and later births..

2,999
8,196

131
267

4.4
3.3

One year__________
Two years_________
Three years..............
Four years and over.
Not reported______

2,149
3,045
1,398
1,556
48

77
95
34
60
1

3.6
3.1
2.4
3.9
2.1

For definition of interval see p. 60.

T Y P E OF B IR TH

Prematurity.

Of the 813 stillbirths included in the study about three-fifths
(59.3 per cent) were full term and two-fifths (40.7 per cent) .premature.
Of the premature the proportion born dead was 11 times as high as
of the infants born at term, the percentages being 24.6 for premature
births and 2.2 per cent for full-term births. (See General Table 4,
p. 188.) If data were available for classification by the exact period
of gestation, the rates would doubtless show a rapid decline in the
percentages of stillbirths as the periods of gestation increased.
Plural births.

The proportion of stillbirths was much higher for the plural than
for the single births— 5 per cent as compared with 3.4 per cent. In
the group of full-term single infants the proportion of stillbirths was
only 2.1 per cent, but in that of full-term twins and triplets it reached
3.8 per cent. The relative rates were reversed, however, for the pre
maturely born, the higher rate (25.8 per cent) being found for the
single and the lower (11.1 per cent) for the plural. (See General
Table 46, p. 204.)
Type o f delivery.

The proportion of stillbirths among the cases of instrumental deliv
ery (which included about 1 in every 15 births) was very high— 12.2
per cent, or over four times the percentage of stillbirths among normal
deliveries, 2.8. In fact, 104 stillbirths were delivered with the aid of
instruments as compared with only 23.8 which would have been
expected if the rate for normal deliveries had prevailed.5
One of the 16 cases in which the mother was delivered by Caesarean
section resulted in a stillbirth.5
8

The data on these points were for Baltimore only.

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ABPEtfhlX A — Stillbirths

SEX

A larger proportion of the stillborn than of the live-born infants
were of the male sex— 54.1 as compared with 50.8 per cent. The
stillbirth rate for the male was higher than that for the female infants;
3.6 per cent of the former as compared with 3.2 per cent of the latter
were born dead. The causes of the slightly greater tendency toward
stillbirth among the males are doubtless associated with the some
what greater average size of the male infant, which results in more
difficult labor. This hypothesis is supported b y the fact that in the
group of male infants born at term the percentage of stillbirths was
2.4, or one-fifth higher than that (1.9) in the group of female in
fants born at term, whereas for the males who were bom prematurely
the proportion of stillbirths was not so large as that for the females.
(See General Table 4, p. 188.)
C O LO R A N D N A T IO N A L IT Y OF M O T H E R

In Table 159 stillbirth rates are given for each color and nationality
group. The most striking fact shown was the extremely high rate
(8 per cent) for births to colored mothers, which was twice as high
as the highest rate for births to mothers of any other color or nation
ality group. For a plausible explanation of this unusually high rate
reference may be made to the great prevalence of syphilis which Dr.
Whitridge Williams found among negro women confined in hospitals
in Baltimore, the city in which the great majority of the negro mothers
included in the study lived.6 Another possible cause is the greater
prevalence of rachitic pelves among negro mothers.
As for the other color and nationality groups, the exceptionally
low stillbirth rates for infants born to Jewish and to Portuguese
mothers were noteworthy. These low rates corresponded to low
mortality from causes peculiar to early infancy, and in the case of the
Jewish group to low mortality in the first month; among the babies
of Portuguese mothers the mortality in the first month was increased
by many deaths charged to gastric and intestinal diseases (p. 105).
The French-Canadian group had an unusually high proportion of
stillbirths (4 per cent), and the percentage for the Italian group was
also high (3.6). The rate for the native white group was third from
the lowest, being higher only than the rates for births to Jewish and to
Portuguese mothers.
6 ‘ It has long been known that this disease (syphilis) plays an important part in the causation of fetal
deaths.” Williams, J. Whitridge, M . D .: The Limitations and Possibilities of Prenatal Care; based
upon the study of 705 fetal deaths occurring in 10,000 consecutive admissions to the obstetrical department
of the Johns Hopkins Hospital, p. 35. American Association for Study and Prevention of Infant Mor
tality, Boston, 1914.

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1 5 9 .—

IN F A N T

M O R T A L IT Y

Stillbirth rates, by color and nationality o f mother; births in eight cities
Stillbirths
Color and nationality of mother

Births
Number Per cent 1

Total.............................- .............- ................................................. -

3.4

23,780

813

22,196

686

3.1

12,475
9,721
1,480
1,267
1,119
803
1,306
687
3,056
3

373
313
54
34
45
27
40
18
94

3.0
3.2
3.6
2.7
4.0
3.4
3.1

1,584

127

2 .6

3.1

1
8 .0

Not shown where base is less than 1 0 0 .

E M P L O Y M E N T OF M O T H E R S D U R IN G P R E G N A N C Y

The employment of mothers during pregnancy, as Table 160 shows,
appeared to exert a marked influence over the occurrence of still
births. The rate for births to mothers who were employed away
from home during pregnancy was 4.9 per cent, or over one and onehalf times that found for births tq mothers who were not gainfully
employed (3.1 per cent). The.rate for births to mothers employed
at home was 3.5 per cent. These variations were similar to those
found in the mortality rates for these groups from causes peculiar to
early infancy (p. 132).
T

able

1 6 0 .—

Stillbirth rates, by employment o f mother during pregnancy; births in
eight cities
Stillbirths

Employment of mother during pregnancy

Births
Number Per cent 1

Employed away from home................ .........................................................-

23,780

813

3.4

3,244
3,926
16,603
7

160
138
514

4.9
3.5
3.1

Not shown where base is less than 100.

E A R N IN G S O F FATH ER

Table 161 indicates that the stillbirth rates varied with the amounts
of father’s earnings, falling as the earnings increased and rising as
they decreased. The highest stillbirth rate (6.8 per cent) was found
in the “ no earnings” group and the lowest (2.2 per cent) in the group
“ $1,050-$1,249,” though the group “ SI,250 and over” had nearly
as low a rate (2.7 per cent). The groups “ under $450” and “ $450$549” had rates markedly above average—4 and 4.1 per cent, re
spectively.

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A P P E N D IX

T able

161.—

173

A . ------S T I L L B I R T H S

Stillbirth rates, b y ea rn in g s o f fa th e r ; births i n seven cities

Stillbirths
Earnings of father

Number

$450-$549 .
$550-$649.................
$650-849.................

Stillbirths
Earnings of father

Births

745

3.3

3,214
2,947
3,014
5; 207

129

4.0
4.1
3.5
3.0

106
157

Number Per cent

Per cent

22,281

120

Births

$850-$l,049...... ........
$1,050-$l,249______
$1,250 and over.......
No earnings______
Not reported.......

3,445
1,423
2,315
336
380

100
32
63
23
15

2.9

2.2
6.8

2.7

3.9

SUMMARY

The causal factors which appeared to have exerted the greatest
influence over the stillbirth rates were those connected with the
mother’s health and those connected with the type of birth. The
contrast between the stillbirth rate for the babies of mothers who
died during the month following confinement and that for the babies
of mothers who survived the year was especially marked, the rates
being 32.5 per cent and 3.3 per cent, respectively. Likewise marked
was the contrast between the proportions of infants born dead among
the premature and among those born at term— 24.6 per cent and 2.2
per cent, respectively.
Other factors that exerted an influence over the frequency of stillbirths
included age of mother, which showed itself in high rates for the
infants of the youngest and the oldest mothers; order of birth, which
showed itself in high rates for first babies and for births of late orders;
and interval since preceding birth, which showed itself in a high per
centage of stillbirths for the group of babies born after short intervals.
The stillbirth rate was higher for male than for female infants. Among
the colored the frequency of stillbirths was -much higher than in any
other race or nationality group; the lowest frequencies were found
for the babies of Jewish and Portuguese mothers. The proportion of
infants born dead was much higher among those born to mothers who
were employed away from home during pregnancy than among those
born to other mothers. Relatively high stillbirth rates were found in
families in which the father’s earnings were low.

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AP PE N D IX B .— M E T H O D OF STU D Y 1

The object of the studies on which this report is based, was to show
the causes of infant mortality and its relation to various social,
economic, and physical conditions. For this purpose it was essential
to secure accurate mortality rates, not only for the group as a whole,
but also for each of the subgroups the proportions of deaths in which
were to be compared. It was not essential, however, that all the
births in each city studied should be included, provided that accurate
mortality rates could be obtained for those selected and that those
selected constituted fairly representative samples.
INFANT MORTALITY RATE

In order to secure an accurate mortality rate for the births selected
the procedure was adopted of following each infant from the date
of birth until he reached his first birthday, or until his death if he died
under the age of 1 year. The ratios of deaths to births as thus computed
are true “ probabilities of dying ” and are independent of variations
in the birth rate, a factor which may introduce inaccuracies into
infant mortality rates as commonly calculated by dividing the
births that occur during a given year into the infant deaths during
the same period.
EXCLUSIONS

In order not to introduce unnecessary and unknown errors of
sampling into the data all the live births that occurred within given
years in the cities selected for study, with certain definite exceptions,
were included. The exceptions fell into five well-defined groups:
(1) Illegitimate births, (2) births to nonresident mothers, (3) births
to mothers who were known to have moved away from the city, (4)
births to mothers who had moved away from the addresses given
on the birth or death certificates and could not be traced, andv (5)
births for which the information was incomplete or appeared un
reliable. The reasons for these exclusions were intimately connected
not only with the problems involved in locating and interviewing
the mothers but also with those involved in the accurate computation
of an infant mortality rate.
Illegitimate births were excluded partly because it was more
difficult to secure for them accurate and reliable data and partly
because the items of information that could be obtained would have
required a special analysis separate from that for the legitimate
births. An attempt to secure such information was made in Balti
more, and the results were presented in a special section of the report
dealing with that city.2
1See also the appendixes to the separate studies of infant mortality made by the Children’s Bureau
and “ Infant-mortality studies of the Children’s Bureau,” by Robert M . Woodbury, in Quarterly Publica
tions of the American Statistical Association for June, 1918, Vol. X V I, pp. 30-53.
2Infant Mortality—Results of a Field Study in Baltimore, M d., based on births in one year, by Anna
Rochester, pp. 155-176. U. S. Children’s Bureau Publication No. 119, Washington, 1923,
174

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175

Births to nonresident mothers were excluded partly because of the
difficulty and expense of locating and visiting such mothers after
they had returned to their homes but also partly because the condi
tions surrounding these infants might not he typical of those in the
city which was being studied. Especially would this latter be true
of the maternity cases sent from outlying districts to the city hos
pitals on account of some expected complication of confinement.
Births to mothers who were known to have moved away from the
city, like those to nonresident mothers, were excluded in part be
cause of the difficulty and expense of locating and visiting the mothers
to secure the necessary information and in part because the circum
stances surrounding the infants after removal from the city would
not have been typical of the city. A still more serious objection to
including these births, however, was that in many cases it would
have been impossible to secure records even of deaths which had
occurred among the infants in this group after the families had
moved. Accurate statements of the ages at which the infants left
the city, furthermore, could not have been obtained without finding
and interviewing every mother.
Births to mothers who had removed from their addresses in the
city as given on the birth certificates and who could not be traced
were necessarily excluded. In the great majority of cases, doubt
less, they had moved away from the city without leaving with their
former neighbors any information as to their new addresses.
These groups of migratory families would furnish an interesting
study, if data were available, since the mortality rate for their in
fants might be affected by shifting from one place to another. But
the difficulties in the way of obtaining the necessary information for
the present series of reports were such that no special study could be
made. The data that were secured in regard to such excluded cases
yield only a minimum statement of the mortality that prevailed
among the infants in these families.
Finally, a small number of infants were omitted because the data
secured for them were fragmentary or obviously unreliable.
With these five groups of infants excluded, the problem remained
of securing a complete account of all the other infants born in the
selected year or of selecting for study a group for which accurate
mortality rates could be secured. With two exceptions, Akron and
Baltimore, all the cities studied were in the United States provisional
birth-registration area and could therefore be presumed to have
fairly complete birth registration. In the progress of the work,
however, a number of death certificates were discovered for infants
for whom no birth certificates were on file, and in some of these
cases it was definitely ascertained that the infants had been born in
the city and in the year selected for study. To include these infants
who died without making an effort to locate unregistered infants
who survived the year, however, would have resulted in a bias in
the mortality rates. Accordingly, in three cities, Manchester, New
Bedford, and Brockton, the studies were limited to infants whose
births were registered. It should be noted, however, that in New
edford and Brockton special house-to-house canvasses had been
made by the State as part of the routine of checking birth registra
tion; in these cities, therefore, birth registration was •exceptionally
complete.

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In other cities more or less comprehensive efforts were made
to supplement birth-registration lists, and all births in the year and
in the area selected for study were included except those belonging to
the excluded groups. In Johnstown, registration was found to have
been defective in the Serbian neighborhoods, and many births were
added b y consulting the registers of baptisms in the Serbian churches
and by inquiring at each home visited in the Serbian quarter of
the city as to whether other children had been born in the neighbor
hood during the year selected for study.3 These births, added to
those which had been registered, formed the basis of the study.
In Saginaw many births were added to the list as a result of extended
neighborhood inquiries, consultations of baptismal registers, and
other measures.4 In Waterbury the list of registered births was
supplemented with others found in the course of a house-to-house
canvass and an examination of church registers of baptisms and of
the records of social agencies and institutions.5 In Akron, a city
not in the birth-registration area, a house-to-house canvass was
made, and the results were compared with the list of registered
births and with the records of baptisms.6 In Baltimore a vigorous
campaign for improved registration was in progress during the year
selected for study. (Maryland was admitted to the birth-registra
tion area in the following year.) Though during the progress of the
inquiries made by the Children’s Bureau in that city many infants
whose births had not been registered were discovered, all such
cases were reported to the health department; and this department,
after obtaining the information asked for on the birth certificates,
registered the births. In Baltimore, therefore, every case located
became, if it was not already, a registered birth.7
The efforts made to locate unregistered births may have failed to
complete the lists of those that fulfilled the requirements for in
clusion in the studies, and to the extent that such births were omitted
an element of selection may have made the results not exactly
typical of the cities studied. A difficulty, however, that arises in
connection with a failure to locate unregistered births is the fact that,
because death' registration is usually more complete than birth
registration, infants whose births were unregistered were more
easily learned of and therefore more likely to have been included in
the study if they died than if they lived, since if they died their
deaths would have been recorded. The omission of any considerable
number of unregistered births, therefore, except in those cities in
which only registered births were included, would have meant a
tendency toward an overstatement of the mortality rate, especially
for those groups, if any, in which omissions were numerous.8 The
point should be emphasized, however, that the results could not have
been influenced b y omissions of unregistered illegitimate births, of
3
Infant Mortality—Results of a Field Study in Johnstown, Pa., based on births in one calendar year, by
Emma Duke, p. 13. U. S. Children’s Bureau Publication No. 9. Washington, 1915.
. * Infant Mortality—Results of a Field Study in Saginaw, Mich., based on births in one year,bj&Nila F.
Allen, pp. 11, 6 8 ff. U. S. Children’s Bureau Publication No. 52. Washington, 1919.
f Infant Mortality—Results of a Field Study in Waterbury, Conn., based on births in one year, by
Estelle B . Hunter, pp. 20 ff. U. S. Children’s Bureau Publication No. 29. Washington, 1918.
eInfant Mortality—Results of a Field Study in Akron, Ohio, based on births in one year, by Theresa
S. Haley, pp. 76 fl. U. S. Children’s Bureau Publication No. 72. Washington, 1920.
i infant Mortality—Results of a Field Study in Baltimore, M d., based on births in one year, by Anna
Rochester, pp. 185 fl. U. S. Children’s Bureau Publication No. 119. Washington, 1923.
8 In Baltimore, where births were registered as soon as they were located or where infants whose births
were unregistered were looked up immediately and registered if records of their deaths.were filed, any omis
sion of unregistered births would likewise have affected the mortality rates.

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OF S T U D Y

177

births to nonresidents, or of births in families that moved away
from the city, since all births of these classes were excluded. Only
the omission of unregistered legitimate infants of resident mothers,
born in the selected year in the area studied, who were still living in the
area at the time the visits of agents were made or who had died at
ages under 1 year before that time, would have affected the con
clusions. But these infants were the easiest to locate by means of
neighborhood inquiries or of a house-to-house canvass. Where such
inquiries were thorough or where such a canvass was made the
chance of important omissions was relatively slight.
In the nature of the case it is extremely difficult to assess the
importance of such omissions. In Akron detailed records of the
results of the canvass permit the testing of its completeness. It
should have produced a report for each infant born in the selected
year and living in Akron at the time the canvass was made. Of those
whose births were registered and who survived the first year of life—
except children who were temporarily absent, who had moved away
from the city, or who had died at ages over 1 year— the canvass should
have found practically all. It failed to find 7.6 per cent of them and
may therefore be regarded as 92.4 per cent perfect. The number of
unregistered births discovered through the canvass and by other
means formed 13.7 per cent of the total, which showed that registra
tion in Akron was not more than 86.3 per cent perfect. The chance,
therefore, that a case would not be located by either of these methods
was very small. The two methods of locating births, used inde
pendently for the same purpose, would have located, according
to the mathematics of probability, approximately 99 per cent of all
cases that fulfilled the requirements for inclusion in the study. For
other cities, unfortunately, material is not available for similar
computations.
IN F A N T M O R T A L IT Y R A TE S IN EXC LU D ED G R O U PS

On account of differences in detail between the methods followed
in the several cities the cities were divided into three groups: First,
those in which only the registered births were considered for inclusion
in the study, comprising Manchester, Brockton, and New Bedford;
second, those in which all births located were considered for inclusion
and in which information was available as to whether or not each
birth had already been registered, comprising Johnstown, Saginaw,
Waterbury, and Akron; and, finally, Baltimore, in which all births
located were considered for inclusion but at the same time were
placed on the register if not previously recorded, so that, in fact, all
the births included were registered.
Group I.

In the cities included in Group I— Manchester, Brockton, and NeW
Bedford— in which the births studied were limited to those which had
been recorded, according to Table 162, a total of 7,053 births were
found to have been registered; of these the information obtained in
regard to 5,361 satisfied all the conditions for inclusion, and that
obtained in regard to 1,692 failed to satisfy one or more of the
conditions.

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IN F A N T

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The mortality rate for the group of 70 births which were excluded
solely on the ground of illegitimacy was 314. This group, it should
be borne in mind, did not include all the illegitimate births but only
those which did not fall into one of the other groups of exclusions.
The nonresident group of registered births, which numbered 134,
had a mortality rate somewhere above 74.6. This figure is based upon
the infants whose births were registered and the deaths among them
before they were taken away from the city, and is obviously an under
statement. The deaths enumerated for this group doubtless included
most if not all of those that occurred during the first two weeks of life
and included a certain proportion of those that occurred later, dependin gon the average age of the infants when they were taken away.
The group of babies whose families had moved away from the
city numbered 719 and had a mortality rate of over 157.2. For
reasons similar to those given for the nonresidents this figure also
must be considered an understatement, since deaths after these
infants had left the city were not included in the computation.
Since, however, the average age when taken away from the city
must have been higher for these infants than for the nonresident
infants, more of the deaths that occurred among the former doubtless
were included— a fact which accounts, in part at least, for their
higher minimum mortality rate.
T a b l e 162 .— Infant mortality rates fo r excluded groups, by reason fo r exclusion and

registration of births; births in Manchester, Brockton, and New Bedford

Inclusion and exclusion,
and reason for exclusion

Total

Un
regis
tered

Total

150

1,089

150

712
377

712
289

272
131

267
127

7,203

7,053

Included__________________
Excluded--------------- -----------

5,361
1,842

5,361
1,692

Nonresidence and lack
of information-----------Not found_________
Data incomplete and

1,630
737

1,622
733

36
137
720
70
142

36
134
719
70

Nonresident..............
Removed._________
Nonregistration of birth.

Births Births
regis unreg
tered istered

Regis
tered

Total____________

Infant mortality rates 1

Infant deaths

Live births

17
3
1

1 ,0 0 1

113

142

Births Births
regis unreg
tered istered

151.2

141.9

586.7

132.8
204.7

132.8
170.8

586.7

5
4-

166.9
177.7

164.6
173.3

73.0
158.3

74.6
157.2

584.5

114

Total

584.5

1Not shown where base is less than 100.
2 Including

only births in the resident and located groups.

The group of infants whose births were registered but who were
not found had an even higher known rate (173.3); and since the pre
sumption is that in most of these cases also the families had moved
away from the city, some deaths probably occurred among these
infants in addition to those represented in this figure. Since, how
ever, in the cities in Group I no house-to-house canvasses nor system
atic neighborhood inquiries were undertaken, this group may have
included many infants in families difficult to locate merely because
they had moved from one address to another in the same city. If
so, the rate is only slightly understated.

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179

Of the 36 infants whose births were registered hut for whom such
data as were obtained were incomplete or seemed unreliable nearly
half had died under 1 year of age. This extremely high proportion of
deaths was undoubtedly due to the fact that difficulty in securing
accurate and complete information was encountered more often in
cases in which the infants had died than in those in which they
were still living, and more often in cases in which the mothers or
both parents had died or deserted—groups in which the mortality
rates would be expected to be high— than in those in which the
family conditions were normal.
Since in the cities of Group I no effort was made to discover unreg
istered births other than those discovered through the death certifi
cates or through some more or less accidental source of information,
the number of unregistered births shown is considerably smaller than
the true number. The rate of 584.5 for the group of births excluded
because not registered is, therefore, no indication of the true mor
tality in this group.
The numbers of unregistered births excluded because “ not found,”
“ removed,” or “ nonresident” were too small to afford a satisfactory
basis for calculating rates; furthermore, for these groups also the
figures are meaningless, since no effort was made to ascertain the
true number of births.
Group II.

In the cities included in Group II—Johnstown, Saginaw, Waterbury, and Akron— in which special efforts were made to supplement
the lists of registered births, according to Table 163, a total of
8,493 births were known to have occurred, of which 6,809 satisfied
all the conditions for inclusion and 1,684 were excluded because the
information obtained failed to meet one or more of these conditions.
The 82 infants excluded solely on the ground of illegitimacy had a
mortality rate of 256. As in the cities of Group I, however, only
those illegitimate births which did not fall in one of the other exclu
sion groups were here included. The number, therefore, fails to
show the true extent of illegitimacy in these cities. Nevertheless
this mortality rate is probably approximately accurate for the res
ident and located illegitimate infants.
In these cities the births to nonresident mothers numbered only 98.
The mortality among such infants whose births were registered was
more than 69; for reasons stated in discussing births of this class in the
cities of Group I the known deaths give a rate which is obviously an
understatement. Of the 11 infants born to nonresident mothers,
whose births were not registered, 5 died under 1 year of age.
This mortality proportion, however, is not significant, since the num
ber of births appearing in the group is far below the true number,
which the methods of canvassing and of neighborhood inquiry were
not adapted to ascertain.

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IN F A N T

M O R T A L IT Y

Infant mortality rates in excluded groups, by reason fo r exclusion and
by registration of births; births in Akron, Waterbury, Saginaw, and Johnstown 1

T able

Live'births
Inclusion and exclusion, and
reason for exclusion
Total

Infant deaths

Regis Unreg
tered istered

Total

Infant mortality rates2

Births Births
regis unreg
tered istered

Total

Births Births
regis unreg
tered istered

Total____________

8,493

7,609

984

928

720

208

109.3

95.9

211.4

Included__________________

6,809
1,684

6 ,0 1 1

1,498

798
186

726

678
142

148

106. 6

1 2 0 .0

96.2
94.8

185.5
322.6

1,602
390

1,426
'296

176
95

181
48

122

113.0
123.1

85.6

335.2

8 8 .1

9
87
1,036
72

2
11
68
10

105.2

82.1

Nonresidence and lack
Not found_________
. Data incomplete and
unreliable........... .
Nonresident............
Illegitimacy__________

98
1,103
82

1 In these cities nonregistration of birth was
2 Not shown where base is less than 100.

202

6
11

116

5
31

not a reason for exclusion.

The registered births to mothers who moved away from the city
numbered 1,035, and for this group an infant mortality rate of
82.1 was found. This figure also, for reasons previously explained,
was an understatement on account of the omission of deaths after
infants had been taken away from the city. The unregistered
births to mothers who moved away were obviously not completely
reported, and therefore the proportion of deaths in this group is not
significant.
The registered births to mothers who were not located numbered
295, and the known mortality among these infants was 88.1, prob
ably an understatement. The corresponding figures for the un
registered births to such mothers are not significant.
A small number of cases (11) were excluded because the data
obtained were incomplete or seemed unreliable. Six of these in
fants died under 1 year of age.
Group f f l.

In the one city in Group III, Baltimore, as in Group II, non
registration of births was not a reason for exclusion. Mortality
rates could not be figured separately, however, for the births in
Baltimore that were not registered prior to the time of the study
but were figured for all registered births including those newly
found. The rates for all the births should therefore be compared
with those for the corresponding totals in Group II. Another
important difference between these figures and those for Group II
is that in Baltimore all the births that were ascertained to have been
illegitimate were classified as excluded on the ground of illegitimacy,
whereas in other cities they were classified as excluded on that
ground only in case they would otherwise have been included.
This difference, however, is to some extent offset by the fact that in
Baltimore efforts were made to ascertain whether an illegitimate
infant died after being taken away from the city, and if he was
found to have died his death was counted in computing mortality
rates for the illegitimate infants; whereas in other cities no effort
was made to follow infants after they had left the city and only
deaths within the city were counted in computing rates.

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181

A P P E N D IX B .— M E T H O D ' ÓE S T U D Y
T

able

1 6 4 .—

Infant mortality rates fo r excluded groups; Baltimore 1

Inclusion or exclusion, and reason for exclusion

Total___ ____ _______
Included_______________
Excluded...______
Nonresidence and lack of information
Not found________ _
Data incomplete and unreliable_____
Nonresident____________
Removed_________
niegitimacy____ __________

Live
births

Infant
deaths

Infant
mortality
rates

13,477

1,551

115.1

10,797
2 , 680

1,117
434

103. 5
161.9

1, 725
284
23
338
1,080
955

153
40

88.7
140.8
478.3
85. 8
67.6
294.2

29
73
281

1 Although in the present discussion the illegitimate groups are classed as excluded, detailed data were
secured for a considerable proportion of them and formed the basis for a special section in the report on
infant mortality in Baltimore. See Infant Mortality—Results of a Field Study in Baltimore, M d based
on births in one year, by Anna Rochester, pp. 155-176 (U. S. Children’s Bureau Publication No. 119.
Washington, 1923).

The mortality rate for the illegitimate infants, based upon all
births and the known deaths of such infants, was 294.2. This rate
constitutes an understatement, for the deaths included only those
which were registered in Baltimore or which, though they occurred
after the babies had left the city, were discovered during the course
of the study. A considerable number of the infants in this group—
256, or 27 per cent— could not be traced. The deaths omitted from
the record, assuming fairly complete death registration in Baltimore,
must have been those which occurred after the infants had left the
city and which were not traced, and the proportion of omitted
deaths must have corresponded roughly, therefore, to that propor
tion of the time lived by all the illegitimate infants during their first
year of life that was lived by such infants after they had been taken
away from Baltimore. But without evidence as to their average
age at the time of removal or even positive evidence that they left
the city when under 1 year of age, it is impossible to estimate the
true mortality rate for the illegitimate babies who could not be
traced.
The nonresident and the removed groups appear to have had mor
tality rates markedly below the average for the city— 85.8 and 67.6,
respectively. These low rates, however, obviously understate the
true mortality among these groups, since they were based only on
deaths that took place in the city and additional deaths may have
occurred after the infants were taken out of the nity. The rate of
140.8 for the “ not-found” group is affected b y another type of error:
Infants who died in the city were almost certain to be registered,
whereas those who lived and had not been registered at the time of
birth were often, probably, not discovered in the course of the efforts
made to locate unregistered births (in many cases the families had
left the city before inquiries were commenced) and hence were never
in the group at all. In other words the group includes too many
deaths in proportion to its births.
" The group of cases omitted because of incompleteness or unrelia
bility of data, also, was doubtless biassed by the tendency to include
96515°— 251------ 13

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182

CA U SAL FAC TOES IK

IN F A N T

M O E T A L IT Y

a disproportionate number of infants who died. The number of
cases, too, was small. The rate for this group, therefore, is probably
not significant.
For the entire group of infants excluded because of nonresidence
or lack of information the mortality rate (88.7) is affected b y two
opposite and to a certain extent counteracting tendencies— the
tendency to omit deaths because of the removal of the infants from
the city when they were less than 1 year old and the tendency to
omit births that would have been more easily discovered if all infants
born in the city in the given year had lived there until the study was
completed.
SU M M ARY

Exclusion of certain groups was found necessary not only because
detailed information was lacking in certain cases but also in order
to eliminate groups in which it was difficult or impossible to calculate
yalid mortality rates. The analysis shows that the rates found for
the excluded groups were understatements, approximately correct
or entirely without significance, depending upon the reason for exclu
sion and the method of study adopted. No general or combined
result for the excluded groups is of significance, therefore, since the
particular characteristics o f the separate groups which affect the
interpretation of the rates are lost sight of in the process of com
bining the results.
The same policy of exclusion was adopted for stillbirths as for live
births, in order that the rates obtained by dividing the number of
infants bom dead b y tbe sum of those born alive and those bom
dead might be on a sound basis. In addition, all miscarriages (births
of less than seven months’ gestation) were excluded.9
A special reason for the exclusion of stillbirths to nonresident
mothers was the possibility of overweighting with complicated cases
in which, because of their unusual difficulties, the special facilities of
the maternity hospitals of the cities had been sought. Likewise
excluded were stillbirths to mothers who had moved away prior to
the visit of the agent and to mothers who could not be located.
In these cases it would have been difficult to obtain the information,
and, furthermore, since the corresponding live births were omitted,
the exclusion of the stillbirths was necessary in order to compute a
fair rate. In many of these cases, moreover, it was impossible to
determine whether the case was a stillbirth or a miscarriage, since
the period of gestation could not be learned.
No stillbirth rates can be calculated for the various excluded
groups because of the uncertainty (just mentioned) as to the period
of gestation of the excluded cases. The numbers of stillbirths
excluded for the various reasons are given in Table 165.
9 In Baltimore miscarriages of more than 4 months’ gestation were required to he registered; in the report
for Baltimore, accordingly, these were included in the discussion. For the present report, however, in
which the results for all the cities are combined, dead births of less than 7 months’ gestation were uniformly
excluded.

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A P P E N D I X B .-----M E T H O D OE S T U D Y

183

T a b l e 165 .— Stillbirths and miscarriages included in and excluded from detailed

analysis, by reason fo r exclusion; eight cities

Inclusion or exclusion and reason for exclusion

Stillbirths
and mis
carriages

Total known stillbirths and miscarriages.

1,874

Stillbirths included...................................... ....................
Miscarriages and stillbirths excluded________________

813
1,061

Miscarriages_____________________ J .___
Stillbirths 1___ ..._______________________
Nonresidence and lack of information.
Not found_______________ ______
Data incomplete or unreliable___
Nonresident_____________ ______
Removed______________________
Illegitimacy_____ _______________ _
Foundlings *____ __________________
Nonregistration of birth......................

645
416
260
94
7
49
110
117
22

1 May include some miscarriages. In many cases of the “ not found,” “ nonresident,” “ removed,” and
foundling” groups the period of gestation could not be learned.
1 No report as to legitimacy.

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AP PE N D IX C.— M E T H O D OF AN ALYSIS

In dealing with a subject in which so many causes are at work as
in infant mortality, some method of separating the influence of a
single cause from that of others is essential. In the present report,
recourse has been had to the method of expected deaths developed
and applied to the study of infant mortality "by Prof. Harald Westergaard, of the University of Copenhagen.1 . .
. .
The principle involved in this method is simple. Suppose it is
desired to show the influence of type of feeding upon infant mor
tality, regardless of differences in months of age. First, the mor
tality rates for breast-fed infants in each month of life are ascer
tained, and second, the numbers of infants artificially fed in the
corresponding months are multiplied by these rates in order to de
termine the number of deaths that would have occurred among the
artificially fed provided the rates found for the breast fed had pre
vailed. The ratio between the number of expected deaths as thus
computed and the number of actual deaths is a measure of the rela
tive mortality among the artificially-fed as compared with that among
the breast-fed infants uninfluenced by the differences in the ages at
which the two types of feeding were given.
An alternative procedure which leads to the same general result is
to use the average death rates in each month instead of the rates for
breast-fed infants only. In this procedure the actual deaths among
the artificially fed are compared with the number expected if the
average mortality had prevailed among them, and the result gives
the mortality among the artificially fed as compared with the aver
age mortality after differences in the ages at which artificial feeding
was given have been taken into account. The actual deaths among
the breast fed can be similarly compared with the number expected
if average rates had prevailed; and this comparison shows the ad
vantage which the breast-fed infants had after taking into account
the ages at which breast feeding was given. A comparison of the
mortality among the artificially fed with that among the breast fed
can then be made, since the ratio for each group is a comparison
with the average.
To take a second illustration, suppose it is sought to determine
whether the mortality among infants of mothers who were employed
during pregnancy exceeds that among infants of mothers who were
not employed. Suppose further that the obvious classification of in
fants into two groups, those whose mothers were and those whose
mothers were not employed, yields mortality rates that show a greater
mortality among the former. This result may be due to the fact
i For an example of this method, see Die Lehre von der Mortalität und Morbilität, by H. Westergaard,
336-338 (Second Edition, 1902). See also “ Westergaard’s method of expected deaths as applied to
the study of infant mortality,” by Robert M . Woodbury, in Quarterly Publications of the American
Statistical Association, Vol. X V III, pp. 366-376.

■d o .

184

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C .— M E T H O D OF A N A L Y S IS

185

that the group of infants whose mothers were employed had more
^|ianJ1^s due proportion of babies of certain nationalities for which
the death rates were unusually high. The next step is, therefore,
divide the infants in each nationality into two groups, those whose
mothers were and those whose mothers were not employed, and to
compare the mortality in each of these groups for each nationality,
lh e question may then arise as to whether the relative mortality in
the two employment groups was not affected by a disproportionate
weighting of one with mfants whose fathers’ earnings were low. If
such a disproportionate weighting is found, the process of subdi
vision is carried further; the births are classified according to both
nationality of mother and father’s earnings, in each of these groups
the mortality among babies of employed mothers is compared with
that among babies of mothers who were not employed, and finally a
conclusion is reached as to the effect, if any, of the mother’s employment upon infant mortality.
In this process of subdivision, the number of groups to be com
pared is continually increased until it becomes difficult for the mind
to grasp the conclusions. Evidently some method of summarizing
the comparisons of the several groups is necessary; but if the births
and deaths in each group are merely added together, the process
gives only the figures from which the analysis originally proceeded.
Ihe method of summation should produce conclusions independent
ot the differences in distribution that complicated the original find
ing?- ^he °bvious method is to combine the evidence which the
different groups present on the question of the relative mortality of
the babies of employed mothers, which is done by the simple expedient
of calculating the expected deaths in each group— the deaths expected
at the rate found for the babies of nonemployed mothers or, if pre
ferred, the deaths expected at the average rate for all babies in the
group. B y adding together on the one hand all the actual and on
tiiG otiiGr 8Jl tliG GxpGctGcL dG&ths tliG validity of th-G comparisons
between the several groups is kept and the evidence is summarized.
Ih e final result is then in the form of a comparison of two numbers
the actual and the expected deaths, a comparison in which the in
fluences of the factors according to which the material was subdivided
have been eliminated, and which therefore shows the true influence
upon mortality of the factor studied, independent of that of the
eliminated factors.

A further advantage in summarizing the evidence lies in the fact that
the range of variation due to chance, which in each group becomes
relatively large when the material is subdivided and the number of
cases is reduced, becomes relatively small when the results from all
the groups are added together; the conclusion, indeed, secures the
full value of the weight attached to the total number of cases in the
comparison.

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A P PE N D IX D .— G ENERAL TABLES
G e n e r a l T a b l e 1.— Cause of death, by month o f life in which death occurred’,

infant deaths in eight cities

Diarrhea and enteritis________

24
719

9
60

5
23

4
37

Respiratory diseases........................

450

Acute bronchitis.......................
Broncho-pneumonia.................
Pneumonia__________________

70
267
113

14
30

3
15
13

Early infancy___________________

99
830

76 70
697 621

Congenital debility__________

399
343

389 359
221 176
87 86

Epidemic and other communicable
diseases___________________

Whooping cough .....................

Diseases ill defined and unknown..
Other causes__________ __________
Meningitis__________________
Other_______________________

186

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3
35

5
18

8
21

6
21

5
25

3
16

5
18

4
14

1
12

10
21

8
21

3
50

30
45

7
42

2
1

3
3

4
3

3
1

1
1

1
1
1

3
2
2

14
58
199

5
26
65

3
23
46

33
45
9

1
22
8

2
1
1

1
1

1
2

3
1

1
1

1
2

3
4

2
1

23
3
23

112

Other forms of tuberculosis___

12
1
12

51
9
5

4
71

4
77

12
1

162

119 109

15
9

1 Twelfth

| Eleventh

743

| Tenth

Gastric and intestinal diseases____

122

1 Ninth

Seventh

All causes.................... - ........ 2,555 1,028 834 194 204 175 173 165 156 132

1 Eighth

Fifth

| Sixth

Fourth

Second

Third

I 2 weeks, under
1 month

fei
»
weeks
2

Under

Total

Cause of death

Total infant deaths

Infant deaths occurring in specified month of life

1
1
1
1

1
6

3
19

1
8

1
2

8
22

1
1
1

1
2

3
..1
1

3
13

3
24

1
2

2
2
1
8

6
2

1
1

2
2
10

4
3

2
2

2
12

2
6

187

A P P E N D IX D .-----G E N E R A L T A B L E S
General T

able

-Causes o f death, by calendar month o f birth; infant deaths in
eight cities
Infant deaths from specified causes
Epi
demic
Di
All
and
seases
causes Gastric Respir Mal
Ex
and in atory
Early
other
ill
Other
form
testinal
infancy com ternal defined causes
diseases diseases ations
muni causes and un
cable
known
diseases

Calendar month of birth

Total.

2,555

743

450

830

162

January___
February...
March____
April_____
M ay. .........
June______
July............
August.......
September..
October___
November..
December..

214
204
228
228
213
246
226
192
195
198
209

74
75
59
78
61
77
56
42
43
47
62
69

37
38
26
36
40
40
50
37
43
35
33
35

63
60
89
80
69
75
75
67
65
58
69
60

10
10

eneral

202

able

5
13
9
10

9
10

4
3
9
8

199

4
1
1

16
9
16

2
6
1

7
5

21
11

1
1
2

17
16
14

6
8

3
5

12
10

Month o f life in which death occurred, by calendar month o f
birth; infant deaths in eight cities

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

24
13
19
15

72
89
75
70 11
74
9
65 31
67 16
66

60
64
64

13
19
12

24
9
13
7

10
10
6
11

30
25
27
9
9

39
22
22

14
17
17
14

11
11

34
21

16
14
13
10
12

15
13

7
15
24
26
16
15
7
11
12

14
12
6

19
24
20

16
12
8
8
10

9
15
6

24
19
15
8

15
14
9
3
9

10
6
6

12
10
8

7
9
5
19

6
11

7
18

Tenth

Eleventh

Twelfth

119 109

92.

Ninth

Sixth

Fourth
5
9

Fifth

Third

122

214
92
204
85
228
108
228
90
213
81
246
83
226
96
192
83
195 . 78
198
73
209
83
202
76

Second

2,555 1,028 834 194 204 175 173 165 156 132

Seventh

weeks, undér
1 month

HH
5
I Under 2 weeks

Eighth

Total...........................
January.....................
February________ _
March__________
April_________
M ay________ _____
June________ .
July_________ _____
August.................
September............
O ctober....................
November...............
Decem ber...........

Total

Calendar month of birth

Total infant deaths

Infant deaths occurring in specified month of life

7
3
3
8
11

9
14

3
5
7
7
5
12
8
2

11
10
10

14
19

24
7

6
2

7
6
10
10

5
4
9

7
3

9
fv
12
8

7
q
13
s
4
2

188

CAUSAL FACTORS IN

General T

4 .—

able

IN F A N T M O R T A L IT Y

Infant mortality rates, by sex and term; live births in eight
cities
Infant deaths
Total
births

Period of gestation and sex

Live
births

23,780
Full term____________ _______ ____ _____

Male____________ ________________

Full term_________________________ ____
7 months and over_____________ ____

Infant
Number mortality Number Per cent 1
rates 1

22,967

2,555

1 1 1 .2

813

3.4

8 8 .1

482
330

2 .2
2 2 .2

329

24.6

22,241
1,488
•145
1,336
7
51

21,759
1,158
' 145
1,007

1,917
'626
137
483

6
12

12,115

11,675

1,436

123.0

440

3.6

11,303
'793
71
718
4
19

11,027
'629
71
555
3
19-

1,072
359
67
289
3
5

97.2
570.7

276
164

2.4
20.7

520.7

163
I

22.7

11,663

11,292

1,119

99.1

371

3.2

10,938
'693
74
i- 616
3
32

10,732
529
74
452
3
31

845
267
70
194
3
7

78.7
504.7

206
164

1.9
23.7

429.2

164

26.6

540.6
944. 8
479.6

1
1

1
2
2

2
2
1 Not

Stillbirths

shown where base is less than 100.

eneral

5 .—

able

Prevalence o f artificial feeding, by sex and month o f life;
infants in eight cities

Infants surviving at begin Infants surviving at begin Infants surviving at begin
ning of ninth month
ning of sixth month
ning of third month

Sex
Total

Artificially fed
during third
month

Total

Total_______

General

Total

21,735

4,431

20.4

2 1 ,2 2 2

6,145

29.0

20,812

7,268

34.9

10,955
10,780

2,288
2,143

20.9
19.9

10,685
10,537

3,154
2,991

29.5
28.4

10,445
10,367

3,702
3,566

35.4
34.4

6 . — Proportion o f births to mothers o f nationalities with high
infant mortality rates, by sex; live births in eight cities

able

Sex

Total.
M ale...
Female.
1

Artificially fed
during ninth
month
Number Per cent

Number Per cent

M a le .......................
Female___________

Artificially fed
during sixth
month

Including French-Canadian, Polish, Portuguese, “ other foreign bom ,” and colored.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

189

A P P E N D IX D .— G E N E R A L T A B L E S
G

T a b l e 7 . — Infant mortality, by cause o f death, term, and interval be
tween confinement and death o f mother; births in eight cities to mothers who died
at or within one year after confinement

eneral

Births to mothers who died at or within one year after
confinement
Infant deaths from specified
causes

Term and interval between confinement and
death of mother
Live
births

Total............ ........... ........... _.........

Gastric
All
and in- Early Other
causes testinal infancy causes
diseases

Stillbirths

172

140

Full term.....................................
Premature___________________
Period of gestation not reported.

132
38

111

35
27

13
3

21
10
1

Mother died within 1 month.....................

Full term...............................................
Premature_________________________
Period of gestation not reported_____

52
29

22
1

19
7

12
21
1

Mother died after 1 month______________

Full term...............................................
Premature_________________________

75
9

5
5

10
1

Interval not reported: Full term..............

eneral

24
1

19
1

8 . — Type of feeding, by month o f life; infants in eight cities
whose mothers died at or Within one year after confinement

able

Infants whose mothers died at or within one year
after confinement
Month of life
Total

First____
Second..
Third___
Fourth. .
Fifth___
Sixth___
Seventh..
Eighth...
Ninth___
Tenth___
Eleventh.
Twelfth..
1 Including

» 140
109
101
97
92
88
87
84
82
80
80
79
21 infants that died not fed.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Breast
fed

51
30
19
14
10
7
5
5
1

Partly
breast
fed
1
1
1
1
2

2
3
2
1
1

Artificial Feeding
not re
ly fed
ported
64
77
82
82
81
81
80
77
78
78
79
78

3
1
................
................
................
................
................
................
................
................
................
................

190
G

CAU SAL FACTORS IN

I N F A N T M O R T A L IT Y

T a b l e 9 . — Prevalence o f breast and artificial feeding, by death or sur
vival o f mother during year after confinement; infants in eight cities

eneral

Months lived from birth to end of ninth
Months of artifi Feeding
not re
cial feeding
ported
(num
Number Per cent Number Per cent Number Per cent ber) 1
Months of breast
feeding

Death of mother at or with
in year after confinement
Total

Months of partly
breast feeding

192,212.5

110,384

57.4

33,904.5

17.6

47,842

24.9

839. 5
Mother died____________
Mother survived the year. 191,373.0

139
110,245

16.6
57.6

1 1 .0

1.3
17.7

686.5
47,155. 5

81.8
24.6

3
79

Total_________ ____

33,893. 5

Per cent not shown for “ not reported” group because not significant.
T a b l e 1 0 . — Mortality among infants whose mothers died at or within
one year after confinement as compared with all other infants, when influence of
differences in type o f feeding is eliminated; infants in eight cities

eneral

Deaths of infants of mothers who died at or with
in one year after confinement1

Type of feeding
Actual

Expected at aver
age rates for all
infants

Number
32

7.59

Ratio

Expected at aver
age rates for in
fants receiving the
same type of feed
ing

Number

4.22

13.06

Ratio

2.45

.37
.06
12.63

3
29
1 Excluding infant deaths in the first month.
2 Ratio of actual to expected.
G

eneral

able

1 1 .—

Causes o f death o f infants in Baltimore, according to whether
mother had had tuberculosis
Deaths of infants—

Cause of death
Total

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Whose
Whose
mothers mothers
had had had not
tuber
had tu
culosis berculosis

1,117

1,091

314
213
39
407
72
15

11
6

303
207
39
401
69

3
3

12
10

7
55

191

A P P E N D IX D .-----G E N E R A I* T A B E E S
G

T a b l e 1 2 . — Proportion o f births to mothers in Baltimore who^ had con
vulsions as a complication o f confinement, by term, and cause of infant’s death

eneral

Births to mothers who had convulsions as a compli
cation of confinement
Live births

Survival or death of infant and cause of death
Total

Total................................ ........................ —Live-born infants—
Who died within year............................................
1

* f

Still
births

Full
term

Prema
ture

Total

27
15

1
4

eneral

1 3 . — Infant mortality rates, by cause o f infant’s death and med
ical prenatal care of mother; live births in Baltimore

able

Infant deaths

All causes
Medical prenatal care of Live
births
mother

Gastric and
intestinal
diseases

Other
causes

Early
infancy

Respiratory
diseases

In
In
In
In
In
fant Num fant Num fant Num fant Num fant
Num mor
mor ber mor ber mor ber mor
ber tality ber tality
tality
tality
tality
rates1
rates1
rates1
rates1
rates1
Total.......... - ......... —- 10,797 1,117
No medical prenatal care... 5,120
Medical prenatal care-------- 5,660
17

580
531

103.5
113.3
93.8

314

29.1

213

19.7

407

37.7

183

16.9

178
133
3

34.8
23.5

119
94

23.2
16.6

190
215

37.1
38.0

93
89

18.2
15.7

i Not shown where base is less than 100.
G

eneral

Age of
mother

able

Monthly death rates, by age o f mother and month o f life;
in f ants in eight cities

In
fant
In
Live fant morbirths deaths tali' ty
rates

T o ta l- 22,967
Under 20----20-24........... 25-29_______
30-34_______
35-39............
.40 and over—
Not reported-

1 4 .—

1,584
6,879
6,618
4,231
2 ,6 8 8

958
9

2,555
215
753
671
443
340
131

1 1 1 .2

135.7
109.5
101.4
104.7
126.5
136.7

Monthly death rates
*d
d
o
£

ed
-4-3

•d
tj
GQ

•^
4-3

,d
4-3
d
<D

>
CD

IS
E"

dl
3<D

-d
3bJp

,g
g

>
CD

44.8

9.3

8 .1

8 .0

7.7

7.4

6.3

5.8

5.7

5.3

3.9

4.5

63.1
43.5
42.0
38.5
50.2
54.3

11.5
9.9
7.4
9.8

9.5
7.8
6.5
7.7
10.3
12.3

12.4

7.7
7.2
6.3

7.0
5.5
8.4
6.9
9.4
10.3

5.7
7.0
5.7
7.4
4.5
5.8

5.7
5.2

6.4
5.4
5.3

2.9
6.9
4.3
3.9
5.9
8.3

2.9
4.4
3.3
2.9
5.5

8.7
3.7
3.9
3.9
4.7
8.4

Not shown where base is less than 100.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

•d

1 0 .6

9.9

8 ,2
6 .6

7.0
10.4
7.9

1 0 .1

9.3
6 .8

6 .1

5.2
7.0
8 .1

6 .2

5.8
7.0

6 .0

192
G

CAU SAL FACTO RS IN

eneral

able

1 5 .—

IN F A N T

M O R T A L IT Y

A ge o f mother, by order o f birth; live births in eight cities
Livebirths
Age of mother

Order of birth
Total

Under
20

Total.
First....... ..........
Second________
Third_________
Fourth...............
Fifth..................
Sixth..................
Seventh_______
Eighth............
Ninth.................
Tenth and later.

20-24

30-34

25-29

22,967

1,584

6,879

6,618

4,231

6,230
4,954
3,328
2,481
1,767
1,263
921
677
470
876

1,227
311
39
5

3,125
2,196
968
412
133
32
9
3

1,349
1,621
1,407
1,043
624
339
138
68

399
599
609
694
631
480
353
226
126
114

40 and
over

35-39

Not reported

958
114
204
260
268
306
326
320
289
224
377

14
2
22
1
45 ............ ...
57
2
69
2
85
1
101 ..............
91 ................
98
1
376 ................

T a b l e 1 6 . — Relative mortality, by age o f mother, when influence o f order
o f birth, interval since preceding birth, and both factors together, is eliminated; live
births in eight cities and live births in-Baltimore

eneral

Infant deaths in eight cities

■Bixpeciea at
average rate
for births of
same order

Age of mother
Actual

Expected at average rates for
single births—
Ratio
of rate
in
speci
same order
Following pre Of
and following
fied
birth preceding
birth
group Actual ceding
after same
after same
to
interval
aver
interval
age
rate
(per
Num Ratio
Num Ratio
cent) 1
(per
(per
ber
ber
cent) 1
cent) 1

Ratio
of rate
in
speci
fied
group
to
aver
age
rate
(per
cent) 1

Num
ber

Ratio
(per
cent) 1

2,555 2,553.9

1 0 0 .0

764

764.0

1 0 0 .0

763.7

1 0 0 .0

132.0
106.9
95.2
90.4
97.5
92.3

1 2 2 .0

38
191

28.0
196.0
234.7
165.4
104.2
35.3
.4

135.7
97.4
85.6
93.7
127. 6
127.5

24.3
175.8
223.0
170.0
121.7
48.3

156.4
108.6
90.1
91.2
109.3
93.2

124.9
98.7
85.6
91.8
124.7
121.3

20-24..........................
25-29..........................
30-34 ................... .
35-39................. ........

215
753
671
443
340
131
2

1 Not

Infant deaths in Baltimore (single births)

162.9
704.2
705.1
490.3
348.6
141.9
.9

98.3
91.2
94.2
113.8
122.9

201

155
133
45
1

shown for “ not reported” group because not significant.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

193

A P P E N D I X D .— G E N E R A L T A B L E S

G e n e r a l T a b l e 17 .— Order o f birth, by interval since preceding birth 1 and age

o f mother; single live births in Baltimore second and later in order
Single live births second and later in order
Age of mother

Order of birth and interval since preceding
birth 1
Total

Under
20

20-24

25-29

30-34

35-39

40 and
over

Second birth.................................................. —

2,372

206

1,069

• 761

264

year.......................... .............- ..................
years________________________________
3 years............... ...........................................

703
863
339
466

114
80

376
454
154
85

161
257
121
221
1

44
58
40
122

7
13
9
33

3
5

1
2

1
1

Third birth....................... . . ................ ......... . .

1,436

460

577

249

103

year___ _____ ____________ _____ _____
years________________________________

381
618

23
3

178
194
64

9
25
13
56

1
6
10

131
224
92
127
3

211

458

288

107

101

33
19
45

2
6
2

1
2

220

309
7

Fourth b ir th ....................................... .............

1,095

year...... ......................................... ..........
years-------------- -------------- -------------------

242
416
205
225
v—7

795

3174
301
167
146
37

1
2

Fifth birth________________________________
1

year...... ............................................ ......

22
8
1

191
106
57
3

279

282

127

40
31

63
141
58
15

53
95
75
57

14
28
26
58

1
6

8
1

168

236

130

61
76

22
8
1

48
95
61
29
3

39
40
39

7
7
22

Eighth birth.......... ..........................................

8
1

168

140

114
149
82
76
5

2
1

-44
27
4

44
61
37
24

23
51
35
30

6
20
2

329

114

126

81
136

34
54
18
7

53
31
17
3

8
11

21
6
2

42
4
3

235
64
95
38
35
33
424
130
164
67
54
9

For definition of interval see p. 60.
J Including 2 births for which age of mother was not reported.
3 Including 1 birth for which age of mother was not reported.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

426

137
225
3132
98
4
Seventh birth...... .......................... ...................

Tenth and later births......................................

596

Ninth birth...... .......................................... ......

48
95

36
95
56
98
3

90
90

1
1

3
1

60
28
25
5
1
1

5
. 4
1

67
30
29
1

5
2

122

24
55
22
20
1

194
66

81
27
15
5

16
39
3
12
10

14
158
30
53
39
34
2

194
G

CAU SAL FACTO RS IN

IN F A N T M O R T A L IT Y

T a b l e 1 8 . — Proportion o f births following preceding birth at short
intervals, by order o f birth and age of mother; single live births in Baltimore

eneral

Per cent of live births following preceding birth at short intervals1
Age of mother

Order of birth
Total
Under
20

Second____________
Third_______
Fourth.................
Fifth_______
Sixth____
Seventh............
Eighth ____
Ninth______
Tenth and later___
1

29.6
26.6

55.3

2 2 .1

21.9
23.0
26.8
24.6
27.2
30.7

20-24

35:2
38.7
42.7
50.0

25-29

2 2 .6

36.3
57.1

11.3
8.7
9.3
1 1 .0

9. 2
16.4
17.5
19. 7
34.0

19.0

Not shown where base is less than 50. For definition of interval see p. 60!

eneral

T a b l e 1 9 . — Proportion o f premature births, by age o f mother, when
influence o f order o f birth is eliminated; live births in eight cities

Age of mother

Premature births

Ratio of
Expected actual to
expected
(per cent)

Actual

Total_______

1,158

1,158.4

1 0 0 .0

Under 2 0 ....... .........
20-24....................
25-29...............

137
368
314

107.4
399.0
316.4

127.6
92.2
99.2

eneral

Age of mother

Ratio of
Expected actual to
expected
(per cent)

Actual

30-34_____________
35-39..................
40 and over
Not reported

182
110

180.7
113.6
41.3

100.7
96.8
111.4

2 0 .— Relative mortality, by age o f mother, when influence of pre
maturity is eliminated; live births in eight cities

able

Infant deaths
Age of mother
Actual

Total.............
Under 2 0 . . .......
20-24....................
25-29.....................

Ex
pected

Infant deaths

Ratio of
actual to
expected
(per
cent) 2

2,555

2,554.9

1 0 0 .0

215
753
671

2 0 2 .0

106.4
97.2
92.3

\Hx? e?ted
2

40 and
over

35-39

16.7
15. 7
12. 5
18.8
20.3
26.2
29.8
46.7
44.8

2 1 .2

22. 7
22. 1

Premature births

30-34

774.8
727.3

Age of mother
Actual

30-34.................
35-39....................
40 and over_______
Not reported..........

443
340
131
2

Ex
pected

456.5
287.5
105.6
. 1 .2

averaSe rates for full-term and premature births, irrespective of age of mother.
Not shown for “ not reported” group because not significant.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Ratio of
actual to
expected
(per
cent) 2
97.0
118.3
124.1

195

A P P E N D IX D .-----G E N E R A L. T A B L E S
G

eneral

2 1 .—

Proportion o f confinements with instrumental delivery, by
age o f mother; confinements in Baltimore

able

Confinements—

Confinements—
With instrumental
delivery

Age of mother

With instrumental
delivery

Age of mother
Total

Total

Number Per cent1

Number Per cent 1
11,463

866

7.6

30-34........................

1 ,0 2 0
3 '461

84
279
24Ì

8 .2
8 .1

40 and over_______
Not reported______

3,178

25-29............... - ___

2,068
1,289
443
4

35-39

151

7.3

6 .8

5.2

7.6

i
1

Not shown where base is less than 100.

eneral

2 2 .—

Prevalence o f artificial feeding, by age o f mother and month
of infant’ s life; infants in eight cities

able

Infants surviving at begin
ning of sixth month

Infants surviving at begin
ning of third month

Age of mother
Total

Artificially fed
during third
month

Artificially fed
during sixth
month

Total

Under 20..................
20-24........................
25-29........................
30-34......... ..............
35-39........................
40 and over..............
Not reported---------

eneral

able

21,735

4,431

20.4

1,467
6,515
6,294
4,028
2,526
897

301
1,291
1,184
836
569
249

20.5
19.8
18.8

2 3 .—

Artificially fed
during ninth
month

Total

Number Per cent

Number Per cent
Total_______

Infants surviving at begin
ning of ninth month

6,145

29.0

20,812

7,268

34.9

1,424
6,365
6,172
3,929
2,451
873

433
1,867
1,740
1,085
730
289

1,398
6,253
6,048
3,853
2,400
852

516
2,265
2,076
1,277
825
307

30.4
29.3
28.2
27.6
29.8
33.1
12.5

36.9
36.2
34.3
33.1
34.4
36.0
25.0

2 1 ,2 2 2

2 0 .8

22.5
27.8
12.5

Number Percent

A ge of mother, by color and nationality o f mother; live
births in eight cities
Live births
Age of mother

Color and nationality of mother
Total

Under
20

20-24

25-29

30-34

35-39

40 and Not re
over ported

Total____________________ 22,967

1,584

6,879

6,618

4,231

2 ,6 8 8

958

White--------------- --------------------------- 21,510

' 1,403

6,400

6,270

3,986

2,534

911

1,064
339
77
30
24
40
67
38
63

3,976
2,424
404
309
190
401

3,451
2,819
410
399
303
176
397

2,017
1,969
274
275
237
174
226

201

210

111

697

924

671

1,187
1,347
182
177
191
129
131
80
457

407
504
78
43
98
67
43
29
146

181

479

348

245

154

Native-----------------------------------Foreign bom ---- ----------------------Italian_________ _____ - ........
Jewish------------- -----------------French-Canadian---------------German------- ----------------- -Polish............. ......................
Portuguese________________
Other_________ ____ _______

1 2 ,1 0 2

9,408
1,426
1,233
1,074
776
1,266
669
2,962

Colored............................................. .

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

1,457

221

6
1

196

CAU SAL FACTORS IN

I N F A N T M O R T A L IT Y

G e n e r a l T a b l e 2 4 .— Age o f mother, by earnings o f father and whether first or later

births; live births in seven cities
Live births
Earnings of father

Order of birth and age of
mother
Total

Less
than
$450

$450$549

$550$649

No
Not
$650- $850- $1,050- $1,250
and earn
re
$849 $1,049 $1,249 over
ings ported

T o t a l........... ............... 21,536

3,085

2,825

2,910

5,050

3,345

1,391

2,252

313

365

First births_____ ___________

5,908

638

658

776

1,464

1,054

447

697

Under 20____________ . . .
20-24..................................
25-29____________ ______
30 -34...............................
35-39..................................

1,160
2,949
1,295
377

184
185
319 > 342
100
98
24
27
7
4
3
2

200

287
777
291
82

163
540
269
65
16

42
281
245
98
29

32
35

111

403
117
41
15

212

133
31
15

40
31
4

5
2

1
2

Second and later births_____

15,628

2,447

2,167

2,134

3,586

2,291

944

1,555

228

Under 20..........................
20-24..................................
25-29..................................
30-34........................... .
35-39..........................
40 and over.......................
Not reported___________

343
3,485
4,941
3,585
2,397
870
7

60
578
663
428
328
109

65
524
642
491
289
123

64
860
1,204
783
476
198

35
485
757
556
341
117

7
194
497
468
300
89

59
63
44
45
9

57
80
69
42

563
721
503
414
153
5

165
314
243
162
52

276

G e n e r a l T a b l e 25 .— Age o f mother, by per capita income from father’s earnings;

live births in seven cities
Live births

Per capita income from father’s earnings

Age of mother
Total

Less
than $50

$50-$99

18,587

227

2,948

6,900

8 ,0 0 0

512

20-24............................. ...............................
25-29__________________________________
30-34.............................................................
35-39_________ ______ __________________

1,392
5 , 765
5,325
3,256
2,083
. 758

215
739
805
805
376

973
3,490
2,260
873
349
53

64
244
152
36
15

Not reported-_______ __________________

4
41
106
75

348
1,816
2,170
L501
'808
253
4

and
$100-$199 $200-$399 $400
over

1 Excluding births in earnings groups “ $1,250 and over,” “ no earnings,” and “ earnings not reported,
and 19 infants for whom the number in the family was not reported or who lived in institutions.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

197

A P P E N D I X D .— G E N E R A L T A B L E S

General T able 26.-—Monthly death rates, by order o f birth and jnonth o f life;
infants in eight cities

•

Eighth

Ninth

9.3

8 .1

5.8

5. 7 5.3

3.9 4.5

53.6 8.3 5.5 6 . 0 5.9 4.9 4.5 4.2
39.2 8 . 8 7.6 8 . 1 5.4 6.3 4.8 4.6
41.5 9.1 6 . 6 8 . 6 7.4 7.8 6 . 2 4.6
35.9 8.4 7.6 5.9 8.5 6.9 9.1 7.9
40.2 8 . 8 6.5 1 2 .0 13.3 10.4 7.4 5.0
39.6 9.1 13.3 9.3 6 .0 9.4 9.5 11.3
40.2 12.4 19.5 7.0 14.1 11.9 4.8 1 2 .1
48.7 9.3 9.4 9.5 16.0 9.7 4.9 4.9
46.8 15.6 11.3 11.5 7.0 11.7 9.5 9.5
68.5 18.4 15.0 13.9 1 1 .6 13.0 13.2 9.3

4.8 4.6
4.6 4.2
5.6 3.6
6 . 6 5.3
6.9 7.0
3.5 7.1
8 . 6 8.7
1 1 .6 8.4
7.2 7.3
9.4 9.5

2 . 0 4.6
3.8 2 . 2
4.3 4.0
5.4 6.7
2.5 5.1
8 . 0 3.6
___ 6.3
8.4 3.4
1 2 .2 7.4
5.5 9.7

6 j 230

First ........................
Second.......................Third. ................. .
Fourth........................
Fifth...........................

4,954
3,328
2,481
1,767
1,263
'921
677
470
876

Seventh......................
Eighth.......................
Ninth..........................
Tenth and later______

210

155
126
92
69
159

Sixth

7.7

7.4 ’ 6.3

| Tenth

Fifth

8 .0

Eleventh

Third

44. 8

104.7
95.7
104.6
108.8
118.8
122.7
136.8
135.9
146.8
181.5

P
«S
P4
H

Seventh

Second

1 1 1 .2

652
474
348
270

Order of birth

Fourth

First

Total_________ 22,967 2,555

Live birth

Infant mi
ity rat<

1 Twelfth J

Monthly death rates
©
'Ö

General T able 27.— Relative mortality, by order o f birth, when influence of
prematurity and plurality o f birth is eliminated; live births in eight cities
Infant deaths

Infant deaths

Order of birth
Actual

Fourth.......... ..........

Ratio of
actual to
Expected expected
(per
cent)

2,555

2,555.1

652
474
348
270

747.4
547. 3
358.6
262.3

1 0 0 .0

87. 2
8 6 .6

97.0
102.9

Order of birth
Actual

Fifth...................... .
Seventh...................
E ig h th .:................
N in th ....................
Tenth and later___

210

155
126
92
69
159

Ratio of
actual to
Expected expected
(per
cent)
182.7
136. 3
96.9
73.5
52.4
97.7

114.9
113.7
130.0
125.2
131. 8
162.7

General T able 28.— Relative mortality, by order of birth, when influence o f
interval since preceding birth and when influences of both interval since preceding
birth and age o f mother are eliminated; jingle live births in Baltimore second and
later in order
Infant deaths

Order of birth
Actual

Expected at aver
age rate for all
single births sec
ond and later in
order

Expected at average rate—

For same interval

For same interval
and age of mother

Number

Ratio
(per
cent )l

Number

Ratio
(per
cent )*

Number

Ratio
(per
cent y

Total..................................

764

763.9

1 0 0 .0

763.6

1 0 0 .1

765.0

99.9

Second___________ _______ ___
Third...........................................
Fourth........................... ...... .......
Fifth................. ................ ..........
-Sixth................. ..........................
Seventh.......................................
Eighth and later.........................

208
126
104
80
57
47
142

235.1
142.3
108.5
78.8
59.1
42.2
97.9

88.5

238.9
142.2
105.9
77.0
58.0
42.3
99.3

87.1

235.7
135.4
102.7
73.7
57.2
45.7
114.6

93.1
101.3
108.6
99.7

i Ratio of actual to expected.

96515°—25f----- 14

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

8 8 .6

95.8
101.5
96.5
111.3
145.0

8 8 .6

98.2
103.9
98.3
111 . 1
143.0

8 8 .2

1 0 2 .8

123.9

198

C A U SAL FACTORS IN

IN F A N T

M O R T A L IT Y

General T able 29.— Proportion of confinements with instrumental delivery, by
order o f birth; confinements in Baltimore
Confinements—

. Confinements—

With instrumental
delivery

Order of birth

With instrumental
delivery

Order of birth

Total

Total
Number

First_____________
Third____________
Fourth....................
G en eral T able

Per cent

Number Per cent

11,463

866

7.6

870

4.3

3,050
2', 532
1,580
i; 197

510
132
67
50

16. 7
5.2
4.2
4.2

467
361
261
480

18
16
9
13

3.9
4.4
3.4
2.7

Eighth.
N inth..__________
Tenth and later___

30.— Prevalence o f artificial feeding, by order o f birth and month
o f life; infants in eight cities
Infants surviving at
beginning of third month

Order of birth
Total

Artificially fed
during third
month

Infants surviving at
beginning of sixth month
Artificially fed
during sixth
month

Total

Number Per cent
Total.........

Infants surviving at
beginning of ninth month

Total

Number Per cent

Artificially fed
during ninth
month
Number Per cent

21,735

4,431

20.4

2 1 ,2 2 2

6,145

29.0

20,812

7,268

34.9

5,854
4,716
3,166
2,371
1,681
1,203
865
637
443
799

1,259
948
580
444
325
234
169
136
92
244

21.5

6,755
4,624
3,089
2,317
1,628
1,169
828
617
428
767

1,823
1,370
847
618
414
297

31.7
29.6
27.4
26.7
25.4
25.4
25.4
28.2
25.2
37.1

6,680
4,551
3,030
2,266
1,588
1,134
803
606
415
739

2,240
1,601
1,036
731
472
334
233

39.4
35.2
34.2
32.3
29.7
29.5
29.0
33.2
27.5
41.4

First.........................
Second.... ........ ........
T h ird.....................
Fourth ...................
Fifth........................
S ixth......... ............
Seventh__________
Eighth. ...............
Ninth____________
Tenth and later___

2 0 .1

18.3
18.7
19.3
19.5
19.5
21.4
2 0 .8

30.5

210

174
108
284

201

114
306

General T able 31.— Order o f birth, by color and nationality o f mother; live births
in eight cities
Live births
Color and nationality of mother
White
Order of birth
Foreign born

Total
Total Native

TotaL___
First.................
Second________
Third___ iJi___
Fourth— ^ .....
Fifth.................
Sixth_________
Seventh_______
Eighth.............
Ninth...............
Tenth and later

22,967 21,510
6,230
4,954
3,328
2,481
1,767
1,263
921
677
470
876

1 Including

1 2 ,1 0 2

Total

Ital Po
ian lish

Jew FrenchGer Portu Other
ana man
ish Cdian
guese

19,408 1,426 1,266 1,233 • 1,074

6,962 4,054 3 1,908
4; 6 6 6 2,915
1,751
3,116 1,682 »1,434
2,304 1,157
1,147
722
909
1,631
1,164
639
525
845
337
608
249
609
360
172
261
433
289
780
491

234
234
226
192
158
116
97
55
44
70

253
225
188
160
132
77
71
56
42
62

235
255
204
133
136
81
68

48
30
43

2 births for which nationality of mother was not reported.
3Including 1 birth for which nationality of mother was not reported.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

202

179
122

114
94
77
58
59
38
131

Col
ored

776

669

2,962

1,457

149
157
124
91
63
52
38
26
25
51

127

707
590
468
358
255
194
140
95
67

268
288

111
101

99
71
42
36
21

15
46

212

177
136
99

199

A P P E N D IX D .-----G E N E R A L T A B L E S
G

eneral

able

3 2 .—

Order o f birth, by earnings o f father; live births in seven cities
Live births
Earnings of father

Order of birth
Total

Less
than
$450

$450$549

$550$649

No
Not
$650- $850- $1,050- $1,250
and earn
re
$849 $1,049 $1,249 over
ings ported

T o ta l............................ 21,536

3,085

2,825

5,908
638
4,681 ' 570
442
3,115
2,302
371
287
1, 632
1,172
201
847
168
622
118
437
103
820
187

First........................................
Second.....................................
Third.......................................
Fourth..... ..............................
Fifth....... .................................
Sixth_________________ ____
Seventh___________________
Eighth.....................................
Ninth____________ ______ _
Tenth and later......................
G

eneral

able

3 3 .—

2,910

5,050

3,345

1,391

2,252

313

365

658 '
586
396
332
235
177
141

776
594
386
344
230
179

697
590
335

85
63
42
31

89
78
53
34
33

106
61
113

1,054
784
515
295
230
142
108
77
46
94

447
307
209
145

102

1,464
1,109
737
528
383
256
188
119
96
170

121

58
140

222

127
107
55
45
27
47

63
42
29
25
38

14
14

10
12
11
12

Order o f birth, by per capita income from father’ s earnings;
live births in seven cities 1
Live births 1
Per capita income from father’s earnings

Order of birth
Total

Total____

18,587

First....... .........
Second________
Third_________
Fourth..........
Fifth.................
Sixth_________
S eventh....___
Eighth________
Ninth...............
Tenth and later

6,026
3,947
2,683
2,014
1,452
1,018
768
650
389
740

Less
than $50

$50-$99

227

2,948

6,900

8,000

512

611
1,485
1,398
1,217
808
536
360
209
126
150

3,943
2,412
1,040
356
148
55
19
11
6
10

461
40
9

and
$100-$199 $200-$399 $400
over

235
441
494
424
365
302

3
24
28
47
124

210

456

i Excluding births in the earnings groups “ $1,250 and over,” “ no earnings,” and “ earnings not
reported,” and 19 infants in earnings groups under $1,250 for whom number in family was not reported or
who lived in institutions.
able

3 4 .—

Monthly death rates, by interval since preceding birth 1 and
month o f life; infants in Baltimore

Interval since preceding birth 1

Infant mortality
rate

Infant deaths

eneral

Live births

Monthly death rates 2

*d
*d
pi
Q
O A
m
CQ e»

H
Ì*4

Total___ ______________ 10,797 1,117 103.5 44.2 6.3
2 ,8 6 8
First births............... ..........
Second and later births_______ 7,929

„

Interval 1 year___________
Interval 2 years...................
Interval 3 years__________
Interval4 years and over..
Interval not reported_____
1

2,072
2,950
1,364
1,496
47

o
N

6 .1

A
."S
oä

d
-U
g
è

A
-M d
A
bû ta
H

A
©
e<

d
g

£
Eh

7.0 7.6 5.6 5.6 5.2 5.0 4.3 5.0

272 94.8 52.3 4.4 4.4 3.7 6.7 3.8 2 . 6 4.5 3.0 4.6 2.3 5.7
845 106.6 41.2 7.0 6 . 8 6.9 7.1 8.9 6.7 6 . 0 5.9 5.1 5.0 4.8
304
291
118
127
5

l£or definition of interval see p. 60.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

6 .1

A
4m
-3
d A

146.7
98.6
86.5
84.9

51.2
37.3
36.7
38.1

7.6 13.3 9.9 6.3 13.7 1 1 .2 8 . 1 1 2 .0
7.7 6.3 6.4 7.5 6.9 6 . 2 6 . 6 3.0
2.3 4.6 5.4 7.7 8.5 7.0 3.2 3.2
9.0 2 . 8 5.6 7.1 7.1 1.4 4.3 6.5

7.7 9.5 6 . 2
5.2 6 . 0 4.9
4.0 0 . 8 6.4
2.9 1.5 1.5

Not shown where base is less than 100.

200
G

CAUSAL FACTORS IN IN F A N T MORTALITY

eneral

able

3 5 . — Per cent o f 'premature births, by order o f birth and interval
since preceding birth 1; live births in Baltimore

Per cent of premature births
Interval since preceding birth 1

Order of birth
Total

One
year
Total.....................................................................
First..................................................................
Second.............. ...................................
Third___________________________
Fourth______________ _____
Fifth__________________
Sixth_____________
Seventh______________________
Eighth and later...............................................
1

5.5

Two
years

Three
years

Four
years

6.4

3.6

3.7

7.2
6.5
4.7
4.6
5.0
5.9
7.7

40
3.8

4 ft

2 .8

3.8
2.3
3.6
2.4
6.5

4.6

8 .0

5. 3
4.7
3.6
2.7
4.4
3.6
5.6

2 .2

1.9
5.7
2 .0

3.7

5.9
3.5
2 .0

1.9
4.9
5.3

For definition of interval see p. 60.

G e n e r a l T a b l e 3 6 . — Prevalence of artificial feeding, by interval since preceding

birth 1 and month o f life; infants in Baltimore
Infants surviving at be Infants surviving at be Infants surviving at be
ginning of third month ginning of sixth month ginning of ninth month
Artificially fed
during third
month

Interval since preceding
birth 1
Total

Artificially fed
during sixth
month
Total

Num
ber

Per
cent

Artificially fed
during ninth
month
Total

Num
ber

Per
cent

Num
ber

Per
cent

T otal........... ...............

10,255

2,006

19.6

10,059

2,725

27.1

9,871

3,153

31.9

First births___________ ____
Second and later births_____
Interval 1 year................
Interval2 years..............
Interval3 years........ ......
Interval 4 years and over.
Interval not reported___

2,706
7,549
1,951
2,818
1,311
1,426
43

568
1,438
470
436
225
298
9

2 1 .0

2 ,6 6 6

19.0
24.1
15. 5
17.2
20.9

7,393
1,894
2,764
.1,288
1,404
43

801
1,924
606
614
300
392

30.0
26.0
32.0

2,637
7,234
1,832
2,710
1,264
1,386
42

966
2,187
677
713
343
443

36.6
30.2
37.0
26.3
27.1
32.0

2 2 .2

23.3
27.9

For definition of interval see p. 60.

eneral

able

3 7 .—

Interval since preceding birth,1 by color and nationality o f
mother; live births in Baltimore
Second and later births: Interval since preceding
birth 1

Color and nationality of mother

Live
births

First
births
One
year

Two
years

Three
years

Four
years
and over

Not re
ported

Total...........................

10,797

2 ,8 6 8

2,072

2,950

1,364

1,496

White____ __________
Native___________________
Foreign b o r n ..____ _______
Italian_________ _____
Jewish...................... .
French-Canadian_____
G erm an........................
Polish............... ........
Other________________

9,492
6,739
2,753
412
961
3
318
625
434

2,637
2,133
504
56
168

1,712
1,174
538

2,545
1,669
876
146
284

1,197
810
387
55
160

1,361
930
431
39
215 -

61
146

93
231

i
4

121

46
81
45

58
53

Colored_______ ________ _____

1,305

231

360

405

167

135

For definition of interval see p. 60.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

110
111

111

130

47
40
23
17
\ 5
) 4

201

A P P E N D I X D .-----G E N E R A L T A B L E S
G

eneral

able

Interval since 'preceding birth,1 by earnings o f father; live
births in Baltimore second and later in order

3 8 .—

3 9 .—

Interval since preceding birth,1 by per capita income from
father’s earnings; live births in Baltimore
Live births 2
**•

Per capita income from
father’s earnings

First
births

Total

Total................................ _
Less than $50____________
$50-$99...........................
$100-$199______ _____ ___
$200-$399................. ........
$400 and over............. ...........

Interval since preceding birth
One
year

Two
years

Three
years

9,149

2,382

1,819

2,576

1,126

104
1,498
3,394
3,919
234

26
356
842
582
13

42
606
1,208
706
14

18
299
541
264
4

4
290
1,889
198

Four
and over

Not
reported

1,204

222

U
18
13

495
465

For definition of interval see p. 60.
JExcluding births in the earnings groups “ $1,250 and over,” “ no earnings,” and “ earnings not re
ported ; also 6 infants for whom the number in the family was not reported or who lived in institutions.
1

T a b l e 4 0 . — Prevalence o f breast and artificial feeding when mother
became pvegnant) infants in Baltimove whose mothevs became pvegnant dwring
first year o f infant’s life

eneral

Live births to mothers pregnant during first year of infant’s life 1
Months in which mothers became pregnant

Ninth

Breast__________ _
Partly breast.........
Artificial
"Not reported_____

240
234
697

160

152

173

145

139

110

3
4

36
23
93

17
5

10
2

38
27
80

37
32
70

14
45
51

68
1

10
112

125

Twelfth

Eighth

Fourth

Seventh

Total_______ 1,172

Third

.g
s

Second

A
5

First

Fifth

Total

Eleventh

Type of feeding

14
40
34

27
30

. 1 Omitting 28 cases in which infants died in the same month that mother became pregnant, and 60 cases
in which the infant survived the year but the month o f infant’s life during which mother became pregnant
was not reported. In 18 other cases, also omitted, in which the infant died it was not reported whether
the mother s pregnancy commenced before or after the infant’s death.

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Federal Reserve Bank of St. Louis

202
G

CA U SAL FACTO RS IN

IN F A N T M O R T A L IT Y

T a b l e 4 1 . — Cause o f death, hy month o f life in which death occurred;
deaths among infants in eight cities whose mothers became pregnant in some
preceding month

eneral

Deaths from specified causes of infants whose mothers became
pregnant in some preceding month
Gastric
and
intesti
nal
diseases

Respira
tory
diseases

2
1
1

Month of life
All
causes

T o t a l________________________ _
Third_________________________________

Fifth__________________________________

Eighth________________________________

6
6

11
12
11

8
6

Epidemic
and other
commu
nicable
diseases

Other
causes

6
1

9
4

7
7
9

Early
infancy

1
1
1
1
2

7
’

2
1
1

1
1
1

T a b l e 4 2 . — Type o f feeding during months lived to end o f ninth and
after commencement o f mother’s subsequent pregnancy; infants in eight cities
whose mothers became pregnant during infant’ s first year

eneral

Months lived from be
ginning of mother’s
subsequent
p reg
nancy to end of ninth
Type of feeding
Number

Artificial_________________________________________________________________
Not reported....... ...................................................................... .............................
G

Per cent
distribu
tion

2,709

1 0 0 .0

307.0
267.5
2,132. 0
2.5

11.3
9.9
78.7
0 .1

T a b l e 4 3 . — Type o f feeding after beginning o f mother’ s subsequent preg
nancy, by month o f life; infants in Baltimore whose mothers became pregnant
during first year o f infant’s life

eneral

Infants surviving at beginning of each specified month whose mothers had pre
viously become pregnant
Month of life

Breast fed during
specified month

Total

Partly breast fed
during specified
month

A rtificia lly fed
during specified
month

Number Percent1 Number Per cent 1 Number Per cent 1
Second...
Third___
F o u r th Fifth____
Sixth___
Seventh._
E ig h t h Ninth___
Tenth___
Eleventh.
Twelfth..
1 Not shown where base
2 Per cent not shown for

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

3
7
19
41
41
44
49
52
47
40

48
138
294
436
602
740
870
969
1,045

3
13.8
13.9
■ 9.4
7.3
6 .6
6 .0

4.9
3.8

1
2
6

16
40
58
85
103
124
145

4.3
5.4
9.2
9.6
11. 5
1 1 .8
1 2 .8

13.9

is less than 1 0 0 .
“ not reported ” group because not significant.

39
112

236
355
500
606
715
798
860

81.2
80.3
81.4
83. 1
81.9
82. 2
82.4
82.3

Feeding
not re
ported
(num
ber) 2

203

A P P E N D IX D .— G E N E R A L T A B L E S
G

eneral

able

4 4 .—

Cause o f death, hy term; infant deaths in eight cities
Infant deaths

Cause of death
Full
. term

Total

Premature

Period of
gestation
not
reported

All causes.,_______________________

2,555

1,917

626

Gastric and intestinal diseases_____ ______

743

689

Diseases of the stomach______________
Diarrhea and enteritis.____ . . . . _______

24
719

19
670

5
46

450

414

Acute bronchitis____________ ______ _
Broncho-pneumonia_________________
Pneumonia__________________________

70
267
113

57
244
113

Malformations__________________________
Early infancy.._________________________
Epidemic and other communicable diseases.

99
830
162

79
356
144

Measles...................................................
Scarlet fever______________ __________;
Whooping cough____ ________________
Diphtheria and croup..............................
Influenza____________________________
Dysentery.... .............. ............ ..............
Erysipelas...............— ........... ............ ..
Tetanus,_________________ __________
^Tuberculosis of the lungs............... ........
Tuberculous meningitis..........................
Other forms of tuberculosis............... .
Syphilis_________________ _________ _

12
1

11
1

Respiratory diseases___ !______ _________ _

9
5

7
5

469
17

11
1
11

23
3
23

23
3
15

External causes__________________________
Diseases ill defined and unknown_________
Other causes_________;________________.__

14
58
199

13
47
175

Meningitis____ _______________ ______
Convulsions_________________________
Organic diseases of the heart__________
Other______________ '________________

33
45
9

32
36

eneral

able

4 5 .—

5
1

12
1
12

112

1
10

Monthly death rates, hy month o f life and term; infants in
eight cities
Infants surviving at beginning of specified month
Full term 1

Month of life
Total

First____
Second...
Third___
Fourth..
Fifth___
Sixth___
Seventh..
Eighth...
Ninth__
Tenth__
Eleventh
Twelfth..

21,809
21,291
21,114
20,954
20,789
20,634
20,488
20,363
20,255
20,143
20,044
19,968

Deaths
during
month
518
177
160
165
155
146
125
108
112

99
76
88

Premature
Monthly
death
rates
23.8
8.3
7.6
7.9
7.5
7.1
6 .1

5.3
5.5
4.9
3.8
4.4

Including 50 infants for whom the period of gestation was not reported.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Total

1,158
648
621
606
598
588
578
571
557
550
540
536

Deaths
during
month

Monthly
death
rates

510
27
15

440.4
41.7
24.2
13.2
16.7
17.0

8
10
10

7
14
7
10

4
4

1 2 .1

24.5
1 2 .6

18.2
7.4
7.5

204
G

eneral

CAUSAL FACTORS IN IN FAN T MORTALITY
T

able

4 6 .— Infant mortality and stillbirth rates, by 'period o f gestation
and single and plural births; births in eight cities

Infant deaths
Period of gestation and single and
plural births

Full term......... ........... ................. ___ __

Total
births

Live
births

Number

Infant
mor
tality
rates i

Stillbirths

Number

Per
cent 1

23,780

22,967

2,555

1 1 1 .2

813

3.4

22,241
1,488
145
1,336
7
51

21,759
1,158
' 145
1,007

1,917
626
137
483

8 8 .1
540. 6

482
330

2 .2
2 2 .2

329

24.6

6
12

23,223

22,438

2,363

105.3

785

3.4

21,818
1,354
119
1,228
7
51

21,352
1, 036
119
911

1,801
550

84.3
530.9
941.2
474.2

466
318

2 .1

23.5

317

25.8

6
12

557

529

192

362.9

5.0

423
134
26
108

407

116
76
25
51

285.0
622.9

16
12

3.8
9.0

1 1 .1

122

26
96

112

432

944.8
479.6

1
1

Not shown where base is less than 100.

eneral

4 7 . — Proportion o f births to mothers who died at or within one
year after confinement, by term; live births in eight cities

able

Live births—

Term
Total

T o mothers who
died at or within
one year after
confinement
Number Per cent

1 Including

50 births for which the period of gestation was not reported.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

22,967

140

0 .6

21,809
1,158

112

.5
2.4

A P P E N D IX

D . ------G E N E R A L

205

TABLES

G e n e r a l T a b l e 48 .— Type o f feeding, by month o f life and period o f gestation;

infants in eight cities
Full-term infants1
Feeding
not re
ported
Number Per cent Number Percent Number Per cent (num
ber) 3
Breast fed

Month of life
Total

First........................................ »21,604
21,291
Second____________________
Third.....................................- 21,114
Fourth.................................... 20,954
F ifth ...................................... 20,789
Sixth................. ....................... 20,634
Seventh................................... 20,488
Eighth................. .................
20,363
Ninth________ ____________
20, 255
Tenth..................................... 20,143
Eleventh_____ ____________
20,044
Twelfth_______ _______ ____ 19,968

18,840
16,753
15,155
13, 216
11,990
10,733
8,448
7,173
5,715
i 168
3,229
2,699

Partly breast fed

87.2
78.7
71.8
63.1
57.7
52.0
41.2
35.2
28.2
20.7
16. 1
13.5

657
1,258
1,745
2,612
3,256
4,021
5,700
6,555
7,552
8,419
8,873
8,958

Artificially fed

3.0
5.9
8.3
12.5
15.7
19.5
27.8
32.2
37.3
41.8
44.3
44.9

2,099
3,270
4,205
5,116
5,533
5,870
6,331
6,626
6,981
7,547
7,933
8,304

9.7
15.4
19.9
24.4
26.6
28.4
30.9
32.5
34.5
37.5
39.6
41.6

8
10

9
10
10
10

9
9
7
9
9
7

Premature infants
Month of life

Breast fed
Total

First........ ........... ...................... .
Third___________________ ____
Fourth.... ................ ...... .............
Fifth..................................... .
Seventh__________ ___________
Ninth____ ___________________
Tenth__________ ____ _______ _

4 818

648
621
606
598
588
578
571
557
550
540
536

Partly breast fed

Artificially fed

Number Per cent Number Per cent Number Percent
598
425
354
300
273
236
193
170
138
87
56
44

73.1
65.6
57.0
49.5
' 45.7
40.1
33.4
29. 8
24.8
15.8
10. 4
8 .2

29
36
41
56
61
77

3.5
5.6

188
187
226
250
264
275
284
285
287
298
302
311

6 .6

9.2
1 0 .2

13.1
17.5
20.3
23. 7
30.0
33. 7
33.8

101

116
132
165
182
181

1 Including 50 infants for whom the period of gestation was not reported.
3 Per cent not shown for “ not reported” group because not significant.
3 Excluding 205 infants who died not fed.
4 Excluding 340 infants who died not fed ; including 3 for whom feeding was

23.0
28.9
36.4
41.3
44.1
46.8
49.1
49.9
51.5
54.2
55.9
58.0

not reported.

G e n e r a l T a b l e 49 .— Prevalence o f breast and artificial feeding during first nine

months, by term and single and plural births; months lived by infants in eight
cities
Months lived from birth to end of ninth 1
Term and single
and plural births

Months of breast
feeding
Total
Number

Months of artificial Type of
feeding
feeding
not re
ported
Per cent Number Per cent (num
ber) 3

Months of partly
breast feeding

Per cent Number

Total_______ 192,212.5

110,384.0

57.4

33,904.5

17.6

47,842.0

24.9

82.0

Full term 186,761.5
P re m a ture___
5,451

107,761.5

57.7

33,266.5

17.8

45,653.0

24.4

80.5

2,622.5

48.1

638.0

11.7

2,189.0

40.2

1.5

Single births........... 188,689. 5

109,182. 5

57.9

33,173.5

17.6

46,251. 5

24.5

82.0

106,715. 5
2,467.0

58.1
49.8

32,602. 5
571.0

17.7
11.5

44,334. 5
1,917.0

24.1
38.7

80.5
1.5

Full term.........
Premature.......

183,733
4,956. 5

Plural births______

3,523

1 , 2 0 1 .5

34.1

731.0

20.7

1,590.5

45.1

Full term.........
Premature____

3,028. 5
494.5

1,046.0
155.5

34.5
31.4

664.0
67.0

21.9
13.5

1,318. 5
'272.0

43. 5
55.0

1 In case of death the infants were considered to have lived on the average one-half the month in which
they died.
3 Per cent not shown for “ not reported” group because not significant.

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Federal Reserve Bank of St. Louis

206
G

eneral

CAUSAL FACTORS IN
T

able

5 0 .—

IN F A N T M O R T A L IT Y

Proportion o f births fifth and later in order, by term; live
births in eight cities
Live births—
Fifth and later in
order

Term
Total

Number
Total__________ _________________
Full term________________________
Premature_______ ____ ___ ____

Per cent

22,967

5,974

26.0

* 21,809
1,158

5,747
227

26.4
19.6

1 Including 50 births for which the period of gestation was not reported.
G

eneral

5 1 . — Proportion o f births to mothers under 20 and to those 85
years o f age and over, by term; live births in eight cities

able

Live births—
T o mothers under
20, and 35 and over

Term
Total

Number

Per cent

Total______ _______ _____ ______ ..

22,967

5,230

22.8

Full term__________________ ____
Premature..____ _______ ______________

121,809
1,158

4,937
293

22.6
25.3

1 Including 50 births for which the period of gestation was not reported.
G

eneral

able

5 2 . — Proportion o f births following preceding births after short
intervals,1 by term; live births in Baltimore

Live births second and later
in order—
Term
Total

Following preceding
birth after short
interval1
Number Per cent

Total....................................................
Full term_____ ___________________ _____
Premature______ ____ ______ ____ _

7,929
»7,568
361

1 For definition of interval see p. 60.
1 Including 10 births for which the period of gestation was not reported.

1Including Freneh-Canadian, Polish, Portuguese, “ other foreign born,” and colored.
» Including 50 births for which the period of gestation was not reported.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

2,072
1,940
132

26.1
25.6
36.6

207

A P P E N D IX D.-— G E N E R A L T A B L E S
G

eneral

able

5 4 .—

Proportion o f births in fam ilies in which father earned less
than $650, by term; live births in seven cities
Live births—
In families in which
father earned less
than $650

Term
Total

Number Per cent
21,536

9,133

42.4

» 20,425
1,111

8,698
435

42.6
39.2

1 Including 47 births for which the period of gestation was not reported.
G

eneral

55.^-Proportion o f births to mothers employed away from home
during pregnancy, by term; live births in eight cities

able

Live births—

Term
Total

T o mothers em
ployed away from
home d u r i n g
pregnancy
Number

Per cent

22,967

3,084

13.4

121,809
1,158

2,897
187

13.3
16.1

i Including 50 births for which the period of gestation was not reported.
G

eneral

5 6 . — Death in infancy and survival o f twins in pairs, by char
acter o f birth- and period o f gestation; twins in eight cities

able

Pairs of twins
One a live birth

Both live births
Character of birth and period of gestation
Both
sur
vived
the
year

Total

One
sur
vived
the
year,
one
died

Both
died

1 19

14
6
3
2

13
1
1

1
4
2
2

134

247

134

Both full term______ ._______
One full term, one premature.
Both premature. . . . . . ______
Less than 7 months_____
7 months and over_____ ..

191
1
55
ii
44

116
1
17
1
16

29
10
19

One a live birth________ , . _____ _
Full term........... ....................
SfTPremature;________
...
Less than 7 months_____
7 months and over.......... .
Both stillbirths.................... —

1Including 5 cases in which the stillborn twin was of less than 7 months’ gestation.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Died

271

Both live births...................... »—

Total________________

Sur
vived
the
year

Both
still
births

208
G

CAU SAL FACTORS IN

eneral

able

5 7 .—

I N F A N T M O R T A L IT Y

Monthly death rates, by month o f life and single and
'plural births; infants in eight cities
Infants surviving at beginning of specified month
Plural births

Single births
M onth of life
Total

First...... .................................. ..........................
Second...... .............................................. ..........
T h i r d ............. .......... ................................ .
Fourth...................... ............................. ..........
Fifth_____________________________________
Sixth _ _________________________________
Seventh . __________ ______. . . . .................
Eighth___________________________________
N in th .. ____________________________ ____
T e n t h ________ _ . _____________ .._______
Eleventh . . _____________________________
Twelfth__________________________________

eneral

able

5 8 .—

Deaths
during
month

22,438
21,501
21,315
21,157
20,999
20,845
20,693
20,568
20,464
20,353
20,246
20,166

937
186
158
158
154
152
125
104
111
107
80
91

Monthlydeath
rates

Total

41.8
8.7
7.4
7.5
7.3
7.3
6.0
5.1
5.4
5.3
4.0
4.5

Deaths
during
month

529
438
420
403
388
377
373
366
348
340
338
338

M onthly
death
rates

91
18
17
15
11
4
7
18
8
2

172.0
41.1
40.5
37.2
28.4
10.6
18.8
49.2
23.0
5.9

3.0

Type o f feeding, by month o f life and single and plural
births; infants in eight cities
Infants: Single births

Month of life

Breast fed

Partly breast fed

Number Per cent Number Per cent Number
First_____>._________
Second_____________
Third______________
Fourth_____________
Fifth_____ _________
Sixth______________
Seventh_____
. ..
Eighth_____________
Ninth______________
Tenth_____ ________
Eleventh_______ . . .
Twelfth____________

» 21,942
21,501
21,315
21,157
20,999
20,845
20j 693
20,568
20,464
20,353
20,246
20,166

19,132
16,962
15,349
13,393
12,151
10,871
8i 562
7,275
5,797
4,214
3,247
2,709

87.2
78.9
72.0
63.3
57.9
52. 2
41.4
35.4
28.3
20.7
16:0
13.4

638
1,226
1.706
2,579
3,228
4,009
5i 710
6,577
7,588
8,482
8,952
9,040

2.9
5.7
8.0
12.2
15.4
19.2
27.6
32.0
37.1
41.7
44.2
44.8

Feeding
not
reported
(num
Per cent
ber) 3

Artificially fed

Total

2,161
3,303
4,251
5,175
5,610
5,955
6|412
6,707
7,072
7,648
8,038
8,410

9.8
15.4
19.9
24.5
26.7
28.6
31.0
32.6
34.6
37.6
39.7
41. 7

11
10
9
10
10
10
9
9
7
9
9
7

Infants: Plural births

Month of life

Breast fed

Partly breast fed

Artificially fed

Total
Number Per cent Number Per cent Number Per cent
First.______________
Second......... ..........
Third______________
Fourth_____________
Fifth....... ...........
Sixth_______________
Seventh................. .
Eighth______ _______
Ninth____ __________
Tenth....... ..................
Eleventh___________
Twelfth.......................

3480
438
420
403
388
377
373
366
348
340
338
338

306
216
160
123
112
98
79
68
56
34
31
27

63.8
49.3
38.1
30.5
28.9
26.0
21.2
18.6
16.1
10.0
9.2
8.0

48
68
80
89
89
89
91
94
96
109
110
105

1 Excluding 496 infants who died not fed.
2 Per cent not shown for “ not reported” group because not significant.
3 Excluding 49 infants who died not fed.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

10.0
15.5
19.0
22.1
22.9
23.6
24.4
25.7
27.6
32.1
32.5
31.1

126
154
180
191
187
190
203
204
196
197
197
206

26.3
35.2
42.9
47.4
48.2
50.4
54.4
55.7
56.3
57.9
58.3
60.-4,

209

A P P E N D IX D .-----G E N E R A L T A B L E S
G

eneral

able

5 9 .—

Weaning o f twins in pairs, by age when first twin was
weaned; twins in six c itie s 1
Pairs of twins both of whom were
living when the first was w ea n ed 8

Age when first tw in was weaned
Total

Both
weaned
at the
same
time

One
weaned,
one
partly
breast
fed

T otal________________________

Under 1 m on th . _________
1 month, under 2________ _____
2 months, under 3____________
3 months, under 4______________
5 months, under 6________
6 months, under 7______________
7 months, under 8_______ _____
9 months, under 10_______ .
11 months, under 12...........................

29
10
4

3
2
1
1
3

One
weaned,
one
breast
fed

1 Omitting Johnstown and Baltimore.

1At the end of the first year 22 pairs of .twins survived of whom neither had been weaned.
G

eneral

a b l e 6 0 . — Proportion o f births to mothers under 20 and to those SB and
over, by single and plural births; live births in eight cities

Live births—

To mothers under
20, and 35 and over

Single and plural births
Total

Number
Total__________________________
Single......................... ................
Plural__________ _____ _______ _

eneral

able

Per cent

22,967

5,230

22.8

22,438
529

5,110
120

22.8
22.7

6 1 .—

Proportion o f births fifth and later in order, by single and
plural births; live births in eight cities
Live births—

Single and plural births

Total

Fifth and later in
order
Number

Total_________ __________________ ____
Single_________________ ____ ___
P lural................................................... ......

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

22,967
22,438
529

Per cent

5,974

26.0

5,794
180

25.8
34.0

210
G

CA U SAL. F A C T O R S I N

I N F A N T M O R T A L IT Y

T a b l e 6 2 . — Relative mortality among plural and single births, when
influence o f age o f mother, order o f birth, and both factors is eliminated; live births
in eight cities

eneral

Infant deaths: Twins and triplets
Expected at average rates for single births—
Order of birth; age of
mother
Actual

Expected at
average rate for
all single births

Of same order
of birth

T o mothers of
same age

Of same order
of birth and to
mothers of same
age

Number Ratio Number Ratio Number Ratio Number
T otal_________

55.7

3.45

57.0

3.37

9.6
9.0
9.5
6.1
5.5
5.8
3.2
1.7
1.1
5.5

3.54
3.67
2.42
3.61
4.00
3.97
1.56
4.12
4.55
3.27

55.2

Ratio

55.7

3.45

9.1
8.7
9.3
6.3
5.3
5.9
3.3
1.6
1.0
5.2

3.74
3.79
2.47
3.49
4.15
3.90
1.52
4.38
5.00
3.46

1.8

5.03
4.03
3.41
3.38
2.63
3.09

OEDEE OF BEETH

First.............................
Second.........................
T h i r d . ..................... .
Fourth.......................
F ifth........ ...................
Sixth.......................... .
Seventh_________ . . .
E ighth_____________
N in th ........ .................
Tenth and la te r.____
AGE OF MOTHEB

Under 20 years______

1.7
12.8
15.4
12.2
9.9
3.2

20-24..........................
25-29................... .I
30-34..........................
35-39..................... .
40 years and over___

5.29
4.22
3.38
3.28
2.63
3.44

13.4
15.3
11.8
9.9
3.6

T a b l e 6 3 . — Proportion o f births to mothers o f nationalities 1 with high
infant mortality rates, by single and plural births; live births in eight cities

eneral

Live births—

Single and plural births
Total

T o mothers of na
tionalities with
high infant mor
tality rates i
Number

Total.........................................................................................
Single..............................................................................
Plural_____________________ ___________________

22,967

7,428

32.3

22,438
529

7,272
156

32.4
29.5

1Including French-Canadian, Polish, Portuguese, “ other foreign born,” and colored.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Per cent

211

APPENDIX D . — GENERAL TABLES
G

eneral

T a b l e 64. — Proportion of births in fam ilies in which father earned less
than $650, by single and plural births; live births in eight cities

Live births—

Single and plural births
Total

In families in which
father earned less
than $650
N um ber

T o t a l........................ .......................................................
Single................................................................................. . .....................
P lural......... ........................ .......................................

Per cent

21,536

9,133

42.4

21,054
482

8,913
220

42.3
45.6

T a b l e 6 6 .— Prevalence o f plural births among births preceded by plural
births; all pregnancies reported by mothers o f infants in eight cities

eneral

Pregnancies not preceded by
plural births—

Pregnancies preceded by
plural births—

Resulting in plural
births

Order of pregnancy
Total

Resulting in plural
births
Total
Actual Expected
number1 number 3

Number Per 1,000
T o t a l...._____________ ___________

74,485

725

9.7

1,507

First..................................................
Second........................ ...................... ..........
Third_____________ _____
Fourth__________ _________ _
Fifth_______ ____________
Sixth________________________
Seventh___________________
Eighth_______ ____ _____
Ninth________________________
Tenth and later_______ ______ ______ _

22,061
15,900
11,127
7,956
5,589
3'934
2)756
l) 888
1,273
2)001

179
118
120
94
‘ 65
48
29
21
13
38

8.1
7.4
10.8
11. 8
11. 6
12. 2
10. 5
11.1
10. 2
19.0

130
161
189
204
182
160
130
109
242

18.4
1.0
17
2J2
2lA
¿_2
1.7
1. 4

'Ll
4 .6

1 Details as to distribution b y order of pregnancy not available.
3 Expected at the rate shown in colum n 3.
G

T a b l e 6 6 .— Proportion o f confinements in fam ilies in which father
earned less than $650, by type o f delivery; confinements in Baltimore

eneral

Confinements—

T y p e o f delivery
T otal

In families in which
father earned less
than $650
N um ber

T otal___________________ ________________________________________
Instrumental____ ___________________________
Other...................................................................................................

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Per cent

11,463

5,017

43.8

866
10,597

258
4,759

29.8
44.9

eneral

able

212

6 7 .— Monthly death rates, by cause o f death, type o f feeding, and month o f life; infants in eight cities
Infants surviving at beginning of specified month
Infant deaths from specified causes

Total

All causes

Gastric and in
testinal diseases

Respiratory
diseases

Malformations

Epidemic and
Early infancy other communi
cable diseases

Diseases ill
defined and
unknown

Other causes

Per 1,000 Num Per 1,000
Num Per 1,000 Num Per 1,000 Num Per 1,000 Num Per 1,000 Num Per 1,000 Num Per 1,000 Num survivors
ber survivors
ber survivors1 ber survivors1 ber survivors ber survivors ber survivors1 ber survivors ber
First month.

22,967

1,028

44.8

3.0

66,

2.9

3.3

30.3

1 .0

1 .1

3 .0

■ 8

4
4

1.7
7.3

1
17

2 .2
1 .5
3 .1

31.2

42
1
7
20

36.7

4
4

.2
.2

22
11
2
9

. 1.0
.6
1.5
2.6

11
3
1
7

.5
.2
.6
1.6

14
3
2
9

.6
2
1.7

25
9
3
13

1.2
.7
.9
2.2

17
2
10
47

.9
2.9
4.4
86.2

155
16
72
450
4

2.1
1.9
3.9
2.3

3
2

.1
.1

.8
.8

2.3
.9
3! 9
8.4

17
13

50
16
5
29

1.2

38
20
6
12

1.7
1.3
3.4
2.7

6
1

.3
.1

13
8
1
4

.6
.5
.6
.9

.4
.3

1.1

.8
.2
1.1
2.7

9
4

17
3
2
12

1,1

3.5
.7
4.1
10.2

46
21
6
19

2.1
1.6
2.2
3.5

5
2

.2
.1

12
6
2
4

.6
‘ .4
.7
.7

.1
.1

.8
.2
1.1
2.2

3
2

18
3
3
12

3.7
.8
3.3
9.8

33
14
4
15

1.5
1.1
1.2
2.6

13
1

.6
.1

11
6

.5
.5

2.1

1
2

.3
.3

2.6

19,438
686
2,287
645
11

329
25
125
545
4

16.9
36.4
54.7
1,000.0

41
6
19
3

2.1
8.7
8.3
5.5

50
12
4

5.2
7.3

Second m o n th ....______ ______
Breast____________________
Partly breast........................ .
A r tificia l....._________ —
Not reported___________—

21,939
17,178
1,294
3,457
10

204
100
19
85

9.3
5.8
14.7
24.6

63
22
7
34

2.9
1.3
6.4
9.8

45
32
5
8

Third month____
Breast............
Partly breast.
Artificial____
Not reported.

21,735
15,509
1,786
4,431
9

175
58
23
94

8.1
3.7
12.9
21.2

81
19
13
49

3.7
1.2
7.3
11.1

Fourth month___
Breast...;___
Partly breast.
Artificial____
Not reported.

21,560
13,516
2,668
5,366

173
46
24
103

8.0
3.4
9.0
19.2

75
9
11
55

Fifth month____
Breast______
Partly breast.
Artificial____
Not reported.
FRASER

21,387
12,263
3,317
5,797
10

165
40
19
105
1

7.7
3.3
5.7
18.1

79
10
11
57
1

1
1

(2)
.2

I N F A N T M O R T A L IT Y

697

8.0
23.3
31.5
825.7

Breast____________________
Partly breast______________
Artificial__________________
Not fed, died at o n ce ...........
Not reported______________

Digitized for
https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

C A U SAL FACTO RS IN

Type of feeding and month of life

Sixth m onthiii___..

96515°—25t

21,222

156

7.4

3.8

1.6

10,969
4,098
6,145
10

23
24
109

2.1
5.9
17.7

7
12
62

.6
2.9
10.1

9
5
19

.8
1..2
3.1

2
2
10

.2
.5
1.6

2
1
4

.2
.2
.7

Seventh m onth_______________

21,066

132

6.3

3.4

1.6

Breast................................ .
Partly breast..........................
Artificial__________________
Not reported.... .....................

8,641
5,801
6,615
9

16
23
93

1.9
4.0
14.1

3
9
59

.3
1.6
8.9

7
11
15

.8
1.9
2.3

Eighth m onth............ ........... .

20,934

122

5.8

2.4

2.0

Breast.....................................
Partly breast..........................
Artificial__________________
Not reported—......................

7,343
6,671
6,911
9

21
22
78
1

2.9
3.3
11.3

4
10
36
1

.5
1.5
5.2

11
8
22

1.5
1.2
3.2

Ninth m onth_________________

20,812

119

5.7

2.3

1.7

Breast____________________
Partly breast______________
Artificial__________________
Not reported______________

5,853
7,684
7,268
7

19
22
78

3.2
2.9
10.7

5
7
36

.9
.9
5.0

7
8
21

1.2
1.0
2.9

Tenth m onth_________

.2
1. Q
1.5

.6
.-6

5
3
4

3
2
10

.4
.3
1.4

4
3
10

.7
.4
1.4

5
1
7

1.2
.1
.9

.5
.3
.4
.6
.8

.1
(*)

109

5.3

2.6

1.4

16
20
73

3.8
2.3
9.3

3
10
40

.7
1.2
5.1

6
6
17

1.4
.7
2.2

Eleventh m onth........................ .

20,584

3.9

1.7

25 ,

1.2

Breast_________ ___________
Partly breast______________
Artificial__________________
Not reported______________

3,278
9,062
8,235
9

8
23
49

2.4
2.5
6.0

4
8
24

1.2
.9
2.9

2
9
14

.6
1.0
1.7

1
4
5

Twelfth m onth_______________

20,504

4.5

1.8

1.2

12
25
55

4.4
2.7
6.4

3
9
24

1.1
1.0
2.8

7
7
11

2.6
.8
1.3

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

2
4
9

(*)

4,248
8,591
7,845
9

1 Not shown where base is less than 100.
1 Less than one-tenth of 1 per cent.

20,693

2,736
9,145
8', 616
7

1.1

Breast - - Partly breast...................... .
Artificial _________________
Not reported..........................

Breast____________________
Partly breast______________
Artificial__________________
Not reported-.......................

(*)

1
1

1
3

.1
(’)

.1
.3

6
10

.7
1. 2

3
1
4

1
1

.1
,i

2
3
7

-3
f4
'll o

1
3
5

.3
.6

1
1

.1
.1

1
1
4

.3
T;1
.5

.1
.1

2
1
6

.7
.1
.7

1
1

APBENM X I>.— GENERAL TABLES

r__ . . __

Breast.....................................
Partly breast.........................
Artificial-........................... .
Not reported______________

to
¡7 -1

214

CAUSAL FACTORS IN

IN F A N T M O R T A L IT Y

G e n e r a l T a b l e 6 8 . — Monthly death rates o f infants artificially fed, by month o f

life in which artificial feeding began; infants artificially fed in eight cities
Infants artificially fed
Months of life in which artificial feeding began
Deaths during
month
Survivors at
begin
ning’
of
Per
month Num
1,000
ber survivors

Month of life

First.................; ...........
Second______________
Third............................
Fourth..........................
Fifth............................
Sixth..____ __________
Seventh......................
Eighth____ __________
Ninth......... ..................
Tenth____... ............
Eleventh____________
Twelfth........................

2,266
3,435
4,419
5,359
5, 789
6,139
6,609
6,907
7,262
7,842
8,233
8,168

125
85
94
103
105
109
93
78
78
73
50
54

55.2
24.7
21.3
19.2
18.1
17.8
14.1
11.3
10.7
9.3
6.1
6.3

First

Second

Deaths during
Deaths during
Surviv
Surviv
month
month
ors at
ors at
begin
begin
ning
ning
Per
Per
Num 1,000
of
of
Num 1,000
month
ber survivors month
ber survivors
2,266
2,141
2,069
2,015
1,955
1,908
1,872
1,835
1,817
1,791
1,766
1,754

125
72
54
60
47
36
37
18
26
25
12
23

55. 2
33.6
26. 1
29.8
24.0
18.9
19.8'
9.8
14.3
14.0
6.8
13.1

1,294
1,281
1,254
1,229
1,206
1,184
1,161
1,140
1,122
1,115
1,103

13
27
25
23
22
23
21
18
7
12
5

10.0
21.1
19.9
18.7
18.2
19.4
18.1
15.8
6.2
10.8
4.5

Infants artificially fed—Continued
Months of life in which artificial feeding began—Continued
Third

Month of life

Fourth

Deaths during
month

Fifth

Deaths during
month

Surviv
Surviv
Surviv Deaths during
month
ors at
ors at
ors at
begin
begin
begin
ning
Per
ning
Per
ning
Per
Num 1,000
Num 1,000
Num 1,000
of
of
of
ber survivors
ber survivors month
ber
month
month
survivors
Third..................... ......
Fourth..........................
Fifth.............................
Sixth____________ _
Seventh___________
Eighth______________
N in th ...____ ________
Tenth_______________
Eleventh____________
Twelfth........................

1,069
1,056
1,039
1,020
998
990
977
964
955
948

13
17
19
22
8
13
13
9
7

12.2
16.1
18.3
21.6
8.0
13.1
13.3
9.3
7.3

6.3

1,034
1,033
1,019
997
985
971
960
950
947

1
14
22
12
14
11
10
3

1. 0
13.6
21.6
12.0
14.2
11.3
10.4
3.2
2.1

533
531
526
520
516
513
507
504

2
5
6
4
3
6
3

3.8
9.4
11.4
7.7
5.8
11.7
5.9

9.9

Infants artificially fed—Continued
Months of life in which artificial feeding began—Continued
Month
of life

Sixth..........
Seventh___
Eighth.......
Ninth____
Tenth____
Eleventh...
Twelfth___

Sixth

Seventh

Eighth

Deaths durDeaths durSurviv- ing month Surviv ing month
ors at
ors at
beginbeginPer
ning Num- Per
ning Num- 1,000
1,000
month ber surviv- month ber survivors
ors
455
453
448
446
441
436
433

2
5
2
5
5
3
5

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

4.4
11.0
4.5
11. 2
11.3
6.9
11.5

579
577
572
571
564
562

2
5
1
7
2

3.5
8.7
1.7
12.3
3.5

Ninth and later

Deaths durSurviv- ing month Surviv- ine month
ors at
ors at
beginbeginPer
ning Num- 1,000
ning Num1,000
ber survivmonth ber survivors
ors

391
390
389
387
385

1
1
2
2

2.6
2.6
5.1
5.2

433
1,091
1,553
1,982

2
6
8

1.8
3.9
4,0

215

A P P E N D IX D .-----G E N E R A L T A B L E S
G

T a b l e 6 9 . — Monthly mortality o f infants artificially fed, by month o f life
in which artificial feeding began; single full-term live births in eight cities to mothers
who survived first year o f infant’ s life

eneral

Infants artificially fed
Months of life in which artificial feeding began

Month of life

Sur
First
vivors Deaths
at
during
begin
Sur
ning of month vivors
Deaths
month
at
dining
begin month
ning of
month
1,926
3,051
3,966
4,874
6,294
5,632
6,081
6,380
6,737
7,304
7,691
8,056

Fourth____________
Fifth...................... .

N in th ...._________
Twelfth.......... ..........

62
62
71
86
90
97
77
55
66
64
49
46

62
51
33
50
37
31
26
16
20
20
10
18

1,926
1,864
1,813
li 780
1,730
1,693
1,662
1,636
1,620
1,600
1,580
1,570

Second

Fourth

Third

Sur
Sur
Sur
vivors Deaths vivors Deaths vivors Deaths
at
at
at
during
begin during begin during begin month
ning of month ning of month ning of
month
month
month

1,187
1,176
1,151
1,131
1,108
1,088
1,067
1,055
1,041
1,036
1,024

11
25
20
23
20
21
12
14
5
12
4

977
964
949
932
912
904
897
885
876
869

13
15
17
20
8
7
12
9
7
6

979
978
966
947
937
927
916
906
903

1
12
19
10
10
11
10
3
2

Infants artificially fed—Continued
Months of life in which artificial feeding began —Continued

eneral

506
505
500
494
491
488
483
479
T

Eighth

Ninth and later

Sur
Sur
Sur
Sur
Sur
vivors Deaths vivors Deaths vivors Deaths vivors Deaths vivors Deaths
at
at
at
at
at
during begin during begin during begin during begin during
begin month
month ning of month
ning of month ning of month ning of
ning of
month
month
month
month
month

Fifth

Seventh

Sixth

Fifth
Month of life

able

5
6
3
3
5
4
3

428
426
422
420
415
411
408

2
4
2
5
4
3
5

546
544
540
540
533
531

2
4
7
2

, 376
375
374
372
370

1
1
2
2

412
1,045
1,494
1,902

2
6
8

7 0 . — Monthly death rates, by month o f life and color and
nationality o f mother; infants in eight cities

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

216

CAU SAL FACTORS IN

I N F A N T M O R T A L IT Y

G e n e r a l T a b l e 71 .— Type o f feeding, by color and nationality o f mother; months

lived from birth to end o f ninth by infants in eight cities

Months lived from birth to end of ninth

Color and nationality
ef mother

Months of exclu
sively breast
feeding

Total

Number

Months of partly
breast feeding

Months of artifi
cial feeding

Type of
feeding
not re
ported
(num
ber) 1

Per cent Number Percent Number Per cent Months

Total_______ 192,212.5

110,384.0

57.4

33,904.5

17.6

47,842.0

24.9

82.0

White________ _______ 180,397. 5

103,909.0

57.6

30,890.0

17.1

45,516. 6

25.2

82.0

■ Native............ ........ 102,285. 5
Foreign born.......... 78,112.0
Italian________ 11,943.0
Jewish............. 10,688.0
French-Canadian________
8,666.0
German............
6,514.0
Polish________
10,391.5
5,410. 5
Portuguese.......
Other________
24,471.0
Not reported—
18.0

57,514.5
46,394. 5
8,193.0
6,570. 5

56.2
59.4
68.6
61.5

15,785. 5
15,104. 5
2,187.0
2,894. 5

15.4
19.3
18.3
27.1

28,962.0
16,554. 5
1,563.0
1,207.0

28.3
21.1
13.1
11.3

23.5
58.5

3,704.0
3; 683.0
6,850. 5
2,639. 5
14,749.0
5.0

42.7
56.5
65.9
48.8
60.3
27.8

1.148.5
1.433.5
2,363.0
1,045.0
4,027.0
6.0

13.3
22.0
22.7
19.3
16.5
33.3

3,813. 5
1,405.5
1,155. 5
1,725. 5
5,677. 5
7.0

44.0
21.5
11.1
31.9
23.2
38.9

6,475.0

54.8

3,014.5

25.5

2,325.5

19.7

Colored______________

11,815.0

16.0
2.0
22.5
18.0

1Per cent not shown for “ not reported” group because not significant.
G e n e r a l T a b l e 72. — Prevalence o f breast and artificial feeding, by month of

infant’ s life and color and nationality o f mother; infants in eight cities
Infants surviving at beginning of each specified month
Month of infant’s life and color
and nationality of mother

Breast fed during
month

Partly breast fed
during month

Artificially fed
during month

Total 1
Number

Per cent Number Per cent Number Per cent

White:
First......................................
Second___________________
Third____ _______________
Fourth___________________
Fifth____________________
Sixth____________________
Seventh__________________
Eighth___________________
Ninth___________________
Tenth____________ _______
Eleventh_________________
Twelfth...... ..........................

21,008
20,576
20,387
20,223
20,072
19,923
19,783
19,662
19,549
19,437
19,337
19,264

18,162
16,106
14,567
12,722
11,557
10,348
8,194
6,976
5,570
4,064
3,148
2,634

86.5
78.3
71.5
62.9
57.6
51.9
41.4
35.5
28.5
20.9
16.3
13.7

646
1,162
1,586
2,385
2,986
3,717
5,298
6,122
7,078
7,930
8,373
8,446

3.1
5.6
7.8
11.8
14.9
18.7
26.8
31.1
36.2
40.8
43.3
43.8

2,189
3,298
4,225
5,106
5,519
5,848
6,282
6,555
6,894
7,434
7,807
8,177

10.4
16.0
20.7
25.2
27.5
29.4
31.8
33.3
35.3
38.2
40.4
42.4

Native—
First...............................
Second...................... —
Third................ ............
Fourth______ _________
Fifth............ ......... . . . . .
Sixth_______________ .
Seventh.............. ...........
Eighth______ _________
Ninth........................ —
Tenth.............................
Eleventh.................... .
Twelfth..........................

11,815
11,600
11,518
11,451
11,377
11,310
11,246
11,192
11,141
11,086
11,044
11,011

10,107
8,856
7,995
6,951
6,335
5,737
4,585
3,924
3,145
2,227
1,638
1,304

85.5
76.3
69.4
60.7
55.7
50.7
40.8
35.1
28.2
20.1
14.8
11.8

314
589
758
1,179
1,491
1,851
2,699
3,182
3,756
4,318
4,670
4,787

2.7
5.1
6.6
10.3
13.1
16.4
24.0
28.4
33.7
39.0
42.3
43.5

1,389
2,152
2,763
3,318
3,548
3,719
3,960
4,084
4,238
4,538
4,733
4,918

11.8
18.6
24.0
29.0
31.2
32.9
35.2
36.5
38.0
40.9
42TS
44.7

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

217

A P P E N D IX D .— G E N E R A L T A B L E S

G e n e r a l T a b l e 72 .— Prevalence o f breast and artificial feeding, by month of

infant’ s life and color and nationality o f mother; infants in eight cities — Con.
Infants surviving at beginning of each specified month
Breast fed during
month

of infant’ s life and color
nationality of mother

Partly breast fed
during month

Artificially fed
during month

Total
Number
—Continued,
reign bom—
First...............................
Second......... .................
T hird.............................
Fourth...........................
Fifth_________________
Sixth________ _____
Seventh.------- -----------Eighth_____ __________
Ninth.............................
T e n th ......................... Eleventh......................
Twelfth.............. ........

Per cent Number Per cent Number Per cent

9,193
8,976
8,869
8,772
8,695 *
8,613
8,537
8,470
8,408
8,351
8,293
8,253
'

8,055
7,250
6,572
5,771
5,222
4,611
3,609
3,052
2,425
1,837
1,510
1,330

87.6
80.8
74.1
65.8
60.1
53.5
42.3
36.0
28.8
22.0
18.2
16.1

332
573
828
1,206
1,495
1,866
2,599
2,940
3,322
3,612
3,703
3,659

3.6
6.4
9.3
13.7
17.2
21.7
30.4
34.7
39.5
43.3
44.7
44.3

Italian—
F ir s t......................
Second.....................
Third.... ........... ......
Fourth................... .
Fifth........................
Sixth....... ................
Seventh..............
E ig h th ...................
Ninth......................
T en th .....................
Eleventh.................
Twelfth.................

1,390
1,360
1,348
1,333
1,326
1,319
1,311
1,305
1,299
1,294
1,289
1,282

1,284
1,206
1,133
1,042
964
854
700
574
466
368
299
275

92.4
88.7
84.1
78.2
72.7
64.7
53.4
44.0
35.9
28.4
23.2
21.5

46
66
103
145
192
262
382
461
536
690
620
617

3.3
4.9
7.6
10.9
14.5
19.9
29.1
35.3
41.3
45.6
48.1
48.1

60
88
112
146
170
203
229
270
297
336370
390

4.3
6.5
8.3
11.0
12.8
15.4
17.5
20.7
22.9
26.0
28.7
30.4

Jewish—
First........................
Second.....................
Third.......................
Fourth.....................
Fifth............ ...........
Sixth........................
Seventh...................
Eighth.................
Ninth____________
Tenth................. .
Eleventh.................
Twelfth...................

1,213
1,198
1,194
1,190
1,187
1,183
1,182
1,182
1,178
1,175
1,171
1,169

1,130
1,039
966
831
758
671
492
402
292
216
172
137

93.2
86.7
80.9
69.8
63.9
56.7
41.6
34.0
24.8
18.4
14.7
11.7

45
91
139
232
284
356
509
579
662
704
708
714

3.7
7.6
11.6
19.5
23.9
30.1
43.1
49.0
56.2
59.9
60.5
61.1

37
67
88
125
143
153
178
198
223
254
290
318

3.1
5.6
7.4
10.5
12.0
12.9
15.1
16.8
18.9
21.6
24.8
27.2

French-Canadian—
First........................
Second.....................
Third................... .
Fourth.....................
Fifth........................
Sixth......... ...............
Seventh............ ......
Eighth......... ...........
Ninth......................
Tenth......................
Eleventh................
Twelfth................ —

1,040
1,016
996
980
967
951
941
924
918
906
899
896

805
681
557
440
370
305
231
191
141
110
84
75

77.4
67.0
55.9
44.9
38.3
32. 1
24.5
20.7
15.4
12.1
9.3
8.4

37
56
86
118
132
158
181
186
202
195
184
168

3.6
5.5
8.6
12.0
13.7
16.6
19.2
20. 1
22.0
21.5
20.5
18.8

198
279
353
422
465
488
529
547
575
600
630
652

19.0
27.5
35.4
43.1
48.1
51.3
56.2
59.2
62.6
66.2
70.1
72.8

German—
First........................
Second................
Third.......................
Fourth................... .
F ifth ..___________
Sixth______ ______
Seventh...................
Eighth.............. ......
Ninth.............. ........
Tenth......................
Eleventh_________
Twelfth...................

762
743
736
728
725
722
715
713
708
706
701
700

646
569
509
452
406
363
296
255
198
131
95
74

84.8
76.6
69.2
62.1
56.0
50.3
■ 41.4
35.8
28.0
18.6
13.6
10.6

38
70
88
114
147
177
234
263
305
339
349
345

5.0
9.4
12.0
15.7
20.3
24.5
32.7
36.9
43.1
48.0
49.8
49.3

77
103
139
162
172
182
185
195
205
236
257
281

10.1
13.9
18.9
22.3
23.7
25.2
25.9
27.3
29.0
33.4
36.7
40.1

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

800
1,146
1,462
1,788
1,971
2,129
2,322
2,471
2,656
2,896
3,074
3,259

8.7
12.8
16.5
20.4
22.7
24.7
27.2
29.2
31.6
34.7
37.1
39.5

218

CAUSAL FACTORS IN IN F A N T MORTALITY

G e n e r a l T a b l e 7 2 .— Prevalence o f breast and artificial feeding, by month of

infant’s life and color and nationality o f mother; infants in eight cities — Con.
Infants surviving at beginning of each specified month
Month of infant’s life and color
and nationality of mother

Breast fed during
month

Partly breast fed
during month

Artificially fed
during month

Total
Number Per cent Number Per cent Number Per cent
White—Continued.
Foreign born—Continued.
Polish—•
F irst.. __________
Second___________
Third____________
Fourth___________
Fifth____ _________
Sixth_____________
S eventh.................
Eighth____ _______
Ninth____________
Tenth____________
Eleventh.................
Twelfth...................

1,238
1,200
1,188
1,168
1,159
1,145
1,133
1,123
1,107
1,099
1,088
1,075

1,137
1,041
979
884
807
712
534
• 447
343
273
225
188

91.8
86.8
82.4
75.7.
69.6
62.2
47.1
39.8
31.0
24.8
20.7
17.5

41
79
107
167
222
281
430
494
557
592
614
610

3.3
6.6
9.0
14.3
19.2
24.5
38.0
44.0
50.3
53.9
56.4
56.7

58
77
98
114
127
150
167
180
205
232
247
275

4.7
6.4
8.2
9.8
11.0
13.1
14.7
16.0
18.5
21.1
22.7
25.6

Portuguese—
First________
Second___________
Third____ _____
Fourth___________
Fifth_____________
Sixth__________
Seventh__________
Eighth__________
Ninth......... . . . .
Tenth____________
Eleventh..._______
Twelfth__________

657
642
631
621
604
596
585
568
559
551
542
538

530
455
376
292
257
234
187
172
148
125
122
114

80.7
70.9
59.6
47.0
42.5
39.3
32.0
30.3
26.5
22.7
22.5
21.2

51
73
100
125
129
134
148
145
150
160
156
148

7.8
11.4
15.8
20.1
21.4
22.5
25.3
25.5
26.8
29.0
28.8
27.5

76
114
155
204
218
228
250
251
261
266
264
276

11.6
17.8
24.6
32.9
36.1
38.3
42.7
44.2
46.7
48.3
48.7
51.3

Other—
First...... ..................
Second................. .
Third_______ : . . .
Fourth___________
Fifth_____________
Sixth_____________
Seventh__________
Eighth_________
Ninth_____ _______
Tenth____________
Eleventh_______
Twelfth_______ _

2,891
2,815
2,774
2,750
2,725
2,695
2,668
2,653
2,637
2,618
2,601
2,591

2,521
2,257
2,051
1,830
1,660
1,472
1,169
1,011
837
614
513
467

87.2
80.2
73.9
66.5
60.9
54.6
43.8
38.1
31.7
23.5
19.7
18.0

74
138
205
304
388
497
714
811
909
1,031
1,071
1,056

2.6
4.9
7.4
11.1
14.2
18.4
26.8
30.6
34.5
39.4
41.2
40.8

294
418
516
614
675
724
783
829
889
971
1,015
^ 1,066

10.2
14.8
18.6
22.3
24.8
26.9
29.3
3L2
33.7
37.1
39.0
4L 1

Nationality not reported—
First.........................
Second___________
Third...... ................
Fourth___________
Fifth_____________
Sixth_____________
Seventh__________
Eighth___________
Ninth____________
Tenth____________
Eleventh_________
T w elfth..________

2
2
2
2
•2
2
2
2
2
2
2
2

2
2
1

Colored:
First...... ...............................
Second___________________
Third_______ _____ _______
Fourth___________________
F ift h ...._______________
Sixth____________________
Seventh__________________
Eighth___________________
Ninth___________________
Tenth___________________
Eleventh___. ____________
T w elfth.._______________

1,414
1,363
1,348
1,337
1,315
1,299
1,283
1,272
1,263
1,256
1,247
1,240

1,276
1,072
942
794
706
621
447
367
283
184
130
102

i Excluding those who died not fed.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

1
1
1
1
1
1
1
1
1
1

1
1
1
1
1
1
1
1
1
90.2
78.7
69.9
59.4
53.7
47.8
34.8
28.9
22.4
14.6
10.4
8.2

40
132
200
283
331
381
503
549
606
661
689
699

2.8
9.7
14.8
21.2
25.2
29.3
39.2
43.2
48.0
52.6
55.3
56.4

98
159
206
260
278
297
333«
356
374
411
428
439

6.9
11.7
15.3
19.4
21.1
22.9
26.0
28.fi29.6
32.7
34.3
35.4

A P P E N D IX

219

D . ------G E N E R A L . T A B L E S

73.— M o n t h l y death rates, hy color an d n a tio n a lity o f m other and
b y m onth o f life an d t y p e o f fe e d i n g ; in fa n ts i n eight cities

G en eral T able

Monthly death rates1
Color and nationality of mother
Type of feeding and
month of life

White
Total

Foreign born
Total Na
tive

First...........................
Breast__________
Partly breast____
Artificial_______
Second........................
Breast__________
Partly breast.......
Artificial______• _
Third.............
Breast__________
Partly breast____
Artificial..............
Fourth......
Breast. ................
Partly breast____
Artificial_______
Fifth...........................
Breast. ................
Partly breast.......
Artificial_______
Sixth_______ _______
B reast......... ......
Partly breast.......
Artificial_______
Seventh____ _______
Breast .......... .
Partly breast.......
Artificial_______
Eighth...__________
Breast__________
Partly breast.......
Artificial......... .
Ninth.........................
Breasts_________
Artificial_______
Tenth.........................
Breast__________
Partly breast
Artificial.............
Eleventh..................
Partly breast___
Artificial_______
Twelfth................. .
B reast......... ......
Partly breast___
Artificial..............

Ger
Jew FrenchTotal Ital
ana man
ian
ish Cdian

44.8 43.4 41.5 45.9
16.9 16.2 14.0 19.0
36.4 34.1 44.6 24.1
54.7 50.7 40.3 68.8
9.2
9.3
7.1 11.9
5.8
3.6
8.3
5.7
14.7 15.5 11.9 19.2
24.6 24.0 20.0 31.4
5.8 10.9
8.1
8.0
1.8
3.7
3.7
6.1
12.9 13.2
7.9 18.1
21.2 21.1 17.0 28.7
7.5
6.5
8.8
8.0
3.4
1.9
4.2
2.9
8.4
2.5 14.1
9.0
19.2 18.4 17.5 20.1
5.9
9.4
7.7
7.4
2.5
3.3
3.2
4.0
5.7
5.4
2.7
8.0
18.1 17.2 13.2 24.4
7.4
5.7
8.8
7.0
1.6
2.4
2.1
1.9
3.2
5.9
8.6
5.9
17.7 16.8 13.2 23.1
6. 3 6.1
4.8
7.8
1.9
1.1
2.2
1.6
2.2
5.4
4.0
3.8
14.1 14.0 10.9 19.4
5.8
4.6
7.3
5.7
4.9
2.9
2.9
1.3
3.3
3.3
2.5
4.0
11.3 11.0
9.3 13.8
4.9
6.8
5.7
5.7
3.2
5.4
3.2
1.6
2.4
2.9
3.5
3.0
10.7 10.6
8.7 13.6
5.3
3.8
6.9
5.1
4.9
3.8
3.9
3.1
2.3
2.1
1.6
2.8
6.2 13.5
9.3
9.0
3.9
4.8
3.8
3.0
2.4
2.2
.6
4.0
1.5
3.8
2.5
2.5
6.0
5.8
5.3
6.5
4.4
4.8
4.5
4.0
4.4
3.8
6.0
1.5
2.1
2.7
2.6
3.3
6.4
6.4
6.5
&1

1Not shown where base is less than 100.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

46.3
19.5
21.7
66.7
8.8
8.3
22.7
11.1
7.1
19.4
44.6
5.3
1.9
13.8
20.5
5.3
5.2
10.4
6.1
2.3
11.5
14.8
4.6
5.7
2.6
4.4
4.6
3.5
2.2
11.1
3.8
4.3
10.1
3.9
5.4
3.4
3.0
5.4
3.3
3.2
10.8
3.1
7.3
1.6
2.6

28.4
9.7
81. i
3.3
2.9
11.0
3.4
2.1
22.7
2.5
1.2
4.3
8.0
3.4
1.3
7.0
7.0
.8
6.5

3.4
2.5
16. i
2.5
6.8
1.5
3.4
15.7
1.7
1.4
3.4
1.7
7.3
3.1

54.0 42.5
13.7 20.1
54.1
55.6 77.9
19.7
9.4
13.2 10.5
17.9 14.3
35.8
16.1 10.9
10.8
23.3 34.1
22.7 36.0
4.1
13.3
9.1
2.2
16.9
17.0 12.3
4.1
16.5
2.5
2.7
15.2
28.0 lì. 6
10.5
9.7
3.3
12.7
5.6
14.3 32.9
18.1
2.8
4.3
11.0
26.5 15.8
6.5
7.0
5.2
5.4
7.3 25.6
13.1
2.8
5.1
5.0
19.1
4.9
7.7
7.1
7.6
10.3
2.9
8.3 12.7
3.3
1.4
4.8
6.7
26.7
11.9
3.1

2.9
5.7
2.9
10.7

Col
ored
Pol
ish

Portu
guese

Other

52.1
25.5
24.4
137.9
10.0
8.7

40.4
13.2
19.6
92.1
17.1
8.9
54.5
26.3
15.8
8.0

49.6
22.6
40.5
54.4
14.6
8.4
29.0
43.1
8.7
5.4
14. 6
19.4
9.1
3.8
13. 2
22.8
11.0
3.6
2.6
34.1
10.0
4.1
8.0
23.5
5.6
.9
2.8
15.3
6.0
5.9
3.7
8.4
7.2
6.0
2.5
13.5
6.5
4.9
1.9
12.4
3.8
7.8
2.8
3.0
5.0
2.1
4.7
6.6

39.6
16.8
10.2
46.7
51.0
7.7
5.7
17.9
8.8
12.1
7.4
22.5
15.7
10.5
1.4
10.7
53.3
8.8
1.9
9.3
30.0
14.2
8.9
12.1
33.3
7.2
5.8
5.4
14.6
10.0
7. 3
3.4
30.2
11.9
4.4
8.1
28.3
7.4
5.3
3.3
18.2

45.2
27.4
13.7
40.0
39.2
13.2
3.9
32.1
18.5
4.3
22.4
30.7
29.1
5.3
33.8
44.0
15.8
5.8
6.9
27.9
14.3
6.8
6.7
23.0
16.3
8.0
6.3
26.3
7.4
12.8
7.6
5.6
8.8
6.8
3.6

64.5
26.6
75.0
42.9
11.0
7.5
7.6
37.7
8.2
4.2
10.0
24.3
16.5
11.3
14.1
34.6
12.2
4.2
9.1
36.0
12.3
4.8
5.2
37.0
8. 6
6. 7
6.0
15.0
7.1
2.7
3.6
16.9
5.5
3.5
1.7
13.4
7.2
4.5
14.6
5.6
7.7
2.9
9.3
6.5
19.6
4.3
6.8

2 2 0

CAU SAL

FACTORS

IN F A N T

M O R T A L IT Y

74.— R elative m orta lity, b y n a tio n a lity o f m other, f o r in fa n ts n o t
f e d a n d f o r in fa n ts receiving each t y p e o f f e e d i n g ; eight cities

G en eral T able

Deaths of infants
not fed

Deaths of infants fed in each specified way
Breast fed

Total
Nationality of mother

Ratio of
actual
Ex
to ex
Ac
tual pected 1 pected
(per
cent)

Ac
tual

Ratio of
actual
to ex Ac
Ex
pected 2 pected tual
(per
cent)

Ratio of
actual
Ex
to ex
pected pected
(per
cent)

Total.......... ...... .........

645

545.0

100.0

2,010

2,010.0

100.0

688

687.9

100.0

White..........................................

502

510.4

98.4

1,828

1,893.9

96.5

619

646.0

95.8

Native. .............................
Foreign born.......................
Italian._______________
Jewish_______ ______ _
French-Canadian_____
German______________
Polish_________ _____ _
Portuguese.................
Other..... ........................

287
215
36
20
34
14
28
12
71

287.2
223.2
33.8
29.3
25.5
18.4
30.0
15.9
70.3

99.9
96.3
106.5
68.3
133.3
76.1
93.3
75.5
101.0

848
980
112
46
150
66
171
122
313

1,116. 4
777.5
100.9
89.5
118.4
66.5
87.4
64.6
250.0
.2

76.0
126.0
111.0
51.4
126.7
99.2
195.7
188.9
125.2

251
368
65
22
36
23
71
25
126

356.9
289.1
49.3
40.3
25.4
22.7
41.9
17.9
91.6

70.3
127.3
131.8
54.6
141.7
101.3
169.5
139.7
137.6

Colored___ __________________

34.6

124.3

182

116.1

156.8

41.9

164.7

Deaths of infants fed in each specified way—Continued

Partly breast fed
Nationality of mother
Ac
tual

Total_______________

269

Ratio of
actual
Ex
to ex
pected pected
(per
cent)
269.1

100.0

Type of feeding not
reported

Artificially fed

Ac
tual

Ex
pected

1,047

1,047.0

Ratio of
actual
to ex Ac
pected tual
(per
cent)
100.0

Ratio of
actual
Ex
to ex
pected pected
(per
cent)
6.1

100.0

White___ _____ ________ ______

240

245.7

97.7

963

996.2

96.7

6.1

100.0

Native. ..............................
Foreign born........................

91
149
17
6
19
8
39
24
36

126.8
118.9
17.1
21.8
9.3
11.7
18.0
9.6
31.4

71.8
125.3
99.4
27.5
204.3
68.4
216.7
250.0
114.6

503
460
30
16
95
35
60
73
151

630.4
365.8
34.6
26.5
83.6
31.7
26.3
37.1
125.9
.1

79.8
125.8
86.7
60.4
113. 6
110.4
228.1
196.8
119.9

3
3

2.3
3.8

130.4
78.9

222.2

.4
1.3

76.9

23.4

123.9

50.8

165.4

Jewish............................
French-Canadian_____
German................... ......
Polish.............................
Other..............................
Colored............. ........................

1 Expected at average rate for infants not fed.
2 Expected at average rate for infants receiving the same type of feeding.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

1.2

A P P E N D IX

D .—

GENERAL

221

TABLES

T a b l e 75.— C olor a n d n a tio n a lity o f m other, b y average n u m b er
;person s per r o o m ; in fa n ts i n seven dities w ho survived tw o w eek s 1

G eneral

Infants who survived two weeks1
Average number of persons per room

Color and nationality of mother
Total

Total________________________
White......................................
Native____ _____________________
Foreign bom ..........................................
Italian...............................
Jewish__________ __________
French-Canadian.........................
German________ ____ ________
Polish.....................................
Portuguese............. ............ ..........
Other.........................................
Not reported_______ ____ _______
Colored.............................................

Less than One, less Two, less Three
than
one
than two
and over
three

Not re
ported

20,698

10,837

8,558

1,040

132

131

19,337

10,218

7,877

998

120

124

10,896
8,441
1,303
1,186
L026
707
1,119
652
2,446
2

7,286
2,932
311
491
415
343
140
179
1,052
1

3,396
4,481
779
608
551
326
637
390
1,189
1

168
830
194
85
53
28
239
65
166

14
106
14

32
92
5

2
6
47
6
29

5
4
56
12
10

1,361

619

681

1 Excluding a small number of infants who did not live two weeks in dwelling of residence (Baltimore).
G eneral T able

76.—

E a r n in g s o f fa th er, b y color an d n a tio n a lity o f m oth er; live
births i n seven cities

Live births—
To white mothers
Earnings of
father
Total

To
col
ored
Total Native
moth
Not
ers
Jew FrenchGer Pol Por
Total Ital
tu Other re
ian
ish Cana man ish
dian
guese
ported
Foreign bom

Total____ 21,536 20,085 11,323 8,762 1,355 1,223
Less than $450..
$450-$549...........
$550-$649..........
$650-$849______
$850-$1,049_____
$1,050-$1,249___
$1,250 and over..
No earnings___
Not reported-. .

3,085
2,827
2,908
5,050
3,345
1,391
2,252
313
365

2,538
2,430
2,737
4,904
3,303
1,377
2,237
239
320

653
926
1,390
2,914
2,291
1,070
1,770
128
181

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

1,885
1,504
1,347
1,990
1,012
307
467
111
139

441
298
198
221
98
28
33
18
20

210
162
144
253
167
58
169
28
32

1,074

729 1,167

75 84
180 79
197 130
358 211
159 117
28 37
54
55
12
7
11
9

408
264
224
160
56
11
9
18
17

669 2,543
267
164
89
95
30
4
5
5
10

400
867
365
691
385
140
142
23
40

1,451
547

1
1

146
42
14
15
74
45

222

CAU SAL

FACTORS

IN F A N T

M O R T A L IT Y

77.— A v era g e p er ca p ita in c o m e f r o m fa th e r’ s ea rn in g s, b y color
and n a tio n a lity o f m o th er; live births i n seven cities 1

G en eral T able

Live births 1
Average per capita income from father’s earnings

Color and nationality of mother
Total

Less than
$50

$50-$99

$400
$100-$199 $200-$399 and
over

Total.

18,587

227

2,948

6,900

8,000

White_________ ________

17,273

203

2,580

6,268

7,716

506

9,238
8,035
1,281
993
997
657
1,106
664
2,336
1

49
154
24
20
30
15
28
21
16

746
1,834
423
210
219
115
324
176
367

2,859
3,409
556
419
393
252
522
334
933

5,161
2,555
267
333
352
255
231
133
984

423
83
11
11
3
20
1

1,314

368

632

284

Native________ ____
Foreign born..............
Italian...........
Jewish_________
French-Canadian.
German________
Polish__________
Portuguese_____
Other__________
Not reported.......
Colored.

512

36
1

1 Excluding live births in families with father’s earnings $1,250 and over, earnings not reported, and no
father’s earnings, a few cases in which number in family was not reported, and those in which infant lived
in an institution.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

T a b l e 78.

Month of life

Infant
survivors
at begin
ning of
specified
month

Less than 1

Number

172
184
157
154
148
150
125
105
110
105
70
86

Rate

8.3
9.0
7.7
7.6
7.4
7.5
6.3
5.4
5.6
5.4
3.6
4.5

1, less than 2

Deaths during
Survivors %
month
at begin
ning of
month
Number
Rate
10,837
10,765
10,700
10,650
10,583
10,529
10,487
10,444
10,404
10,364
10,325
10,300

72
65
50
67
54
42
43
40
40
39
25
28

6.6
6.0
4.7
6.3
5.1
4.0
4.1
3.8
3.8
3.8
2.4
2.7

Survivors
at begin
ning of
month

8,558
8,480
8,378
8,292
8,225
8,146
8,060
7,994
7,940
7,880
7,825
7,793

2 and over

Deaths during
month
Number
78
102
86
67
79
86
66
54
60
55
32
47

9.1
12.0
10.3
8.1
9.6
10.6
8.2
6.8
7.6
7.0
4.1
6.0

1,172
1,152
1,138
1,119
1,106
L092
1,073
1, 058
l|048
1,041
1, 031
lj 022

Déaths during
month
Number
20
14
19
13
14
19
15
10
7
10
9
9

Rate
17.1
12. 2
16.7
11. 6
12. 7
17. 4
14. 0
9. 5
6.7
9. fi
. 8.7
8.8

Survivors
at begin
ning of
month
181
129
126
124
117
llfi
118
112
111

Deaths during
month
Number

Rate

2
3
2
7
1
3

107

103

19.4

TABLES

* Excluding a small number of infants who did not live two weeks in dwelling of residence (Baltimore).
3 Surviving at commencement of third week of life; see also note L

Rate

Survivors
at begin
ning of
month

Not reported

D . ------ G E N E R A L

2 20,698
20,526
20,342
20,185
20,031
19,883
19,733
19,608
19,503
19,393
19,288
19,218

Average number of persons per room

Deaths during
month

A P P E N D IX

First2.........................
Second........................
Third _____________
Fourth........................
Fifth_______________
Sixth_______ _______
Seventh................. .
Eighth_____________
Ninth______________
Tenth....... ................
Eleventh___________
Twelfth.................

-M o n t h l y death rates, b y m on th o f life a n d average n u m b e r o f p erson s p er r o o m ; in fa n ts i n seven cities w ho survived
tw o w eeks 1

fcO

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

224

CAU SAL

FACTORS

IN F A N T

M O R T A L IT Y

G e n e r a l T a b l e 7 9 .— P revalen ce o f artificial fe e d in g i n selected m o n th s, h y average
n u m b er o f p erson s p er r o o m ; in fa n ts i n seven cities w ho survived tw o w eeks

Infants surviving at
beginning of third
month

Infants surviving at
beginning of sixth
month

Artificially fed
during
third month

Artificially fed
during
sixth month

Average number of persons
per room
Total

Total
Num
ber

Per
cent

Infants surviving at
beginning of ninth
month
Artificially fed
during
ninth month
Total

Num
ber

Per
cent

Num
ber

Per
cent

Total............................. 20,342

4,255

20.9

19,883

5,901

29.7

19,503

6,970

35.7

Less than 1________________ 10,700
1, less than 2.______________ 8,378
2, less than 3........................... 1,012
3 and over............................... . 126
126
Not reported................... ......

2,393
1,680
144
13
25

22.4
20.1
14.2
10.3
19.8

10,529
8,146
973
119
116

3,348
2,288
212
23
30

31.8
28.1
21.8
19.3
25.9

10,404
7,940
934
114
111

3,983
2,681
246
26
34

38.3
33.8
26.3
22.8
30.6

1 Excluding a small number of infants who lived less than two weeks in dwelling of residence (Baltimore).
G

eneral

able

8 0 .— E a r n in g s o f fa th e r , b y average n u m b er o f p e rso n s p er r o o m ;
in fa n ts i n seven cities w ho survived tw o w eek s 1

Infants who survived two weeks1
Average number of persons per room

Earnings of father
Total

Less
than 1

1, less
than 2

2, less
than 3

3 and
over

Not
reported

Total...................................................

20,698

10,837

8,558

1,040

132

131

Less than $450.______ __________________
$450-$549.......................................................
$550-$649.......................................................
$650-$849_____________ _________________
$850-$l,049...................... ........................
$1,050-$1,249._.____________________ ____
$1,250 and over.......... ..................... .............
No earnings.................................................
N ot reported______________ ______ _____ _

2,943
2,719
2,799
4,856
3,229
1,347
2,173
291
341

772
994
1,184
2,654
2,184
991
1,788
96
174

1,703
1,449
1,402
2,022
968
340
369
157
148

373
224
165
148
65
12
11
30
12

48
29
22
19
5
1
1
3
4

47
23
26
13
7
3
4
5
3

1 Excluding a small number of infants who did not live two weeks in dwelling of residence (Baltimore).
G

T a b l e 8 1 .— A v era g e n u m b er o f p e rso n s p er r o o m , b y per ca p ita in co m e
f r o m fa th e r’ s e a r n in g s; in fa n ts i n seven cities w ho survived tw o w eek s 1

eneral

Infants who survived two weeks 1
Average number of persons per room

Per capita income from father’s earnings
Total

Less
than 1

1, less
than 2

T otal..

17,874

8,772

7,875

Less than $50.
$50-$99..........
$100-$199.......
$200-$399.......
$400 and over,

218
2,831
6,652
7,678
495

280
2,407
5,639
446

133
2,005
3,811
1,883
43

2, less
than 3

i Excluding a small number of infants who did not live two weeks in dwelling of residence (Baltimore).
Excluding also infants in the “ $1,250 and over,” “ no earnings,” and “ earnings not reported” groups, and
those for whom the number in family was not reported.

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Federal Reserve Bank of St. Louis

225

A P P E N D IX D .-----G E N E R A L T A B L E S
G

eneral

8 2 . — Monthly death rates, by month o f infant’ s life and employ
ment o f mother during pregnancy; infants in eight cities

able

Twelfth

Tenth

Eleventh

g
Jj
s

Ninth

Seventh

•g

Eighth

1 Fourth

Third

| Second

Employment of mother
during pregnancy

| First

Monthly death rates
Infant
Live Infant mor
births deaths tality
rates

Total....... ..................... 22,967

2,555

111.2 44.8 9.3 8.1 8.0 7.7 7.4 6.3 5.8 5.7 5.3 3.9 4.5

Employed away from home.. 3,084
Employed at hom e............... 3,788
Not employed_____________ 16,089
Not reported.........................
6

543
434
1,576
2

176.1 63.2 15.6 14.1 14.6 12.3 13.9 13.7 9.4 10.7 9.2 5.8 8.2
114.6 36.7 11.0 9.1 10.1 8.8 7.4 7.8 7.8 6.4 6.5 5.0 4.2
98.0 43.1 7.7 6.7 6.3 6.6 6.1 4.6 4.7 4.6 4.3 3.3 3.9

eneral

able

8 3 .—

Proportion o f plural births, by employment o f mother dur
ing pregnancy; live births in eight cities
Live births
Plural births

Employment of mother during pregnancy
Total

Number

Total___________ _____ ___ ______ ______
Employed away from home______________ _____
Employed at home___ __________________
Not employed__________________ .
Not reported__________________________________
•
G

eneral

Per 1,000
live
births

22,967

529

23.0

3,084
3,788
16,089
6

71
91
367

23.0
24.0
22.8

8 4 . — Prevalence o f artificial feeding, by month o f life and employ
ment o f mother during pregnancy; infants in eight cities

able

Infants surviving at
beginning of third
month

Infants surviving at
beginning of sixth
month

Artificially fed
during third
month

Artificially fed
during sixth
month

Employment of mother
during pregnancy
Total

Total
Num
ber

Per
cent

Infants surviving at
beginning of ninth
month
Artificially fed
during ninth
month
Total

Num
ber

Per
cent

Num
ber

Per
cent

Total________________ 21,735

4,431

20.4

21,222

6,145

29.0

20,812

7,268

34.9

Away from home................. . 2,844
At home........ ......................... 3,609
Not employed........................ 15,276
Employment not reported...
6

630
603
3,197
1

22.2
16.7
20.9
16.7

2,729
3,509
14,979
5

911
849
4,383
1

33.4
24.2
29.3
20.0

2,629
3,429
14,749
5

1,060
1,063
5,140
5

40.3
31.0
34.8
100.0

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

226
G

CAU SAL FACTORS IN

I N F A N T M O R T A L IT Y

T a b l e 8 5 . — Employment o f mother away from home, by interval between
cessation of work and confinement, and earnings o f father; live births in seven
cities

eneral

Live births—
To mothers employed away from home
Interval between cessation of work and confinement

Earnings of father
Total
Total

Per
cent

No interval

Less than 1
month

1 month and
over

Not
reported

Num Per Num Per Num Per Num Per
ber
cent1 ber cent1 ber
cent1 ber cent1
Total__________

21,536

3,071

14.3

217

7.1

192

6.3

2,634

85.8

0.9

Less than $450_______
$450-$549____________
$550-$649_....................
$650-$849.... ..................
$850-$1,049___________
$1,O5O-$1,240...............
$1,250 and over_______
No earnings_________
Not reported-'............

3,085
2,827
2,908
5,050
3,345
1,391

872
649
529
547
202
42
43
117
70

28.3
23.0
18.2
10.8
6.0
3.0
1.9
37.4
19.2

88
51
16
13
11
2
7
22
7

10.1
7.9
3.0
2.4
5.4

76
37
28
20
5

8.7
5.7
5.3
3.7
2.5

80.8
85.7
90.4
92.5
91.6

.3
.8
1.3
1.5
.5

2
16
8

3
5
7
8
1
1
1

18.8
10.0

13.7
11.4

705
556
478
506
185
39
33
79
53

2.9

2,252
313
365

67.5
75.7

1 Not shown where base is less than 50. Percentages based on live births to mothers employed away
from home.
G

eneral

a b l e 8 6 . — Employment o f mother during pregnancy, by her employ
ment during first year o f infant’ s life; infants in eight cities

Live births—

•#

To
mothers
em
ployed
away
from
home
during
preg
nancy

To
mothers
em
ployed
at home
during
preg
nancy

22,967

3,084

3,788

16,095

1,742
4,337
116,887
1

1,285
424
1,375

96
3,218
474

361
695
15,038
1

Employment during first year of infant’s life
Total

Total

........................ . .........................

1Including 6 cases for which it was not reported whether or not the mother was employed.
8 Place of employment not reported.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

To
mothers
not em
ployed
during
preg
nancy

227

A P P E N D I X D .-----G E N E R A L T A B L E S

G e n e r a l T a b l e 87 .— Type o f feeding in month in which mother went to work, by

place o f her employment; infants in eight cities surviving when mothers went to
work
Infants whose mothers went to work in specified month

Month of infant’s life when
mother resumed work

Partly breast Artificially fed
Breast fed
fed during
Sur
during month
during month
month
vivors Deaths
when during
mothers month
went to
Deaths
Sur Deaths Sur Deaths
work
during Sur during
vivors during
month vivors month vivors month

Type of
feeding
not re
ported

Mother employed away from
home during first year of
infant’s life______________

1,742

545

575
8
55
63
68
51
44
63
49
53
40
58
23

618
21
80
71
101
57
62
49
40
59
38
20
18
2

Sur
vivors

First month___________
Second month.................
Third month__________
Fourth month_________
Fifth month___________
Sixth month___________
Seventh month________
Eighth month_________
Ninth month____ _____
Tenth month__________
Eleventh month....... ......
Twelfth month-----------Not reported---------------Mother employed at home
during first year of infant’s
life__________________■___

4,337

3,224

488

580

First month.....................
Second month.................
Third month__________
Fourth month_________
Fifth month___________
Sixth month...................
Seventh month----------Eighth month_________
Ninth month..................
Tenth month-------------Eleventh m o n th .._____
Twelfth month________
Not reported.............. . . .

2,428
629
278
202
144
107
132
89
77
90
72
30
59

22
3
2

2,141
483
195
129
86
54
56
24
16
18
9
2
11

15
1

89
50
34
34
29
26
41
41
40
48
36
20

2
1

197
96
48
39
29
27
35
24
21
24
27
8
5

5
1
2

Place of mother’s employ
ment not reported: Age
not reported_____________

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

105
243
233
242
143
151
144
111
138
99
84
46
3

1
1
3
1
1

76
107
99
73
35
44
31
22
26
21
6
5

1
1
3

1
1

1
43

228
G

C A U S A L F A C T O R S TN I N F A N T M O R T A L IT Y

T a b l e 8 8 . — Type o f feeding, by month o f infant’ s life and place o f mother’s
employment; infants in eight cities whose mothers were employed during some
preceding month o f infant’s life

eneral

Infants whose mothers were employed during some preceding month of
infant’s life
Type
of
Partly breast Artificially fed
Breast fed
fed during
during specified feeding
during specified
month
not re
specified month
month
ported

Sur
vivors
at
begin Deaths
ning of during
Sur
Sur
Sur
each month Sur
vivors Deaths vivors Deaths vivors Deaths vivors
speci
at
at
at
at
fied
during
during
during
month
begin month begin month begin month begin
ning of
ning of
ning of
ning of
month
month
month
month

Month of infant’s life, and
place of employment and
nationality of mother

Mother employed away from
home during first year of
infant’s life:

Fifth month___________
Sixth month............... .
Seventh month............

Twelfth month......... ......
Mother employed at home
during first year of infant’s
life:
Second month.................
Third month..................
Fourth month....... .........
Fifth month___________
Sixth month.____ ______
Seventh month...............
Eighth m onth................
Ninth month................. .
Tenth month...................
Eleventh month_______
Twelfth month________

eneral

able

105
347
571
804
931
1,054
1,171
1,267
1,384
1,467
1,542

1
8
9
15
25
27
14
21
16
8
17

36
79
101
126
132
104
102
81
68
66
59

2,406
3,005
3,258
3,433
3,553
3,639
3,749
3,811
3,866
3,933
3,983

27
23
27
24
21
22
27
22
22
22
17

1,971
2,226
2,123
2,039
1,901
1,531
1,328
1,067
839
659
560

22
105
186
259
300
364
431
485
536
569
611

4
3
4
4
7
3
4
5
2
4

47
162
283
418
498
584
635
698
775
827
867

1
4
6
10
19
19
11
17
11
6
11

1
1
1
1
2
3
3
5
5
5

13 . 150
9
286
5
463
4
623
791
3
1,144
7
7
1,350
5
1,565
3
1,725
5
1,864
3
1,917

3
4
5
4
3
5
5
5
5
5
5

284
492
670
769
859
962
1,069
1,177
1,300
1,408
1,505

11
10
17
16
15
10
15
12
14
12
9

1
1
2
2
2
2
2
2
2
2
1

1
2
1

8 9 .—

Type o f feeding during first nine months o f life, by employ
ment o f mother; infants in eight cities
Months lived from birth to end of ninth

E m p l o y m e n t of
mo t h e r d ur i ng
first year of in
fant’s life

Months of breast
feeding

Months of partly
breast feeding

Total
Number

Per cent Number

Months of artificial Feeding
feeding
not re
ported
(num
Per cent . Number Per cent ber) *

Total............... 192,212.50

110,384.00

57.4

33,904.50

17.60

47,842.00

24.9

82.0

Employed
away
6,891.00
from home............
Employed at home.. 27,585.25
Not employed1____ 157,736. 25

977.25
14,680. 75
94,726. 00

14.2
53.2
60.1

2,360.30
6, 502. 25
25,042. 00

34.25
23.60
15.90

3, 540. 00
6,387. 75
37,914. 25

51.4
23.2
24.0

13.5
14.5
54.0

1 Including not reported as to employment.
2 Per cent not shown for “ not reported ” group because not significant.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

229

A P P E N D I X D .-----G E N E R A L. T A B L E S
G

T a b l e 9 0 . — Earnings o f mother, by earnings o f father; infants in seven
cities whose mothers were employed during first year o f infant’s life

eneral

Live births to mothers employed during first year of infant’s life
Earnings of father

Earnings of mother
Total

Less
than
$450

$450$549

$550$649

$650$849

$850- $1,050$1,049 $1,249

$1,250
and
over

No
earn
ings

Not
re
ported

Total________

6,384

1,697

1,178

880

1,179

610

205

262

220

153

Less than $150_____
$150-$249............ ......
$250-$349...................
$350-$549...................
$550 and over........
Not reported....... .

3,077
1,301
692
465
155
694

943
390
152
97
25
90

'644
210
117
-100
20
87

439
177
93
80
20
71

544
237
152
92
39
115

251
116
74
45
23
101

76
51
29
8
7
34

60
28
27
15
12
120

77
70
34
21
7
11

43
22
14
7
2
65

T a b l e 9 1 . — Earnings o f children in fam ily, by earnings o f father; live
births in seven cities in fam ilies in which one or more children worked during
year following the births

eneral

Live births in families in which one or more children worked
Earnings of father

Earnings of
children
Total

Less
than
$450

$450$549

$550$649

$650$849

$850- $1,050$1,049 $1,249

$1,250
and
over

No
earn
ings

Not
re
ported

Total ............

1,003

241

128

158

199

123

Less than $50............
$50-$149.....................
$150-$249...................
$250-$349...................
$350 and over............
Not reported.......... .

84
133
144
133
421
88

32
38
34
41
79
17

8
19
22
14
57
8

19
18
22
20
69
10

11
26
32
23
89
18

4
12
14
11
69
' 13

3
10
7
9
22
4

4
6
9
9
21
7

3
2
4
7
2

3
i
2
2
8
9

96515°—25t----- it)

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

230
G

CAUSAL FACTORS IN

eneral

able

IN F A N T M O R T A L IT Y

9 2 .—

Infant mortality rates, by total annual income o f fam ily and
earnings o f father; live births in seven cities
Total annual income of family
Total

Earnings of father

Less
than
$550

$550$649

$650$849

$850- $1,050- $1,250
and
$1,049 $1,249
over

No
earn
ings

Not re
ported

LIVE BIRTHS

Total.......

21,536

4,281

2,739

5,134

Less than $450..
$450-$549...........
$550-$649...........
$650-$849...........
$850-$l, 049____
$1,050-$1,249__
$1,250 and over.
No earnings___
N ot reported__

3,085
2,827
2,908
5,050
3,345
1,301
2,252
313
365

2,364
1,713

281
450

253
379‘
525
3,965

2 ,0 0 0

202
2

3,787

1,903

3,039

153
194
613
2,752

28
50
79
237
322
1,183

42
46
72
182
245
198
2,240
7
7

593
49
36
38
53
26
10
12

17
352

105

INFANT DEATHS

Total___

2,368

587

321

601

359

152

236

515
355
339
543
277
89
133

354
184

46
60
213

17
23
32
77

Less than $450..
$450-$549...........
$550-$649...........
$650-$849...........
$850-$l, 049____
$1,050-$1,249...
$1,250 and over.
No earnings___
Not reported__

60
75
396

5
30
32
72.

210

30
31
14
132

17
7

4
3
1

4
51

51
INFANT MORTALITY RATES

Total____
Less than $450..
$450-$549— ......
$550-$649..........
$650-$849______
$850-$1,049____
$1,050-$l, 249__
$1,250 and over.
N o earnings___
Not reported...
1

110 .0

137.1

117.2

117.1

94.8

79.9

166. 9
125. 6
116. 6
107. 5
82. 8
64. 0
59. 1
210. 9
139.7

149.7
107.4

163.7
133.3
106.5

260.9
158.3
142.9
99.9

250.0
150.3
164.9
125.6
76.3

0
1 2 0 .0

242.6

63.3
126. 6
99.4
60.9
Jl'

77.7

116.7

83.3
164.8
126. 5
70. 7
58.9

177.1
0
i
0

0
0

188.7

116.7

0
0
0
0

144.9

Not shown where base is less than 50.

eneral

able

9 3 .—

Earnings of father, by average 'per capita income from
father’ s earnings; live births in seven cities
Live births
In families with specified average per capita income from father’s earnings

Earnings of father
Total

Less
than
$50

$50$74

$75$99

$100 $124

$125$149

$150$199

$2 0 0 $299

$300- $400- $600$399 $599 $799

Total___________

18,587

227

1,294

1,654

2,166

2,051

2,683

4,765

3,235

190
31

801
270
150
71

517
552
357
185
41

698
460
325
526
123

827

$450-$549__
$550-$649-_................... .
$650-$849_ .....................
$850-$!, 049
$1,050-$l, 249..................

3,077
2,826
2,905
5,047
3,341
1,391

44
845
936
1,238
1,339
363

1,691
1,196
339

659
478
560
323
31

641
764
313
138

503

9
12
12

479

4
5

1 Excluding live births in the “ $1,250 and over,” “ no^earnings,” and “ earnings not reported” groups;
also a few cases in which the number in the family was not reported and those in which the infant was the
only member of the family.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

231

A P P E N D I X D .— G E N E R A L T A B L E S
G

eneral

9 4 . — Infant

mortality rates, by cause o f death and economic
need; 1 live births in seven cities 2

able

Infant deaths

Average per capita in
come from father’s
earnings

Live
births

Num Infant
ber mortality
rates

From gastric
and intestinal
diseases

Num Infant Num Infant Num Infant
ber mortality
ber mortality
ber mortality
rates
rates
rates

Total____________

18,587

2,117

113.9

635

Less than $50__________
$50-$99______________
$100-$199..........................
$200-$399__________
$400 and over__________

227
2,948
6,900

49
418
850
769
31

215.9
141.8
123.2
96.1
60.5

25
146
274
186
4

8 ,0 0 0

512

From respiratory From malforma
diseases
tions

34.2

379

20.4

1 1 0 .1

49.5
39.7
23.3
. 7.8

87
168
113
3

35.2
29.5
243
14. 1
5.9

41
5.2
4.5

36
36

Infant deaths—Continued ‘

Average per capita
income from fath
er’s earnings

From early
infancy

From epidemic
and other
communicable
diseases

From external
causes

From diseases
ill defined
and unknown

From other
causes

Num Infant Num Infant Num Infant Num Infant Num Infant
ber mortality
ber mortality
ber mortality
ber. mortality
ber mortality
rates
rates
rates
rates
rates
Total________

669

36.0

130

7.0

Less than $50______
$50-$99....................
$100-$199__________
$200-$399_______
$400 and over______

441
37.0
35.9
36.0
27.3

5
27
52
44

2 2 .0

109
248
288
14

9.2
7.5
5.5
3.9

0 .6

.7
.3
.9

2 .0

2
2

16
20

2.5

162

8.7

3.4
2.3
2.5

I
25
54
75
7

78
94
13.7

1 As measured by the average per capita income from father’s earnings.
’ E lu d in g births in the “ $1,250 and over,” “ no earnings,” and “ earnings not reported” groups. See
Table 134, p. 148.
■>. r

Monthly death rates, by month o f infant’ s life and earnings
o f father; infants in seven cities

9.0

7.9

7.7

7.4

7.6

6.3

55.8 15.1 13.6 15.2 12.9
46.0 10.4 1 1 .2 8.3 5.7
43.3 1 0 .8 6.5 7.3 8 . 8
46.5 8.9 8.4 7.4 9.4
38.0 6.5 5.0 5.0 3.2
33.1 3.0 5.2 3.0 4.5
38.2 3.7 1.9 2 . 8 1.4
60.7 3.4 13.7 24 2 248
41.1 2 0 .0 11.7 8 . 8 8.9

11.3
12.7
7.4
4.9

1 2 .1

6 .0
6 .8

2 .2

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

9.3
9.7
4.1

2.3
1.9 2.3
40.0 22.7
3.0 6 . 0

Twelfth

44 4

166.9
125.6
116.6
107.5
82.8
64.0
59.1
210.9
139.7

Eleventh

Fifth

1 1 0 .0

515
355
339
543
277
89
133

Ninth

Fourth

2,368

3,085
2,827
2,908
5,050
3,345
1,391
2,252
313
365

Tenth

Third

21,536

Sixth

Second

Total________
Less than $450_____
$450-$549 ................
$550-$649_................
$650-$849.... .............
$850-$l,049________
$1,050-$1,249_______
$1,250 and over____
No earnings_______
-Not reported______

Eighth

Monthly death rates

First

Earnings of father

9 5 .—

Seventh

able

Infant mortal
ity rates

Infant deaths

eneral

Live births

5.4 5.7 5.5 3.7 4 6
1 0 .0

4.7
9.1
4 1
3.8
1.5
1.9
1 1 .6
1 2 .1

9.4 1 1 .0 8 . 1 5. 8
4 7 6 .7 4.8 8 . 0
7.3 5.0 3.1 4.3
5.7 4.2 3. 5 5.3
5.5 6 . 1 1.9 2.3
. 8 3.1
. 8 1.5
1.4 1.4 1.4 1.9
3.9 3.9 7.9 15.9
21.5 3.1 9.4 3.2

232
G

C A U S A L F A C T O R S IFF IF TF A U T M O R T A L IT Y

eneral

9 6 .—

able

Proportion o f plural births, by earnings of father; live
births in seven cities

Live births

Plural births

Earnings of father
Total

Number

Total

Per 1,000
live
births

Total.... ........

21, 536

482

22.4

Less than $450 ___
$450-$549.................
$550-$649.... .............
$650-$849_________

3,085
2,827
2,908
5,050

73
74
67
105

23.7
26.2
23.0

Plural births

Earnings of father

$850-$1,049.........
$1,050-$1,249............
$1,250 and over____
No earnings_______
Not reported______

3,345
1,391
2,252
313
365

Number

Per 1,000
live
births

75
26
52

22.4
18.7
23.1
19.2

1 1 .0

2 0 .8

T a b l e 9 7 . — Proportion of births to mothers who died at or within one
year after confinement, by earnings of father; live births in seven cities

eneral

Live births—

Live births-

To mothers who
died at or within
one year after
confinement

Earnings of father
Total

Per 1,000
Number live
births

To mothers who
died at or within
one year after
confinement
Per 1,000
Number live
births

Total.............

21,536

132

6 .1

$850-$l,049

3,345

4.2

Less than $450........
$450-$549_________
$550-$649_________
$650-$849_________

3,085
2,827
2,908
5; 050

7.1
5.7
5.8
7.3

$1,250 and over.......

2,252
313
365

10
3

4.4
9 6
24.7

16
17
37

T a b l e 9 8 . — Relative infant mortality, by earnings o f father, when
influence o f age o f mother and order o f birth, and of interval since preceding birth
is eliminated; single live births in seven cities and live births in Baltimore

eneral

Deaths of single-born infants; seven cities

Earnings of father
Actual

Ratio of
rate in
Ratio of specified
Expected1 actual to
to
expected group
average
rate

Infant deaths; Baltimore

Actual

Ratio of
Ratio of rate in
specified
Expected1 actual to
to
expected group
average
rate

T otal...............

2,196

2,196.3

1 0 0 .0

845

845.0

1 0 0 .0

Less than $450...........
$450-$549 ................ .
$550-$649.....................
$650-$849___________
$850-$l,049__________
$1,050-$1,249________
$1,250 and over______
No earnings..............
Not reported............ .

480
326
305
506
257
84
125
64
49

336.8
299.7
301.7
512.1
329.2
135.7
209.6.
. 33.4
38.1

142.5
108.8

152.8
113.5
103.0
98.0
75.4
59.0
54.5

187
142
119
177
79
33
53
33

133.3
121.5
118.4
183.5
119.4
49.3
87.2
15.6
16.8

140.3
116.9
100.5
96.5

151.4
114.0
105.1
92.8
69.1
64.3
62.5
200.7
135.5

1 0 1 .1

98.8
78.1
61.9
59.6
191.6
128.6

2 0 0 .0

130.1

6 6 .1

66.9
60.8
211.4
131.1

i Expected if the rates for each interval were applied to the live births classified by earnings of father and
interval after preceding birth.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

233

A P P E N D IX D .-----G E N E R A L T A B L E S
G

eneral

9 9 . — Prevalence o f breast and artificial feeding, by month of
infant’ s life and earnings o f father; infants in eight cities

able

Infants surviving at beginning of each specified month
Month of infant’s life and
earnings of father

T ota l 1

Breast fed during
month
Number

Less than $450:
F irs t........................ ...........
Second.... ..................... ........
Third____________________
Fourth___________________
Fifth____ ________________
Sixth____________________
Seventh___________ ______
Eighth__ ______ __________
Ninth____________________
Tenth___________________
Eleventh_________________
Twelfth......... ................ ......
$450-$549:
First......................................
Second_____________ _____
Third ..................................
Fourth___________________
Fifth____________________
Sixth____________________
Seventh-- _______________
Eighth_______ _______ ____
Ninth___ - _______ ________
Tenth________ ________ _
Eleventh_________________
Twelfth............................. .
$550-$649:
First_____________________
Second___________________
Third. __________________
Fourth___________________
Fifth____________________
Sixth___________________
Seventh.. _______________
Eighth___________________
Ninth__________________ Tenth___________________
Eleventh_________________
Twelfth____________ - __
$650-$849:
F ir s t ...................... .............
Second___________________
Third ___________________
Fourth___________________
Fifth____________________
Sixth____________________
Seventh___ ____ . . . _____
E ig h th ...________________
Ninth____________________
Tenth____________________
Eleventh_________________
Twelfth_________________ _
$850-$l,049:
First __________ '......... ......
Second____ _____ _________
Third_______________ ____
Fourth__________ ________
Fifth____________________
Sixth____________________
Seventh__ _______________
Eighth___________________
Ninth...................................
Tenth____________ _______
Eleventh_____________ . . .
Twelfth_____ ____________
$1,050-$1,249:
First..................... ................
Second...................... ...........
Third________ ____________
Fourth................. ................
Fifth____ _______________ „
Sixth....... ...... ......................
Seventh__________________
Eighth___________________
Ninth_______________ -----Tenth____________________
Eleventh_________________
Twelfth................................

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Partly breast fed
during month

Per cent Number

Artificially fed dur
ing month

Per cent Number

3,004
2,913
2,869
2,830
2,787
2,751
2,720
2,687
2,660
2,635
2,606
2,585

2,619
2,302
2,039
1,764
1,564
1,372
1,041
869
691
540
426
368

87.2
79.0
71.1
62.3
56.1
49.9
38.3
32.3
26.0
20.5
16.3
14.2

2,759
2,697
2,669
2,639
2,617
2,602
2,569
2,545
2,533
2,521
2,504
2,492

2,416
2,157
1,932
1,638
1,476
1,317
855
679
522
416
347

87.6
80.0
72.4
62.1
56.4
50.6
39.7
33.6
26.8
20.7
16.6
13.9

103
199
277
416
519
680
849
959
1,075
1,153
1,191

2,843
2,782
2,752
2,734
2,714
2,690
2,670
2,644
2,620
2,601
2,588
2,580

2,466
2,172
1,964
1,695
1,549
1,370
1,061
904
729
543
417
360

86.7
78.1
71.4
62.0
57.1
50.9
39. r
34.2
27.8
20.9
16.1
14.0

92
179
224
347
431
541
774
874
999
1,113
. 1,181
1,179

29.0
33.1
38.1
42.8
45.6
45.7

892
945
990
1,041

4,930
4,815
4,772
4,732
4,697
4,653
4,630
4,611
4,592
4,566
4,547
4,531

4,233
3,756
3,379
2,970
2,718
2,440
1,952
1,678
1,363

85.9
78.0
70.8
62.8
57.9
52.4
42.2
36.4
29.7
22.4
17.3
13.9

134
239
341
507
637
799
1,174
1,380
1,593
1,804
1,941
1,978

2.7
5.0
7.1
10.7
13.6
17.2
25.4
29.9
34.7
39.5
42.7
43.7

560
817"
1,050
1,253
1, 340
1,412
1,502
1,551
1,634
1,738
1,817
1,921

3,266
3,218
3,197
3,181
3,165
3,155
3,136
3,129
3,117
3,100
3,081
3,075

2,810
2,508
2,304
2,054
1,887
1,694
1,360
1,173
937
683
521
422

1,362
1,345
1,341
1,334
1,330
1,324
1,315
1,312
1,310
1,309
1,305
1,304

1,170
1,044
942
807
747
677
554
466
354
245
173
145

1 ,0 2 1

1 ,0 2 2

787
630

8 6 .0

77.9
72.1
G4.6
59.6
53.7
43.4
37.5
30.1
2 2 .0

16.9
13.7
85.9
77.6
70.2
60.5
56.2
51.1
42.1
35.5
27.0
18.7
13.3
1 1 .1

108
202

317
447
556
668

900
1,006
1,113
1,196
1,238
1,238

1 ,2 0 0

3.6
6.9
15.8
19.9
24.3
33.1
37.4
41.8
45.4
47.5
47.9

273
406
510
616
664
707
775
808
854
896
939
976

3.7
7.4
10.4
15.8
19.8
24.2
33.0
37.7
42.4
45.7
47.6
48.2

240
341
460
585
622
655
699
731
779
846
897
945

3.2
6.4

284
431
564
692
734
779
835

1 1 .0

8 .1

12.7
15.9
2 0 .1

2 .6

153

4.8
6.3
9.6

202

304
374
488
735
860
1,046
1,186
1,275
1,314
37
66

79
126
149
192
283
346
425
490
533
531

1 1 .8

15.'5
23.4
27.5
33.6
38.3
41.4
42.7
2.7
4.9
5.9
9.4
1 1 .2

14.5
21.5
26.4
32.4
37.4
40.8
40.7

866

369
554

Per cent
9.1
13.9
17.8
2 1 .8

23.8
25.7
28.5
30.1
32.1
34.0
36.0
37.8
8.7
1 2 .6

17.2
2 2 .2

23.8
25.2
27.2
28.7
30.8
33.6
35.8
37.9
1 0 .0

15.5
20.5
25.3
27.0
29.0
31.3
32.8
34.0
36.3
38.3
40.3
11.4
17.0
2 2 .0

26.5
28.5
30.3
32.4
33.6
35.6
38.1
40.0
42.4

820
901
970
1,038
1,093
1,131
1,227
1,281
1,337

11.3
17.2
21.5
25.8
28.5
30.7
33.1
34.9
36.3
39.6
41.6
43.5

155
235
320
401
434
455
478
500
531
574
599
628

11.4
17.5
23.9
30.1
32.6
34.4
36.3
38.1
40.5
43.9
45.9
48.2

688

234
G

CAU SAL FACTORS IN

IN F A N T

M O R T A L IT Y

T a b l e 9 9 . — Prevalence o f breast and artificial feeding, by month of
infant’ s life and earnings o f father; infants in eight cities — Continued

eneral

Infants surviving at beginning of each specified month
Month of infant’s life and
earnings of father

Breast fed during
month

Total

Partly breast fed
during month

Number Per cent Number
$1,260 and over:
First...........
Second____
Third_____
Fourth____
Fifth...........
Sixth______
Seventh___
Eighth____
Ninth_____
T e n t h ......
Eleventh...
Twelfth___
No earnings :
First______
Second____
Third_____
Fourth____
Fifth______
Sixth______
Seventh___
Eighth____
Ninth_____
T e n t h ......
Eleventh__
Twelfth____
Not reported:
First...........
Second____
T h ird ..___
F ourth ..__
Fifth______
Sixth______
Seventh___
Eighth.........
Ninth______
Tenth_____
Eleventh___
Twelfth____
1

1,878
1,647
1,485
1,294
1,176
1,074
847
733
585
399
272
209

2 ,2 0 0

2,166
2,158
2,154
2,148
2,145
2,141
2,136
2,132
2,129
2,126
2,123
304
294
293
289
282
275
264
258
255
254
253
251

249
195
163
135
117
106
81

354
350
343
339
336
333
332
330
326
319
318 1
315

290
238
209
185
170
149
115

55
35
22

100

69
50
36
27

85.4
76.0
6 8 .8

60.1
54.7
50.1
39.6
34.3
27.4
18.7
1 2 .8

9.8
81.9
66.3
55.6
46.7
41.5
38.5
30. 7
26.4
2 1 .6

13.8
8.7
6 .8

72
124
165
239
282
337
473
528
618
703
763
771
3
29
45
59
63
70
85
91
98
112
122
121

81.9

6 8 .0

28
40
54
58
70
91
98
115

60. 9
54.6
50.6
44. 7
34.6
30.3
2 1 .2

15. 7
11.3
8 .6

121

127
128

Artificially fed dur
ing month

Per cent Number

3.3
5.7
7.6
1 1 .1

13.1
15.7
2 2 .1

24.7
29.0
33.0
35.9
36.3
1 .0

9.9
15.4
20.4
22.3
25.5
32.2
35.3
38.4
44.1
48.2
48.2
2 .8
8 .0

11.7
15.9
17.3
2 1 .0

27.4
29. 7
35.3
37.9
39.9
40.6

Per cent

249
395
508
621
690
734
821
875
929
1,027
1,091
1,143

11.3
18.2
23. 5
28.8
32.1
34.2
38. 3
41.0
43.6
48.2
51.3
53.8

51
69
85
95

107
109
113

16.8
23.5
29.0
32.9
36.2
36.0
37.1
38.4
40.0
42.1
43.1
45.0

54
84
93
98
106
113
126
132
142
148
155
160

15.3
24.0
27.1
28.9
31. 5
33.9
38.0
40.0
43.6
46.4
48.7
50.8

102

99
98
99
102

Excluding those who died not fed.

eneral

able

100

— Type o f feeding during first nine months o f life, by earn
ings o f father; infants in seven cities
Months lived from birth to end of ninth

Earnings o f father
Total

Months of breast
feeding

Months of partly
breast feeding

Number Per cent Number
Total_________ 180,412.0 102,768.5
Less than $450...........
$450-$549....................
$550-$649.................
$650-$849............ .
$850-$l, 049.......
$1,050-$1,249________
$1,250 and over______
No earnings________
Not reported............
1 Per

25, 036. 5
23, 511. 0
24, 328. 0
42, 250. 0
28, 481. 0
11,946. 5
19,344. 5
2,489. 0
3,025. 5

14,196. 5
13, 451. 5
13, 871. 5
24, 413. 5
16, 697. 5
6,750.0
10,703. 5
. 1,164. 0
1, 520. 5

57.0

31,412.0

56. 7
57.2
57.0
57.8
58.6
56. 5
55.3
46.8
50.3

5,291. 5
5.012.0
4,445. 0
6.788.0
4.240.0
1.701.0
2,834. 5
539.0
561.0

Per cent Number

Type of
feeding
not
reported
Per cent (number) i

17.4

46,149. 5

25.6

82.0

2 1 .1

5.520.0
5,047. 5
6 . 0 1 1 .0
11,028. 5
7, 518. 5
3,495. 5
5,806.0
784.0
938. 5

2 2 .0

28.5

21.3
18.3
16.1
14.9
14.2
14.7
21. 7
18.5

cent not shown for “ not reported ” group because not significant.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Months of artifi
cial feeding

21. 5
24. 7
26.1
26.4
29.3
30.0
31. 5
31.0

.5
2 0 .0

25.0

.5
2 .0

5.5

235

APPENDIX 1>.— GENERAL TABLES

G e n e r a l T a b l e 101 .— Monthly death rates, by type o f feeding, earnings o f father,

and month o f life; infants in seven cities
Monthly death rates:1 Earnings of father
Month of life and type of
feeding

Less
than
$450

First month_____________ .
Breast fed_________ ___
Partly breast fed. _____
Artificially f e d . . . ______
Second month........................
Breast fed_____ ________
Partly breast fed .........
Third month I_____________
Breast fed_____________
Partly breast fed _____
Artificially fed.......... v - Fourth month__________ . . .
Artificially fed.................
Fifth month..........................
Partly breast fed. _____
Artificially fed.................
Sixth month_______________
Breast fed_____________
Artificially fed.................
Seventh month____________
Artificially fed..............
Eighth month........................
Breast fed_____ ________
Partly breast f e d ......... .
Artificially fed_________
Ninth month........ ...............
Partly breast fed_______
Artificially fed.................
Tenth month_________ ____
Artificially fed....... .........
Eleventh month___________
Artificially fed.................
Twelfth month......................
Artificially fed_________

$450$549

55.8
22.5
27.8
98.9
15.1
10.4
14.9
41.9
13.6
6.9
25. 2
33.3
15.2
5.7
13.4
43.8
12.9
5.1
10.8
33. 1
11.3
4.4
10.5
25.5
12.1
2.9
8.9
28.4
10.0
1.2
7.0
22.3
9.4
5.8
2.7
21.1
11.0
13.0
4.2
19.0
8.1
4.7
7.3
10.6
5.8
10.9
3.2
7.2

1 Not shown where base is less than 25.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

$550$649

46.0
15.3
38.8
87.5
10.4
6.0
15.1
35.2
11.2
5.7
18.1
30.4
8.3
4.3
7.2
20.5
5.7
2.7
1.9
16.1
12.7
1.5
6.3
41.2
9.3
2.0
5.9
24.3
4.7
2.3
3.1
9.6
4.7
1.5
1.9
11.6
6.7
1.9
2.6
15.4
4.8

43.3
17.0
32.6
52.8
10.8
5.1
33.5
30.2
6.5
2.0
17.9
17.7
7.3
2.4
8.7
18.8
8.8
3.2
11.6
19.1
7.4
1.5
7.4
18.0
9.7
1.9
5.2
24.0
9.1
6.6
2.3
18.5
7.3
1.4
1.0
19.1
5.0
1.8
3.6
8.5
3.1

3.4
8.9
8.0
11.5
4.2
11.6

.8
7.1
4.3
5.1
4.8

$650$849

46.5
20.1
52.2
41.1
8.9
5.3
8.4
25.7
8.4
3.6
8.8
23.8
7.4
2.7
3.9
20.0
9.4
4.0
4.7
22.4
4.9
2.5
3.8
9.9
4.1
1.0
.9
10.7
4.1
1.8
3.6
7.1
5.7
2.9
3.8
9.8
4.2
49
1.7
6.3
3.5
3.8
1.0
6.1
5.3
4.8
2.5
8.3

$850- $1,050- $1,250
and
$1,049 $1,249 over

No
earn
ings

Not re
ported

38.2
11.2
41.7
36.1
3.7
2.4
8.1
7.6
1.9
2.0

60.7
16.1

41.1
10.3

98.0
3.4
5.1

18.5
20.0
12.6
71.4
23.8
11.7

38.0
11.4
11.6
40.7
6.5
2.4
13.1
23.5
5.0
2.2
5.0
14 5
5.0
2.9
6.6
9.8
3.2
.5
2.7
8.9
6.0
1.2
6.1
14 4
2.2
.7
5.8
3.8
1.7
9.1
5.5
4.3
5.7
6.2
6.1
3.4
12.2
1.9
4.7
2.3
2.4
.8
3.7

33.1
7.7
51.6
3.0
2.9
43
5.2
1.1
25.3
12.5
3.0
2.5
5.0
4.5
40
6.9
6.8
3.0
5.2
13.2
2.3
3.6
3.5

2.0
2.8
42
8.1
1.4
4.3
1.9
.9
41
2.3

¡3.7
6.1
35.3
242
14 8
67.8
10.5
24.8
68.6
40.0
9.4
14.3
90.9
22.7
12.3
11.8
40.8
11.6

4.2
3:7
1.9
2.7

40
.8

2.3
L4

11.0
20.2
3.9

1.9
3.1
4.1
2.0
3.5
.8

3.2
1.4

9.8
3.9

2.9
1.4

9.3
7.9

1.7
1.5

2.7
1.9

18.3
15.9

3.5

8.3
26.5

3.2

43.0
8.8
5.4
20.4
8.9
_____: :
18.9
3.0
8.8
6.0
15.9
12.1
10.2
22.7
21.5
29.0
26.1
141
3.1
6.8
9.4
27.8
15.7
3.2
6.2

236

CAU SAL FACTORS IN

I N F A N T M O R T A L IT Y

G e n e r a l T a b l e 102 .— Infant mortality rates, by earnings o f father and color and

nativity o f mother; live births in seven cities

Births to all mothers
Earnings of
father

Births to native
white mothers

Births to foreignborn white mothers

Births to colored
mothers

Infant
Infant
Infant
Infant
Live Infant mor Live Infant mor Live Infant mor Live Infant mor
tality
deaths
tality
births
deaths
births
deaths
tality
births
deaths
tality
births
rates1
rates1
rates1
rates1
2,368

Total_____ 21,536
3,085
2,827
2,908
5,050
3,345
1,391
2,252
313
365
Not reported.......

Less than $450___
$450-$549....... ......
$550-$649............ $650-$849......... .
04Q
$1 050-$1 249
$1,250 and over...

110.0 11,323

515 166.9
653
355 125. 6
926
339 116.6 1,390
543 107.5 2,914
82. 8 2, 291
277
64. 0 1^070
89
133
59.1 L770
128
66 210. 9
181
51 139.7

1,063

93.9 8,762

111 170.0 1,885
112 121.0 1,504
154 110.8 1,347
290 99.5 1,990
175 76.4 1,012
62. 6 '307
67
467
102
57.6
111
24 187.5
28 154.7
139

1,084

123.7 1,451

221

152.3

547
397
171
146
42
14
15
74
45

89
65
21
15
6
1
3
16
5

162.7
163.7
122.8
102.7

315 167.1
178 118.4
164 121.8
238 119.6
96 94.9
68.4
21
28
60.0
26 234.2
18 .129.5

i Not shown where base is less than 100.
G e n e r a l T a b l e 103 .— Proportion o f confinements with instrumental delivery, by

earnings o f father; confinements in Baltimore

Earnings of father

Total.............

Total
confine
ments 1

11,463

No earnings............
Less than $450____
$450-$649__..............
$650-$849.................

232
1,668
3,117
2,546

Confinements with
instrumental de
livery
Number

Per cent

a 866

7r6

10
72
176
182

4.3
4.3
5.6
7.1

Earnings of father

Total
confine
ments 1

Number Per cent
$850-$1.049..............
$1,050-$1,249............
$1,250-$1,449............
$1,450 and over____
Not reported..........

1,675
696
444
846
239

1 Including confinements resulting in miscarriages of less than 7 months’ gestation.
a Confinements resulting in plural births counted but once.

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

ConfinenLents with
instruntentai delivery

160
70
47
120
29

9.6
10.1
10.6
14.2
12.1

A P PE N D IX E .— CH ARTS
C hart I.—D eaths from respiratory and from gastric and intestinal diseases, by month of death
Number of
deaths

Jan.

Feb.

Mar.

.Apr.

M ay

June

July

Aug.

Sept.

Oct.

Nov.

-------- Gastric and intestinal diseases
.........Respiratory diseases

237

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Dec.

238

C A U S A L -F A C T O R S

_
,„
Monthly
death
rate

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

IN F A N T

M O R T A L IT Y

Chart II.—M onthly death rates, by month of life

239

A P P E N D IX E .— C H A R T S

Infant
mortality
rate

C hart III.—I nfant mortality rates , by age of mother

---

15 yrs.

20 yrs.

25 yrs.

Age

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

45 yrs
Rate based on less than 100 cases

CAU SAL FACTORS IN

I N F A N T M O R T A L IT Y

Chart I V — I nfant mortality rates, by order of birth

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

241

A P P E N D I X E .-----C H A R T S

Infant
mortality
rate
18 0-

C hart V.—I nfant mortality rates, by interval since preceding birth

1 yr.
Interval

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

2 yrs.

3 yrs.

4 yrs.

242

C A U SA L FACTO RS IN

IN F A N T

M O R T A L IT Y

Chart VI.—I nfant mortality rates for single and plural, premature and full-time births
Infant
mortality
rate
700 —

530.9

[

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

,
J

Single
Premature

243

A P P E N D I X E .— C H A R T S

C hart VII.—R elative mortality, by

OF FEEDING

Artificially fed

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

244

CAU SAL FACTO RS IN

IN F A N T

M O R T A L IT Y

Chart VIII.—Infant mortality rates, by color and nationality of mother
Infant
mortality

ratej

220 —

200.3

Native Foreign Italian
white
white

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

Jewish

French German
Canadian

Polish

Portu- Allother Colored
gese
foreign

245

A P P E N D IX E .-----C H A R T S

Chabt IX .—I nfant mortality rates, by color and nativity of mothers and earnings of father
Infant
mortality
rate

160 i v — I ____
V

\
\
\

\
\

140

\
A

120

.............

\
%\
i

\
V - _ .

■

S ^ N

N
V

'V
%
%

100
\ \
\

%
%

%
>

n *

Under
$460
Earnings
of father

$460
to

$660
to
$649

$650
to
$849

$850
to
$1,049
All mothers
Native white
Foreign-horn white
Colored

96515°— 251------ 17

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis

$1,050
to
$1,249

$1,250
and
over

https://fraser.stlouisfed.org
Federal Reserve Bank of St. Louis