OF

NATIONAL CENTER Series 21 

For HEALTH STATISTICS INumber. II 

VITAL and HEALTH STATISTICS 

DATA FROM THE NATIONAL VITAL STATISTICS 

Natality


Statistics


Analysis


United States -1964 

An analytical study of recent fertility 

of period and cohort measures. Discusses 

fertility of maior population groups by 

of residence, including Puerio Rico 

SYSTEM 

FYwFm’w T!&“

t 

PUBLICATIO!JS %ANC:-

133mfw iJwiARY 

trends in terms 

variations in 

race and place 

and the Virgin 

Islands. Also a discussion of characteristics of live 

births including birth weight, period of gestation, 

attendant at birth, month of birth, plurality, sex, and 

legitimacy. 

Washington, D.C. February 1967 

U.S. DEPARTMENT OF 

HEALTH, EDUCATION, AND WELFARE Public Health Service 

John W. Gardner Wi i iiam H. Stewart 

Secretary Surgeon Genera I 
Public Health Service Publication No. 1000-Series 21-No. 11 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C., 20402- Price 35 cents 
NATIONAL CENTER FOR HEALTH STATISTICS 

FORREST E. LINDER, PH. D., Director 

THEODORE D. WOOLSEY, Deputy Director 

OSWALD K. SAGEN, PH. D., Assistant Director 

WALT R. SIMMONS, M. A., Statistical Advisor 

ALICE M. WATERHOUSE, M. D., Medical Consultant 

JAMES E. KELLY, D, D. S., Derztaz Advisor 

LOUIS R. STOLCIS, M.A., Executive O//icey 

DONALD GREEN, In/orm.atian O//icer 

DIV[S1ON OF VITAL STATISTICS 

ROBERT D. GROVE, PH.D., CAie/ 

ANDERS S. LUND E, PH.D., Assistant Chic/ 

ROBERT A. ISRAEL, M. S., Cbie/, MOditY Statistics Branch 

ARTHUR A. CAMPBELL, Chiej, Natality Statistics Branch 

CHARLES R. COUNCIL, Cbie/, Registration Methods Branch 

ARTHUR A. CAMPBELL, Acting Chief, Marriage and Divorce Statistics Branch 

Public Health Service Publication No. 1000-Series 21-No. 11 

Library of Congress Catalog Card Number 65-62786 
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CONTENTS 

Inmoduction 

Recent Trends in FertiEW 

Cohort Fertility Rates---------------------=------------------------

Period Fertili~Rates 

Timing of Birtis 

Fertility at Younger Ages -------------------------------------------

Influence of Contraceptive Pills 

The Childbearing Population 

The Fertility ofMajor Population Groups 

Fertility by Color 

Fertility by States and Geographic Areas 

Fertility by Memopolitan Residence 

/ 

Characteristics ofBirtis 

Sex Ratio 

Plural Birtis------------------.-----------------------------------= 

Attendant at Birtiand Place of DeHvery 

Birth Weight and Period of Gestation 

Season of Birti 

Illegi~acy 

Births in Puerto Rico and the Virgin Islands (U.S.)------------------------

Rates of Birtiand Namral Increase 

Season of Birti 

Illegitimate Births 

References 

Page 

1


1 

3 

3 

6 

7 

10


10


11 

11 

13 

20


22


22


2-4


24


25


30


31


33


33


34


35


38


III 
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CONTENTS—Con. 

Figure Page 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

Cumulative birth rates by exact age--------------------------------

Total fertili~rates 

Birth rates by age of mother 

Percentage of women with specified number of births byexactage30 

on January l---------------------------------------------------

Cumulative birth rates by exact ages 18-24 years 

Fertility rates by color 

Birth rates by State, l964----------------------------------------

Percent changein birth rates by State, 1960-64----------------------

Illegitimate births per 1,000 unmarried women, byageMonthly indexes oflive births: PuertoRicoandthe United States, 1964--

Illegitimacy ratios: Puerto Rico and the Virgin Islands 

4


5


7 “:’


9 “


10


12 ,


15


19


32


35


36


IV 
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CONTENTS—Con. 

Table 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

13. 

14. 

15. 

16. 

17’. 

18. 

19. 

20. 

21. 

Live births, birth rates, and fertility rates: United States, 1909 -65----

Total fertility rates: United States, 1917 -65------------------= 

Birth rates by age of mother: United States, 1940-64 

Birth rates adjusted and not adjusted for underregistration and percent 

ch~ge, by color and age of mother: United States, 1940, 1959, and 

1964 ----------------------------------------------------------

Measures of fertility bygeographic region United States, 1964-------

Birth rates and percent change: United States, each geographic division 

and State, l96Omdl964----------------------------------------

Index of birth rates by geographic division: United States, 1960and 

l964----------------------------------------------------------

Birth rates for standard metropolitan statistical areas and percent 

change: United States, 1960 and 1964-, 

Live births by sex and sex ratio at birth, by color andplurality: 

United States, l964---------------------------------------------

Sex ratio at birth, by live-birth order, race, and age ofmother: United 

States, l964---------------------------------------------------

Number of live births in plural deliveries and ratio of-plural live 

births to total live births: United States, 1944, 1950, and 1956-64----

Ratio of plural live births to total live births, bycolorand age of 

mother: United States, 1964-------------------------------------

Percentage distribution of live births, byplaceof delivery and attendant: 

United States and each State, 1964 

Median birth weight in single and plural deliveries, bycolor and sex: 

United States, l964---------------------------------------------

Median birth weight, by live-birth order, color, and age of mother: 

United States, l964---------------------------------------------

Median birth weight, by color and period of gestation: Baltimore, 

California, District of Columbia, and New York Citycombined, 1964--

MonthIy index of live births: United States, 1935 -64------------------

Seasonal factors and seasonally adjusted birth rates and fertili~ rates, 

by month of occurrence: .United States, 1964-----------------------

Estimated number of illegitimate live births and ratios, bycolorsnd 

age of mother: United States, 1964 

Rates of birth and natural increase: Puerto Rico, Virgin Islands, and 

United States, l94O-64------------------------------------------

Percentage distribution of births by marital status of parents, 1964, 

and amount of change in distribution, 1962-64, by age of mother: 

Puerto Rico ---------------------------------------------------

Page 

2 

6 

8 

14 

16 

17 

20 

21 

22 

23 

24 

24 

26 

27 

28 

29 

30 

31 -

33 

34 

37 

.V 
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NATALITY RATES AND RATIOS, 1964 

TOTAL NUMBER OF LIVE BIRTHS-4,027 ,490 

CRUDE BIRTH RATE . . . . . . . . . . . . . . . . . . . ...21.0 

(per 1,000 population) 

CRUDE RATE OF NATURAL INCREASE . . . . . 11.6 

(per 1,000 population) 

INTRINSIC RATE OF NATURAL INCREASE . . 15.6 

(per 1,000 women) 

GROSS REPRODUCTION RATE. . . . . . . . . . . ...1.564 

NET REPRODUCTION RATE. . . . . . . . . . . . . . . 1,507 

TOTAL FERTILITY RATE .,. . . . . . . . . . . . . 3,201.8 

GENERAL FERTILITY RATE . . . . . . . . . . . . . . 104.8 

(per 1,000 women 15-44 years) 

CUMULATIVE BIRTH RATE BY AGE OF 

WOMEN, JANUARY 1,1965 

(per 1,000 women) 

15-19 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...86 

20-24 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888 

25-29 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,121 

30-34 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,817 

35-39 years . . . . . . . . . . . . . . . . . . . . . . . . . . ...2.931 

40-44 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,831 

45-49 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,S52 

50-54 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,316 

1 

PREMATURE BIRTHS (under 37 weeks’ gestation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.9 

(per 100 live births) 

IMMATURE BIRTHS (2,500 grams or less) . . . . 8.2 

(per 100 live births) 

MEDIAN WEIGHT AT BIRTH . . . . . . . . . . . . . . . 3,290 

(in grams) 

HOSPITAL DELIVERIES . . . . . . . . . . . . . . . . . . . . 97.5 

(per 100 live births) 

PLURAL BIRTHS . . . . . . . . . . . . . . . . . . . . . . . . . . 19.9 

(per 1,000 live births) 

SEX RATIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,047 

(males per 1,000 female live births) 

ESTIMATED LEGITIMATE FERTILITY 

RATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140.9 

(per 1,000 married women 15-44 years) 

ESTIMATED ILLEGITIMATE FERTILITY 

RATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.4 

(per 1,000 unmarried women 15-44 years) 

ESTIMATED PERCENT COMPLETENESS 

OF BIRTH REGISTRATION . . . . . . . . . . . . . . . . 98.9 

SYMBOLS 

Data not available 

Category not applicable . . . 

I Quantity zero -I 

Quantity more than Obutless than O.05----- 0.0 

Figure does not meet standards of 

~ 

VI

NOTES TO TABLES 

~.	 A~~ska ad Hawaii. —All tables showing time series include data 

for Alaska beginning 1959 and for Hawaii beginning 1960. 

2.	 50-percent sample.— All data for the years 1951-54 and 1956-65 are 

derived from 50-percent samples of birth records. Statistics for 

these years were obtained by multiplying the sample figures by 2. 

3.	 Not stated data.- For 1964, births with age of mother and color not 

stated were allocated during data processing on the basis of characteristics of births that were similar to the not stated cases in other 

respects. Before 1963, color not stated was assigned as white. For 

other characteristics, not stated information was distributed in 

proportion to the known information unless otherwise noted in the 

particular table. 

4.	 Ad@stment forwz.derve~”stvation of births.—.Adjustment for failure to 

register births was discontinued in 1960, when”it was estimated that 

98.9 percent of all births were registered. However, cohort rates 

in table 2 make allowances for both the underregistration of births 

and the underenumeration of the base population. 

5.	 Popzdation bases. —Except as noted, birth rates shown in this report 

are based on populations present in the respective areas. The populations for the United States exclude the Armed Forces overseas and 

persons living abroad but include the Armed Forces stationed in 

each area. Rates for 1940, 1950, and 1960 are based on the population enumerated as of April 1 and estimated as of July 1 for all 

other years. 
THIS REPORT pvesents m“ intevpvets important features of statistics 

for births in the United States in 1964 which aye based on information obtained from microfilm copies of the original certificates of live bivth. 

The year 1964 was the llth consecutive year in which the number of 

bivths exceeded fouv million. The bivth rate conti~ed its decline from 

a peak in 1957. 

This decline was dwe in pavt to the shifl toward younger ages of childbearing that occuvred in the 1950 ?s. The same wotn.en who had relatively high biyth Yates at younger ages in the 1950’P compensated with 

relatively lower birth rates at ages eve?’ 25 in the 1960 ‘s. Declines in 

fertility at the younger childbearing ages (undev 25 years) may be due 

to the postponement of marriage and childbearing to later ages w to a 

reduction in the number of children couples will have. 

Othey findings of the vepovt include: 

Women who had completed the childbearing peviod by the end of 1964 

(those 50 years of age) had an average of 2.3 children. Younger women 

will exceed this figure by a wide mav~”n. By the end of 1964, women 

aged 30 had already bovne 2.7 children. 

There is a potential for a vise in the annual number of bi?%hs in the 

near future due to the increasing size of the young chtldbeaving po@dation. In 1965 there were about 6.8 million women in the age group 20-24 

yeans. By 1970 there will be approximately 8.6 million, an incvease of 

26 percent. 

Differences in fertility between white and nonwhite women have been 

faivly constant in ~ecent years. Both g?wups reached peak fevtility in 

1957 and since then have shown declines in theiv bivth rates. 

Declines in the biyth rate occurred in every State between 1960 and 1964. 

Over 97 percent of all live births in the entive United States were deliveved in hospitals or clinics. The pvopovtions were 99 pevcent for 

white bivths and 89 peycent foy nonwhite biyths. In seveyal of the Southeyn States ovey 20 peycent of the nonwhite biyths weye not attended by 

doctoys. 

About 8 out of eveyy 100 births were classified as immatwve, that is, 

weighing less than 2,501 warns (5 pounds, 9 mnces). The median birth 

weight for all live binths was 3,290 grams (7 pounds, 4 ounces). 

An estimated 7 percent of all bivths weye illegitimate in 1964. 

VIII 
NATALITY STATISTICS ANALYSIS, 1964


Arthur A, Campbell, Alice Clague, and Frank Godley, Division of Vital Statistics 

INTRODUCTION 

The purpose of this report is to present and 

interpret important features of 1964 birth statistics for the United States. These statistics are 

shown in detail in Volume I of vital Statistics of 

the United States, 1964.1 

Birth statistics for 1964 are based on information reported on the birth certificates of 54 

reporting areas in the United States and of 

Puerto Rico and the Virgin Islands. Registrars 

in these areas send copies of all birth certificates to the Division of Vital Statistics, where a 

50-percent sample of the certificates is selected. 

AU tabulations are based on this sample. 

Most of the statistics presented here do not 

include an adjustment for the faiIure to register 

some births. This adjustment was discontinued 

in 1960, when it was estimated that 98.9 percent 

of all births were, registered. However, the cohort fertility rates which are cited in the description of recent trends in fertility make allowances 

for both the underregistration of births and the 

underenumeration of the base population. 

Additional details concerning technical aspects of birth statistics may be found in the 

Technical Appendix of Volume I of Vital Statistics 

of the United States, 1964.1 

RECENT TRENDS IN FERTILITY 

The year 1964 was the llth consecutive year 

in which over four million children were born in 

the United States. As the various time series in 

table 1 show, the downturn in fertility which began in the late 1950’s continued through 1964. In 

that year, 4,027,490 children were born, the birth 

rate was 21.0 births per 1,000 population, and 

the fertility rate was 104.8 births per 1,000 

women 15-44 years of age. 

Although the recent declines in the fertility 

rate have been fairly rapid (averaging about 4 

percent per year between 1961 and 1964) the 

1964 rate of 104.8 is still well above the levels’ 

of 76 to 79 observed in the period 1933-39. Even 

the provisional 1965 fertility rate of 96.7 is high . 

in relation to the depressed fertility rates of the 

1930’s. 

In spite of relatively high fertility rates, however, the birth rate per 1,000 total population is 

now approaching the low values observed in the 

1930’s, as comparisons of figures in table 1 indicate. In the pericd 1933-39; the number of births 

per 1,000 population varied between 18 and 19. 

In comparison, the 1964 rate was 21.0, and the 

provisional rate for 1965 is 19.4. 

Recent birth rates are so much closer to prewar levels than are recent fertility rates because 

the childbearing population (assumed to consist 

of women 15-44 years of age) is a smaller proportiori of the totaI population than it was’ before 

the war. In the middIe of the 1933-39 period 

(1936), the childbearing 

percent of the total 

comparable proportion 

sult of the decline in 

stantially higher fertility 

large enough to maintain 

population constituted 24 

population; in 1964, the 

was 20 percent. As a rethis proportion, the subof today’s women is only 

the birthrate of the total 

population at a level close to the low rates of the 

1930’s. If the ratio of the birthrate to the fertiliq 

243-645 0 -67-2 1 
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Table 1. Live births,birth rates, and fertilityrates: United States,1909-65


[Notesb tables given
 onpageVII]


Live Fertility Year births ratel 

Rate per Rate per


Registeredbirths Number 1,000 1,000women
 population aged 15-44 years


l9652-------------------------------------------------------------
 3,767,000 19.4 96.7


4,027,490 21.0 104.8 

1963 .........--------- 4,098,020 21.7 108.4 

1962 ........------ 4,167,362 22.4 112.1 

1961 ........- 4,268,326 23.3 117.2 

1960 -.......------ .-------- 4,257,850 23.7 118.0 

l959--------------------------------------------------------------

l964--------------------------------------------------------------


4,244,796 24.o 118.8


B.irthsadjusted for underregistrationa


l959--------------------------------------------------------------
 4,295,000 24.3 120.2


l958--------------------------------------------------------------
 4,255,000 24.5 120.2


l957--------------------------------------------------------------
 4,308,000 25.3 122.9


1956 4,218,000 25.2 121.2


l955--------------------------------------------------------------
 4,104,000 25.0 118.5


l954--------------------------------------------------------------
 4,078,000 25,3 118.1


1953 - 3,965,000 25.1 115.2


l952--------------------------------------------------------------
 3,913,000 25.1 113.9


1951 3,823,000 24.9 111.5


1950 --..- 3,632,000 24.1 106.2


l949--------------------------------------------------------------
 3,649,000 24.5 107.1


1948 .----------- 3,637,000 24.9 107.3


1947 3,817,000 26.6 113.3


1946 3,411,000 24.1 101.9


1945 :---------------- 2,858,000 20.4 85.9
 ::~:--------------------------------------------------------------
 2,939,000 21.2 88.8 

3,104,000 22.7 94.3 

1942 2,989,000 22.2 91.5 

1941 2,703,000 20.3 83.4 

1940 2,559,000 19.4 79.9 

l939--------------------------------------------------------------
 2,466,000 18.8 77.6


1938 2,496,000 19.2 79.1


L937--------------------------------------------------------------
 2,413,000 18.7 77.I.

1936.........--------- .-------- 2,355,000 18.4 75.8


1935 ........-------.----------.-
--.-.-- 2,377,000 18.7 77.2


l934--------------------------------------------------------------
 2,396,000 19.0 78.5


1933 2,307,000 18.4 76.3


1932 2,440,000 19.5 81.7


1931 2,506,000 20.2 84.6


1930 2,618,000 21.3 89.2


l929--------------------------------------------------------------
 2,582,000 21.2 89.3


1928........- .........--------- 2,674,000 22.2 93.8


l927--------------------------------------------------------------

1926 2,839,000 24.2 102.6 

1925 .........---------- .-------- 2,909,000 25.1 106.6 

2,979,000 26.1 110.9 

2,802,000 23.5 99.8


l924--------------------------------------------------------------


1923 2,910,000 26.C 110.5


1922 - 2,882,00C 26.2 111.2


1921 3,055,00C 28.1 119.8


1920 2,950,00C 27.7 117.9


.1919 ----.------- 2,740,Ooc 26.1 111.2


1918 2,948,00C 28.1 119.8


l9l7--------------------------------------------------------------

1916 .--------- 2,964,00C 29.1 123.4 

1915 -. 2,965,00C :;;: ------. 2,966,00C 

29.: 

29.5 

125.0 

126.6 

2,869,00C 29.: 124.7 

i912 ------.--- - 2,840,OOC 

1911 2,809,00C 

29.$ 29.5 

125.8 

126.3 

1910 2,777,00C 30.1 126.8 

2,718,OOC 30.( 126.8 

2,944,Ooc 28.? 121.0


l9o9--------------------------------------------------------------


lFor 1917-lg and lg41-46,based cm populationincludingArmed Forces abroad.


2provisi0nal estimates.


3F0r Ig15-32,figures include adjustments for Statesnot in the registration area. For years prior to 

1915; estimatesare based on the number of births registeredin the 10 originalregistrationStates. Estimates for 1909-34were preparedby P. K.Whelpton. See NationalOffice of VitalStatistics,“Birthsand Birth 

Rates in the Entire United States, 1909 to 1948,” Vital Statistics—SpecialReports,Vol. 33, No. 8, 1950. 

2

rate had remained unchanged since 1933-39, the 

birth rate in 1964 would have been 25.3 rather 

than only 21.0. 

The factors associated with the long-term 

rise and subsequent decline in fertiliWarediscussed in detail in NataWy Statistics Analysis, 

1963.~ Inasmuch as fertility data for1964 were 

consistent with that interpretation of recent 

trends, the analysis will not be repeated in this 

report. However, a summary of the interpretation is presented in the following paragraphs. 

Readers wishing more detail may refer to the 

earlier report. 

Cohort Fertiiity Rates 

An adequate description of trends infertility 

requires the use of cohort fertility rates. These 

rates are designed to follow thefertilityofgroups 

of women as they proceed through the childbearing years of life. The groups to which these 

rates relate are called “cohorts” and are identified by the year of birth of the women included in 

them. (The birth years by which cohorts are 

identified end on June 30. The cohort of 1920, for 

example, was born in the 12 months preceding 

June 30, 1920. This convention has been adopted 

for technical reasons stqted on pages 106-108 of 

reference 3.) Thus these women always carry the 

same designation, regardless of their ages. This 

feature facilitates comparisons over periods of 

time. For example, statements can be made about 

the fertili~ of the 1920 cohort when its members 

were 30 years of age in 1950 and when they were 

40 years of age in 1960. The same group of women 

is referred to in both years. 

One of the most commonly used cohort measures is the “cumulative fertility rate. ” This is the 

average number of children ever born in a cohort 

up to an exact age. For example, the cumulative 

fertility rate of 377 for the 1930 cohort by exact 

age 20 (assumed to have been attained on January 

1, 1950) means that by the time the women of this 

cohort reached their 20th birthday they had borne 

377 children per 1,000 women. 

Series of cumulative fertility rates make it 

possible to see trends in the average number of 

children ever born by different ages in the reproductive period. Such series are presented in figure 1. They show the long-term decline in cumulative rates, which ended with the low rates of the 

1909 cohort, and the subsequent rise, which appears to be ending with the cohorts of the 1930’s. 

Of particular interest is the mend in the cumulative fertility rate by age 50, often called the 

“completed fertility rate. ” Figure 1 shows the 

long-term decline in completed fertility from 

3,818 births per 1,000 women for the 1875 cohort 

to 2,230 for the cohort of 1909. It is difficult to 

predict how high completed fertility will be for 

some of the cohorts still in the reproductive years 

of life, but projections based on women’s expectations of their future childbearing indicate that the 

cohorts of 1931-35 will complete their families 

with 3,100 to 3,500 births per 1,000 women. It now 

seems probable that the cohorts of 1940 and later 

years will show some reductions in completed fertility. (See Natality Statistics Analysis, 1963,2 for 

a discussion of the evidence concerning future 

trends in completed fertility.) 

Period Fertility Rates 

To a major degree, the postwar rise in fertility rates was a consequence of the trend toward 

larger families (that is, higher completed fertility). But this is not the whole story, for “period 

fertility rates” (that is, fertility measures relating to births occurring in particular calendar 

years as contrasted with cohort rates) were also 

influenced by the inflationary y effects of certain 

changes in the timing. of births. The extent to 

which annual measures of fertility were inflated 

in the postwar period can best be appreciated by 

an inspection of the trend in the “total fertility 

rate, ” shown in figure 2 and table 2. 

The total fertility rate is the sum of agespecific birth rates for single years of age observed in a single calendar year. An important 

conceptual advantage of the total fertility rate 

is that it states the number of births 1,000 women 

would have if they experienced a given set of agespecific birth rates throughout the reproductive 

age span. The rate of 3,197 for 1964, for example, means that if 1,000 women were to have the 

same birth rate at each single year of age that 

was observed in 1964 they would have a total of 

3,197 children by the time they reached the end 

of the reproductive period (assumed to be 50 

years of age). 

3 
4,000 

3$00 

3J300 

: 

z 

~ 

0 

:. 2,000 

E 

w

L 

u 

s 

a 

1$00 

1,000 

500 

20 

0 

1875 1880 1885 1890 1895 I900 1905 1910 1915 1920 1925 1930 1935 1940 1945 

COHORT 

Figure 1. Cumulative birth rates by exact age. 

(Rates based on births adjusted for underregi strati on for al 1 years, including 1960-61+,and on population 

estimates adjusted for underenumeration) 

4 
Rote per 1,000 women 

4,000 

3,500 

8 

> 3,000 (provisional)’ 

2,500 

2,000 

0 [ 1111 1111111 II I Ill II 11111111111111111 1-- 1917 I920 1925 1930 1935 1940 1945 I950 1955 1960 

YEAR 

Figure 2. Total fertility rates. 

(Rates based on births adjusted for underregistration 

lation estimates adjusted 

This feature makes it possible to compare 

the total fertility rate with the completed fertility 

rate. Such comparisons give some idea of theextent to which fertility in a given year may be distorted by factors thatcanhave onlya temporary 

effect. For example, the total fertility rate for 

1957 was 3,724. This was the highest rate observed in this country since the beginning of the 

series in 1917. However, therewas evidencefrom 

a 1955 interview survey of married women that 

no actual group ofwomen then in thechildbearing 

population expected to have as many as 3,700 

children per l,OOOwomen bytheendofthe reproductiveperiod.(See projected cumulative fertility 

rates for ages 45-49 in table 10-7 onpages 356 

and 3570freference 4.)This meant that the 1957 

for all years, including 1960-6V, and on popufor underenumeration)


rate of3,724 was “inflated’’i nthesensetbat such 

a high rate could not be maintained for a long time. 

The total fertility rate would soon have to descend 

to a level more compatible with the experience of. 

actual groups of women living through the childbearing period. 

The recent decline of the total fertility rate to 

values close to 3,000 represents in part an inevitable decline from the inflated levels of 3,500-

3,700 observed throughout the period between 

1954 and 1962. The total fertility rate had been 

distorted upward for at least 9 years and could 

no longer remain at such high levels because of 

the average coupIe’s desire for families of moderate size. 

5’ 

1965 
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-------- ---------- --------------------------

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Table 2. Total fertility rates: United States, 1917.65 

[Notes totablesgiven cm page VII] 

Rate


Year per 1,000
 women


Rate


Year per 1,000
 women


1965---------------------------


1964---------------------------


1963--------- ------.-


1962---------------------------


1961


1960---------------------------


1959---------------------------


1958


1957 ---.---


1956


1955---------------------------


1954---------------------------


1953---------------------------


1952 -.------


1951--------


1950---------------------------


1949---------------------------


1948---------------------------


1947


1946


1945 -----”--


1944


1943---------------------------


1942---------------------------


1941---------------------------


Iprovisionalestimate.


12,950


3,197


3,331


3,476


3,620


3,655


3,669


3,6.54


3,724


3,634


3,521


3,501


3,378


3,307


3,209


3,030


3,030


3,013


3,158


2,829


2,392


2,466


2,616


2,532


2,314


1940-------- --.---.,-


1939--------


1938--------------------------


1937--------------------------


1936--------------------------


1935


1934


1933--------------------------


1932 --”-----


1931


1930 ........--


1929--------------------------


1928--------------------------


1927--------------------------


1926--------


1925--------------------------


1924


1923--------------------------


1922--------------------------


1921 .-


1920--------------------------


1919 .-


1918--------


1917


2>214


2,154


2,200


2,147


2,119


2,163


2,205


2,149


2,288


2,376


2,509


2,524


2.656


2;826


2,910


3,027


3,144


3,116


3,125


3,349


3,273


3,078


3,313


3,332


NOTE: The total fertility rate is the sum of age-specific birth rates for single 

years of age for women 14-49 years of age. The birth rates for single years of age 

used to compute total fertility rates are based on births adjusted for underregistra­


tion for all years (including 1960-65) and on population estimates adjusted for under­


enumeration.Hence, they are not precisely comparable to the birth rates andfertility


rates shown in table 1. For method of adjusting the population bases, see the Meth­


odological Appendix in National Office of Vital Statistics, “FertilityTables for


Birth Cohorts of American Women,” by P. K. Whelpton and A. A. Campbell, Vital Statis­


tics—Special Reports, Vol. 51, No. 1, 1960.


Timing of Births 

The temporaryinflation ofthetotal
fertility


ratein thepostwarperiodwas broughtaboutby


two overlappingshiftsin thetimingof births.


First,thecohortsof1916-25(approximately) 

were havinghigherbirthratesattheolderchildbearing ages than the cohorts preceding them. 

The members ofthesecohortsreachedtheearly


ages of childbearing during the 1930!s and early 

1940’s, when economic conditions and war may 

have made it advisable or necessaryto postpone 

marriage and childbearing. By 1950, however, 

when the women in these cohorts were 25-34 

years of.age, they were having children at the 

highest rates observed at these ages since the 

6 
cohorts of the 1890’s. By 1960 they were 35-44 

years of age, and theinflationary effect of their 

higher fertility had virtually run its course. 

A second and more important change in the 

timing of births was the trend toward younger 

marriage and younger childbearing by the cohorts 

of 1926-35 (approximately). The women in these 

groups were 15-24 years of age in 1950, their 

marriage rates were high, and their birth rates 

at these ages were higher than any previously 

observed in this country in a series going back 

to 1917. Their higher fertility at the younger 

ages kept annual birth rates high throughout the 

1950’s. 

Because these women had such high birth 

rates at younger ages in the 1950’s, they are 

having relatively low rates at the older childbearing ages in the 1960’s. This means that cohorts with relatively low birth rates at the older 

childbearing ages (the 1926-35 cohorts, approximately) have replaced cohorts with relatively 

high rates at these ages (the cohorts of 1916-25, 

approximately). The result is that fertility rates 

at ages 25 and over are substantially lower in the 

1960’s than in the 1950’s. This can be seen from 

comparisons of age-specific birth rates presented in figure 3 and table 3. 

Younger childbearing increases the proportion of women who have aIl the children they want 

by a given age and thereby reduces the proportion of women who want additional children at 

later ages. This effect is illustrated by figure 4, 

which shows the proportions of women who have 

had various numbers of children by age 30. The 

proportion who have had three children or more 

has doubled in 20 years, This shift toward more 

children has greatly reduced the proportions of 

childless women and of those with one child, and 

since 1955 it has also brought down the proportion 

of women with only two children. 

Between January 1,1957, and January 1,1965, 

tie proportion of 30-year-old women with three 

children or more rose from 36 to 50 percent. This 

means that the proportion with fewer than three 

children by age 30 has dropped from 64 to 50 percent. Because most of the women who want additional births are among those with fewer than 

three children, the reduction in this proportion 

implies a reduction in birth rates after age 30. 

400 

-%+, 

200 .fi”— /-@---

l“0 \4-- ‘“””-”=--0’- “---

/“;:>:$;’ 

/ / 

z I 

; too —


o


>


~ 80


0 

0 

_. 

~ 60


u


n


w


1-


< 40
 z


20 

YEAR 

Figure 3. Birth rates by age of mother. 

(For 1959-6+ based on registered 1 ive births; for 

1940-59. on 1 ive births adjusted for underreg istrat ion’. Semi logarithmic ;cale) 

Fertility at “Younger Ages 

The explanation offered in me preceding section accounts only for the decline in fertility at 

the older childbearing ages. Fertility has also 

fallen at the younger childbearing ages (under 25 

years of age, approximately), as is shown by the 

age-specific birth rates in table 3 and figure 3. 

One or both of two tendencies could account for 

this trend: 

1.	 postponement of births to latev ages.— 

Perhaps today’s young couples are shifting their childbearing to somewhat later 

ages than the cohorts immediately preceding them. This would amount to a re7 
Table 3. Birth rates by age of mother: United states, 1940-64 

Year 

Registered births 

1964-------------------------

1963-------------------------

1962-------------------------

1961-------------------------

1960-------------------------

1959-------------------------

Births adjusted foer 

underreg~stratlon 

1959-------------------------

1958-------------------------

1957-------------------------

1956--------------------------

1955-------------------------

1954-------------------------

1953-------------------------

1952-------------------------

1951-------------------------

1950-------------------------

1949-------------------------

1948-------------------------

1947-------------------------

1946-------------------------

1945-------------------------

1944-------------------------

1943-------------------------

1942-------------------------

1941-------------------------

1940-------------------------

[Notes to tables give. o, page VII] 

Age of mother 

10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 

years years years years years years years yearsl 

Rate per 1,000 women 

0.9 72.9 219.8 178.8 103.5 49.9 13.8 0.8 

76.5 231.3 185.4 105.9’ 51.2 14.2 

::: 81.3 243.8 191.3 108.7 52.6 14.8 %; 

0.9 88*O 253.6 197.8 113.3 55.6 15.6 0.9 

89.1 258.1 197.4 112.7 56.2 15.5 0.9 

::: 89.1 257.5 198.6 114.4 57.3 15.3 0.9 

0.9 90.4 260.1 200.5 115.6 58.2 15.5 

0.9 ;;.; 258.2 198.3 116.2 58.3 ::.$ N 

260.6 199.4 118.9 59.9 1.1 

N 94:6 253.7 194.7 117.3 59.3 16:3 1.0 

0.9 90.5 242.0 190.5 116.2 58.7 16.1 1.0 

0.9 90.6 236.2 188.4 116.9 57.9 16.2 1.0 

88.2 224.6 184.1 113.4 56.6 15.8 1.0 

k; 86.1 217.6 182.0 112.6 55.8 15.5 1.3 

0.9 87.6 211.6 175.3 107.9 54.1 15.4 1.1 

1.0 81.6 196.6 166.1 103.7 52.9 15.1 1.2 

1.0 83.4 200.1 165.4 102.1 53.5 15.3 1.3 

81.8 200.3 163.4 103.7 54.5 15.7 

::! 79.3 209.7 176.0 111.9 58.9 16.6 H 

0.7 59.3 181.8 161.2 108.9 58.7 16.5 1.5 

0.8 51.1 138.9 132.2 100.2 56.9 16.6 1.6 

0.8 54.3 151.8 136.5 98.1 54.6 16.1 1.4 

0.8 61.7 164.0 147.8 99.5 52.8 15.7 1.5 

0.7 61.1 165.1 142.7 91.8 47.9 14.7 

56.9 145.4 128.7 85.3 46.1 15.0 H 

H 54.1 135.6 122.8 83.4 46.3 15.6 1.9 

lRates computed by relating births to mothers aged 45 years and over to women aged 

45-49 years. 

versal of the trend toward earlier child- elusion of the other. Both are probably correctto 

bearing. a limited extent. (See .JJatality Statistics Arzdysis, 

2. Smaller families. —Perhaps young coup1963,2 for a discussion ofthe,evidenceconcerning 

les will have fewer children altogether trends in fertility at the younger childbearing 

than the couples who began their families ages.)


earlier in the postwar period. The downward trend inthefertilityof younger


women is illustrated by the cumulative fertility 

At the present time, there isno reason for pre- rates for ages 18-24 for the cohorts of1910 and 

ferring either of these explanations to the ex- later (fig. 5). Recent cohorts have had fewer 

8 
.

COHORT 

PERCENT 1890 1900 1910 1920 1930 

4C 

20 

10 

8 

6 

. 

4 

2 

I 

1917 1920 1930 1940 [950 1960 I 970 

YEAR ATTAINEO AGE 30 

Figure 4. Percentage of women with specified number of births by exact age 30 on January [.


(Semi logarithmic scale)
 243-645 0 -67-3 9 
2000 

EXAGT AGE 

1000 

800 

z 

E 

0 

s 4@3 

0 

g. 

m 

u 

0. 

; 200 I 

a 

100 

‘owl 

~ 

1910 1930 1940 195C 

COHORT 

Figure 5. Cumulative birth rates by exact ages’ 

18-2! years. 

(Rates based on births adjusted for underregistration for all years, including 1960-6W, and on 

population est~mates adjusted for underenumeration. Semilogarithmic scale) 

children than the cohorts immediately preceding 

them, but their cumulative fertility is still well 

above the levels observed for the cohorts of 

1910-20. 

The recent experience of the 1947 cohortis 

of interest because this was the largest cohort 

born in the early postwar period. There has been 

some speculation that when the women ofthiscohort became old enough to marry, they wouldbe 

unable to find husbands at the appropriate ages 

(generally 2 to 3 years older) because of the 

different sizes of the cohorts involved. Speaking 

approximately, the women of the 1947 cohort 

would ordinarily marry menfromthe 1944cohort, 

but there were 23 percent fewer children bornin 

1944 than in 1947, so there are proportionately 

fewer men available for marriage. Some ofthis 

slack is undoubtedly taken care of by women 

marrying younger men. But the sharp drop in the 

cumulative fertility rate for the 1947 cohort at 

age 18 (fig. 5) may result from a corresponding 

drop in the marriage rate for these women. Unfortunately, statistics on marriages arenotsufficiently detailed to test this explanation. However, cumulative birth rates at ages 16 and 17 

(not shown) also make thesame dip forthe 1947 

cohort and a recovery for the 1948 cohort. 

Influence of Contraceptive” Pills 

The effects of theincreased useofthecontraceptive pill on recent trends infertility are not 

yet known. Certainly thepill hashad some effect 

independent of the many factors enumerated 

above, but we do not know how large it has been. 

To a considerable extent, the decline infertility 

is the expected result of certain shifts in the ages 

at which women bear children. The recent tendency 

for couples to have their children somewhat later 

in life and, possibly, to have fewer children altogether has undoubtedly been aided by the use of 

the pill, but there is no evidence concerningthe 

pill’s independent effect on these trends. (See a: 

Na.tality Statistics Analysis, 1963,2 for estimates 

of numbers of women using contraceptive pills 

and a discussion of the possible influence on fertility of the pill.) 

The Childbearing Population 

The only factor influencing future births about 

which we can be reasonably certain is the size of 

the childbearing population. The large number of 

babies born in 1947 became 18 years of age in 

1965. Those born in 1948 and subsequent years 

will soon follow them and greatly increase the 

number of young people in the younger childbearing ages. There were 6.8 million women at 

ages 20-24 in 1965. By 1970 there will be 8.6 

million women in this age group, 26 percent 

more, according to the Census Bureau’s projections. 5 

It is quite possible that the increasing number 

of young people will offset declining birth rates 

enough to produce an upturn in the annual number 

of children born. Even the Census Bureau’s low 

10 
series of projections shows a rise in annual numbers of births starting in the late 1960’s and proceeding through the 1970’ s.” 

In summary, there is a potential for an increase in the annual number of births within the 

next 5 or 10 years. When a rise will begin and 

how great it will be are questions that can receive 

only speculative answers at present. 

THE FERTILITY OF MAJOR 

POPULATION GROUPS 

The foregoing discussion deals with fertility 

trends in the United States as a whole. Obviously 

the same description does not necessarily apply 

to all components of the population. In this section of the report, attention will be directed toward the fertility of certain major population 

groups. 

The kinds of groups available for comparative 

analysis are necessarily limited by the inf ormation collected on birth certificates. Consequently, 

comparisons of the fertility of certain important 

groups in our society cannot be made. For example, it is impossible to discover from birth registration data whether fertility is declining more 

rapidly among low-income families than among 

moderate- and high-income families. Nor is it 

possible to investigate trends in fertility among 

women classified by educational attainment. It 

would be highly desirable, for many purposes, 

to present such analyses, but the birth certificates of most registration areas do not ask for 

the information needed to make this possible. 

However, Puerto Rico has requested information 

pertaining to the educational attainment of the 

mother and father on its birth certificates since 

1962. Minnesota also instituted this practice on 

the 1965 revised form of its birth certificate. 

At present, the only major population groups 

whose fertility can be studied on the basis of information collected on birth certificates are those 

identified by race and residence. The next section 

compares fertility in the white and nonwhite populations, and the two following sections present 

data for States, geographic divisions, and certain 

metropolitan areas. 

Fertility by Color 

The fertility of the nonwhite popidation has 

been higher than that of the white population in 

all years for which relevant data are available. 

In 1964, the excess of the fertility rate (births 

per 1,000 women 15-44 years of age) for non­

“whites over that for whites was 42 percent. 

In general, both the white and nonwhite populations have followed similar trends, as the fertility rates shown in figure 6 indicate. However, 

the postwar rise in fertility was somewhat more 

rapid for the nonwhite population. Measuring from 

the low prewar levels observed in 1933-39, the 

rise to the 1957 peak was 58 percent for the white 

population and 65 percent for the nonwhite. So far, 

fertility rates for the two major population groups 

have shown no tendency to converge. 

In considering fertility trends in the nonwhite 

population, the question arises as to whether this 

group has shown the same kinds of changes in the 

timing of births and completed fertility that have 

been described for the total population. Only approximate answers can be given to such questions 

at the present time because cohort fertility tables 

have not been developed for the nonwhite population. 

It is clear from census data that the completed fertility of nonwhite cohorts has risen 

substantially-probably by a greater relative 

amount than for white cohorts. Among nonwhite 

women who had ever married, the lowest completed fertiIity rate was 2,742 children ever born 

per 1,000 women for the cohorts of 1906-10 (approximately). This rate was computed from reports of women who were 50-54 years of age at 

the time of the 1960 census. G In 1964 a Census 

Bureau survey showed that ever-married nonwhite 

women 30-34 years of age had already borne an 

average of 3,841 children per 1,000 women.7 This 

rate relates to the cohorts of 1930-34 (approximately). So by 1964 nonwhite wives in the cohorts 

of 1930-34 had already borne 40 percent more 

children than were borne altogether by wives in 

the cohorts of 1906-10. By the time the cohorts 

of 1930-34 reach the end of the childbearing period, their fertility will exceed that of the 1906-10 

cohorts by an even greater amount. 

11

o T T T 

1920 1930 1940 1950 1960 1970 

YEAR 

Figure 6. Ferti 1 ity rates by color. 

(Rates per 1,000 women aged 15-W years. For 1959-64 based on registered Jive births; for 1920-59, on


live births adjusted for underregistration)


Comparable statistics for white ever-mar- relate to ever-married women rather than all 

ried women, in contrast, show a rise ofonly22 women and since the younger cohorts havenotyet 

percent from the cohorts of 1906-10 to thoseof completed their fertility, they are the best data 

1930-34. This is based on an average of2,317 available at the present time. The contrast bechildren ever bornebywhiteever-marriedwomen tween the rise in the rates for the ever-married 

50-54 years old in 19606 and an average of2,825 white and nonwhite women is large enoughtosupfor comparable women 30-34 years oldin 1964.7 port the hypothesis that the completed fertility 

Although these statistics are not ideal for rates for cohorts of nonwhite women have risen 

comparing trends in completed fertility forco- more rapidly than those for cohorts of white 

horts of white and nonwhite women since they women. 

12


7 
------------

It is evident that the fertility of the nonwhite 

population was temporarily inflated during the 

1950’s by the same kinds of factors that have been 

described for the total population. The total fertility rate of the nonwhite population reached a . 

high of nearly 4,800 in 1957, and it seems unlikely 

that any cohort of nonwhite women then in the 

childbearing years of life would have such a high 

completed fertility rate. The evidence for this 

belief is less firm for the nonwhite population 

than for the total population, but a 1960 fertility 

survey suggests that currently married women 

in the cohorts of 1926-30 will have about 3,900 

births per 1,000 women.s Even if this proves to 

be an understatement of the eventual rate, it seems 

unlikely that the completed fertility rate for all 

nonwhite women in any recent cohort will be as 

high as 4,800. 

What gave rise to the inflation of total fertility rates to the levels of 4,700-4,800 in the late 

1950’s? For nonwhite women, the rise in the agespecific birth rates of older women appears to have 

played a greater part in the inflation of fertility 

than was the case for the white population. This 

can be seen from table 4, which shows the percentage change in age-specific rates for white and 

nonwhite women for the periods 1940-59 and 

1959-64.’ At ages 25 and over, the percentage increase in birth rates was considerably greater for 

nonwhite than for white women. Below age 25, the 

reverse was true: rates for white women rose 

faster than those for nonwhite. 

These data suggest that the shift of childbearing from older to younger ages was not as 

great for the nonwhite population as it was for the 

white population. This may have been due partly 

to the fact thatbirth rates were already quite high 

for younger nonwhite women. 

Since 1959 the age-specific birth rates for 

both white and nonwhite women have declined. So 

far the declines have been somewhat faster for 

‘The year 1959 is used in these comparisons rather than 

the peak fertility year of 1957 because two sets of rates are 

availa Me for 1959: one is comparable to the rates for 1940 

(based on births adjusted for underregistration), and the other 

is comparable to the rates for 1964 (based on registered births 

only). .41s0, rates for 1959 were not very different from those 

for 1957. 

white women, but the differences in trends at most 

ages are not great. 

At the higher birth orders, however, nonwhite 

rates have been falling faster than white rates. 

For example, between 1959 and 1964, the number 

of fifth and higher order births per 1,000 women 

15-44 years of age dropped by 13 percent for the 

nonwhite population and 6 percent for the white 

population. This comparison is based on the 

following figures: 

Percent 

change, 

1959 1964 1959-64 

White --------------- 16.0 15.’0 -6 

Nonwhite 48.8 42.3 -13 

The more rapid decline of nonwhite birth rates at 

the higher birth orders probably results from a 

greater abiliW to prevent unwanted births. A 1960 

survey of attitudes and behavior associated with 

family planning showed that nonwhite couples tend 

to want fewer children than white couples but have 

been much less successful than white couples in 

controlling their fertility to the extent desired. 9 

Perhaps the ability of nonwhite couples to control their fertility is improving. 

Comparisons of certain characteristics of 

white and nonwhite births (such as sex ratio, 

plurality, and period of gestation) are presented 

in later sections of this report. 

Fertility by States and Geographic Areas 

Levels. —Comparisons of birth rates by State 

for 1964 are presented in figure 7, which shows 

the State birth rate and its standing in relation to 

the national birth rate. Although the majority of 

the State birth rates were close to tie national 

average, a belt of high birth rate States extends 

from the South through the Southwest. Birth rates 

were also high in the outlying States of Alaska 

and Hawaii. On the other end of the scale, there 

were States with low birth rates scattered throughout other parts of the country. The lowest rate was 

17.9 births per 1,000 population in Oregon. 

The birth rates of the four geographic regions 

varied less than the rates for individual States. 

13 
----------------

----------------

----------------

----------------

----------------

----------------

----------------

----------------

----------------

----------------

----------------

----------------

Table 4. Birth rates adjusted and not adjusted for underregistration and percent 

change, by color and age of mother: United States, 1940, 1959, and 1964 

15-19 

20-24 

25-29 

:;-:; 

40:44 

15-19 

20-24 

25-29 

30-34 

35-39 

40-44 

Color and age 

White 

years 

years 

years 

years 

years 

years 

Nonwhite 

years 

years 

years 

years 

years 

years 

[Notes to tables given on page VII] 

Rates adjusted for Rates not adjusted 

underregistration for underregistration 

Percent 1940 1959 change 1959 1964 Percent 

change 

45.3 79.8 79.2 63.4 -20 

131.4 253.3 251.7 212.9 -15 

123.6 196.7 195.5 175.7 -10 

83.4 112.0 111.3 100.1 -10 

45.3 55.7 ;:.; 47.6 -14 

15.0 14.8 . 12.9 -12 

121.7 167.1 160.5 138.7 -14 

168.5 308.9 297.9 269.3 -10 

116.3 227.3 220.2 200.8 -9 

83.5 143.3 138.1 126.8 

53.7 78.5 75.0 67.5 -:: 

21.5 23.3 21.2 20,8 -2 

The birth rate in the West (21.1per1,000) was 

about the same as the national average (21.0). 

This is because the low birth rates in three 

continental Pacific Coast States were offset by 

high birth rates in the outlying States of Alaska 

and Hawaii .andin the Mountain States. The birth 

rate in the North Central Region was also the 

same as the national average. Thisleavesdeviant 

birth rates on the high side intheSouth (22.1) and 

on the low side in the Northeast (19.7). 

Regional differences in the birth rate, however, ~onotnecessarilycorrespondtodifferences 

in the fertility of women. AIthough the birthrate 

is an appropriate measure of the impact offertility on population growth, it has long been discredited as a measure of fertility, for itis affected by the proportions of women at the childbearing ages. It is also affected by theproportion 

of women who are married and bythe timingof 

their births. 

Table 5 shows regional fertility differentials 

in terms of more refined measures than thebirth 

rate. Varying proportions ofwomenineach5-year 

age group between ages 15 and44 are taken into 

account by computingan adjusted birthrate. The 

adjustment increases the comparative fertilityof 

the Northeast and North Central Regions,reduces 

that of the”South, and does not appreciably affect 

that of the West. The net effect of adjusted birth 

rates is to bring tlie regions closer together than 

do comparisons of unadjusted birth rates. 

The adjustment is basedontheindirect method of standardization, the standard age-specific 

birthrates being those for the total UnitedStates 

in 1960, This set of rates is weighted by the 

proportions of the regional population who were 

women in 5-year age groups between the ages of 

15 and 44 at the time ofthe1960 census. Although 

‘regional age-sex structures have changed since 

the 1960 census, the adjustmentsof the1964bi~th 

14 
/ 

1-

Figure 7. Birth rates by State, 196!.


(By State of residence)


rates are considered to be approximately correct. They show that the age-sex structure favors 

high birth rates in the South and low birthrates 

in the Northeast and North Central Regions. 

Table 5 also shows regional fertility differences in terms of the number of children ever 

born to women aged 15-44 by June 1964. This 

retrospective measure of fertili~ reflects the 

birth rates of these women in all of their childbearing years, to date, not just in 1964. These 

pretious years differ from 1964 in that regional 

differences inthe birthratewere formerlylarger 

and have since converged. Gwing to this convergence, regional differences in the number of 

children ever born should exceed regionaldifferences in the 1964 birthrate. 

Compared with a base of 100for the United 

States as awhole, regional indexes ofthenumber 

of children ever born per woman range from 88 

in the Northeast to 106 in theNorthCentral Region. That this index of fertility varies morethan 

the adjusted birth rate by region is seen in the 

sum of the deviations (without regard to sign) 

from 100. The deviations ofthe four regions’ indexes sum to 8forthe adjusted birth rate and26 

for the number of children ever born. 

A further refinement is introduced by study- “ 

ing the fertility of only those women who had 

ever married by June 1964. Table 5 shows that 

this refinement slightly reduces the range of the 

regional differences to 93-104. This reduction is 

15

--------------- ---------

-------------------

--------------- ---------

------------------------------

------------------

Table 5. Measures of fertility by geographic region:l United States, 1964


[Notes to tables @“.. on fxige VII] 

Region


All
 Meastireof fertility regions North- North


east Central South West


Birth rate per 1,000 total 

population ,.., 

.! 

Birth rate, unadjusted 21.0 19.7 21.0 22.1 21.1 

Birth rate, age-sex adjusted 21.0 20.1 21.4 21.4 20.9 

Number of children ever born 

Children ever born per woman aged 

15-442------------------------------ 1.93 1.69 2.05 2.02 i.99 

Children ever born per ever-married woman aged 15-443 2.51 2.33 2.62 2.57 2.45 

index


Birth rate, unadjusted 100 94 100 105 100 

Birth rate, age-sex adjusted 100 96 102 1(32 100 

Children ever born per woman aged 

15-442 100 88 106 105 103 

Children ever born per ever-married woman aged 15-443- 100 93 104 102 98 

lBy place of residence as of mid-1964. ‘1 

2U.S. Bureau of the Census,’’Fertility
of the Population, June 1964 and March 1962,” 

Current Population Reports, Population Characteristics,Series I?-20,No. 147, table 4, ~P. � or age. 

31bid.,p. 16. Figures are standardizedfor age.


broughtaboutbyomitting
never-marriedwomen,


whose fertility
 is low. By geographicregion,


never-marriedwomenconstitute
 thegreatestpro­


portionofwomen 15-44yearsofageintheNorth-


eastandthesmallestintheWest.Removalofthe


never-marriedwomen from thepopulation
 aged


15-44increasesthe averagenumber ofchildren


ever born in allregionsbutrelatively
 more in


the Northeastand relatively
 lessin the West. 

Recent treds. —The declineofthebirthrate 

inrecentyearshasbeengeneral, affecting
 every

Stateand geographic
regionoftheUnitedStates.


Between1960and 1964,thedeclines
 averagedll.4


percentbutvariedwidelyfrom StatetoState.
In


general,
theStatesintheWestand NorthCentral


Regions experiencedmore rapiddeclinesthan


Statesin the Southand Northeast.
Table6 and


figure8 show thepercentagedecline”of
 thebirth


rate in each Statebetween1960 and 1964.The


largestdeclinestookplaceintheeightMountain


States,where theyaveraged17.2percent.The


second largestdeclinestookplacein theWest


North CentralStates.
Declineswere leastinthe


EastSouthCentralDivision,
 where theyaveraged


9.0percent.Figure8 shows theserelative
de-


clines.


Sincethebirthrateisaffected
 by population


composition, notablyby proportions
 inthechild­


bearingages,comparativedeclinesin thebirth


rateare affectedly
changesintheseproportions.


16 
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---------------------------------------

-------------------------------------------

---------------------------------------

-------------------------------------------------

--------------------------------------------------

----------------------------------------------------

--------------------------------------------

--------------------------------------------------

---------------------------------------------

----------------------------------------------

-------------------------------------------------

-----------------------------------------------

---------------------------------------------

-----------------------------------------------------

--------------------------------------------------

-------------------------------------------------

-------------------------------------------------

------------------------------------------------

------------------------------------------------ ----------------------------------------- -----------

-------------------------------------------------

---------------------------------------------

---------------------------------------------

-------------------------------------------------

---------------------------------------------------

Table 6. Birth rates and percent change: United States, each geographic division and


State, 1960 and 1964


[Notes
totables given on page VII] 

Division and Statel 1960 I 1964	 Percent


change


1 I 

Birth rate per


1,000 population ‘


United States 23.7 21.0 -11.4 

Geographic’ division


New England2--------------------------------------------- 22.5 20.2 -10.2


Middle Atlantic 21.5 19.5 -9.3


East North Central 24.2 21.3 -12.0


West North Central 24.0 20.6 -14.2


South Atlantic 24.2 21.9 -9.5


East.South Central 24.4’ 22.2 -9.0


West South Central-------------------------:------------- 25.4 22.4 -11.8


Momtain 27.3 22.6 -17.2


Pacific 23.6 20.5 -13.1


New Eruzland


Maine 24.0 21.5 -10.4 

New Hampshire 22.8 21.1 -7.5 

Vermont 24.1 21.2 -12.0 

Massachusetts2------------------------------------------- 22.4 19.6 -12.5 

Rhode Island 21.4 19.7 -7.9 

J Connecticut 22.4 20.6 -8.0 

Middle Atlantic 

New York 21.4 19.6 -8.4 

New Jersey 21.8 19.8 -9.2 

Pennsylvania 21.3 19.1 -10.3 

East North Central 

Ohio 23.8 20.8 -12.6 

Indiana 24.2 22.0 -9.1 

Illinois 23.7 21.2 -10.5 

Michigan 25.0 21.7 -13.2 

Wisconsin 25.2 21.6 -14.3 

West North Central 

Minnesota 25.7 21.8 -15.2


Iowa -
 23.3 20.1 -13.7


Missoui 22.7 20.1 -11.5


North Dakota 26,3 22.4 -14.8


South Dakota 25.9 21.8 -15.8


Nebraska 24.3 20.8 -14.4


Kansas 23.3 19.5 -16.3


by place of residence.


%’igures for 1964 exclude 1,800 live births in Massachusetts.


17

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Table 6. Birth rates and percent change: United States,


State, 1960 and 1964—Con.


[Notes to tables given cm page VII] 

Division and Statel


South Atlantic


Delaware


Maryland


District of Columbia


Virginia


West Virginia


North. Carolina


South Carolina


Georgia


Florida


East South Central


Kentucky


Tennessee


Alabama


Mississippi


West South Central


Arkansas


Louisiana


Oklahoma


Texas


Mountain


Montana


Idaho


Wyoming


Colorado


New Mexico


Arizona


Utah


Nevada


Pacific


Washington


Oregon


California


Alaska


Hawaii


1

By place of residence. 

18


each geographic division and


Percent
 1960 1964
 change


Birth rate per


1,000 population


25.9 23.3 -10.0 

24.9 22.9 -8,0 

26.0 24.0 -7.7 

24.1 22.1 -8.3 

21.2 19.8 -6,.6 

24.1 21.9 -9.1 

25.1 22.3 -11.2 

25.3 23.4 -7.5 

23.3 20.0 -14.2 

23.8 21.5 -9.7


23:0 21.1 -8.3


24.7 22.4 -9.3


27.2 24.5 -9.9


22,7 21.4 -5.7 

27.7 24.8 -10.5 

21.9 19.3 -11.9 

26.0 22.5 -13.5 ‘ 

25.9 21.4 -17.4


25.7 20.3 -21.0


23.8 21.1 -18.2


24.5 20.7 -15.5


32.3 26.6 -17,6


28.2 23.0 -18.4


29.5 24.1 -18.3


25.5 24.6 -3.5


22.9 19.1 -16.6


21.7 17.9 -17.5


23.7 20.7 -12.7


33.4 29,1 -12.9


27.2 24.8 -8.8

Reldi,e declime 

Percmt declina (Us. decline = 100) 

160 or more - !40 or more 

13.0- 15.9 mm 114-139 

10.0-129 m 8s -113 

7.0 - 99 - 61-87 

6.9 or less m 60 or 10s5 

v 4 HAM[All 

Figure 8. Percent change in birth rates by State, [960-64. 

(By State of residence) 

kthe NIountain Division, forexample,thel 960-64 women than for nonwhite. The magnitude of redecrease in the proportion of the total population cent declines in the birth rate by geographic diviof reproductive age (18-44) was 2.2 percem.lo sion is consistent with this relationship. Between 

This in itself would account for a decline of the 1960 and 1964 declines in the birth rate were 

birth rate during the period ofabout 2.2 percent, smallest in the East South Central Division and 

whichis approximately one-eighthof thetotalde- the Middle and South Atlantic Divisions, which 

cline. In general, the 1960-64 decline of a State generally have high proportions of nonwhite perbirth rate was to some extent explained by a de- sons. In areas with smaller proportions of noncline in the proportion of its population of repro- white persons, birth rates have tended to decline 

ductive age. somewhat more rapidly. 

In addition tothe age composition, the color The 1960-64 decline of the birthrate was also 

composition of State populations may affect the related to the leveI of the birth rate at the begincomparative declines of their birth rates. The ning of the period. Birth rates have declined most 

previous section of this report, “Fertility by in areas where they were highest and least in 

Color,” showed that since 1959 age-specific birth areas where they were lowest. As a result, rerates have been declining more rapidly for white gional differences in birth rates have diminished. 

19 
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In 1960, for example, birth rates by geographic 

division ranged between 91 and 115 percent of the 

national average. In 1964 this range bad harrowed 

to 93-108 percent. In table 7 these figures are 

represented by an index birth rate for each of the 

nine geographic divisions, the index for the Nation as a whole being 100. 

Table 7. Index of birth rates by geographic division: United States, 1960 

and 1964 

[Notes ta tables given on page VII] 

I I 

Divi_sionl 1960 1964 

United States 100 100 

New England2----------------- 95 96 

Middle Atlantic 

East North Central 1:: 1;? 

West North Central 101 

South Atlantic 102 1:: 

East South Central 103 106 

West South Central 107 107 

Mountain 115 108 

Pacific 100 98 

IBY place of residence. 

2Figures for 1964 exclude 1,800 live 

births in Massachusetts. 

Reductions of the variation between States 

can also be seen with the use of the coefficient 

of variation, which is the standard deviation of 

State birth rates as apercentage of the average 

birth rate for all States. In 1964, the coefficient 

of variation was 9.5 percent; it was 10.1 percent 

in 1960and 15.6 percentin 1940. 

Fertility by Metropolitan Residence 

There were 2,587,410 births registered to 

residents of metropolitan counties of the United 

States during 1964, or 64 percent of the total. 

Metropolitan counties are those defined by the 

U.S. Bureau of the Census as being in standard 

metropolitan statistical areas (SMSA’S). Essentially, an SMSA is a county containing a.cityof 

50,000 inhabitants ormore; further details of the 

definition are given in the Technical Appendix 

of Volume I of Vital Statistics of the United 

States, 1964.1 

“Birth ratesfor largeSMSA’svaried accor&g 

to the geographic region in wbich they were situated, as shown in table 8. They”were high in the 

South and North Central Regions and low inthe 

Northeast. Birth rates for SMSA’S in the West 

Region were close to the national average of21.O 

per 1,000 population. 

Although the majority of the SMSA’s (21’of 

37) had birth rates above the national figure, the 

average SMSA birthrate unweightedbypopulation 

size was 21.2per 1,000. This is veryclose to the 

national birth rate. Thus birth rates give about 

the same impetus to populationgrowth inthelarge 

SMSA’sas inthe Nation as awhole. 

Between 1960 and 1964 birthrates declined 

most in the metropolitan areas where they were 

highest. Table 8showsthe percent decline of the 

birth rate during this period for the 371argest 

SMSA’s. The annual birth rates for1960 and.1964 

are also given in that table. To insure comparability, the 1960 territory ?fthe SMSAis used and 

subsequent annexations are disregarded. 

The average. decline of’ the birth rate in the 

37 largest SMSA’S was 12.1 percent, or 1.o6 

times the national decline between 1960 and1964. 

Declines during this period exceeded the national 

average of 11.4 percent in 22 of the 37 largest 

SMSA’S. In the 31argest SMSA’s-New York, LQS 

Angeles, and Chicago- however, declines were 

less than the national average. 

The more rapid declines ofbirth rates inthe 

largest SMSA’S were insufficient to offset their 

more rapid population growth as compared with 

the total United States. According torecent Census Bureau estimates, the population of the 37 

largest SMSA’s shown here increased by7.4 percent between 1960 and 1964 and the total population increased by 6,7 percent.11 

Although the birthrates cited above showthe 

contribution of fertility to population growth in 

metropolitan areas, theyareinadequate measures 

of fertility. Census Bureau data on thenurnber.of 

children ever borne by ever-married women of 

reproductive age show that fertility was lower 

in metropolitan areas than in other areas. Among 

women aged 15-44 who had ever married, those 

living in metropolitan areas had borne an average 

of 2.4 children by June 1964; the comparable figure for those living in nonmetropolitan areas was 

20 
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Table 8. Birth rates for standard metropolitan statistical areas and percent change:


United States, 1960 and 1964


[Notestotables
 ghw.o.pageVII]


Region and SMSAl 1964 1960	 Percent


change
 I I 

Northeast Birth rate per


(’ 1,000 population


Boston-Lowell-Lawrence, Mass2---------------------------- 20.1 22.5 -10.7 

Buffalo, N.Y--------------------------------------------- 20.0 23.6 -15.3 

Newark, N.J---------------------------------------------- 19.8 21.2 -6.6 

New York, N.Y-------------------------------------------- 19.5 20.5 -4.9 

Paterson-Clifton-Passaic, N.J---------------------------- 18.5 20.2 -8.4 

Philadelphia, Pa.-N.J 20.3 22.7 -10.6 

Pittsburgh, Pa------------------------------------------- 18.2 21.3 -14.6 

Providence, R.I------------------------------------------ 19.3 21.1 -8.5 

Rochester, N.Y------------------------------------------- 21.8 22.7 -4.0 

North Central 

Chicago, Ill--------------------------------------------- 21.9 24.6 -11.0 

Cincinnati, Ohio-Ky 22.7 25.7 -11.7 

Cleveland, Ohio 20.5 22.9 -10.5 

Columbus, Ohio 23.0 26.6 -13.5 

Dayton, Ohio 21.4 25.1 -14.7 

Detroit, Mich 20.9 24.6 -15.0 

Indianapolis, Ind---------------------------------------- 23.7 27.0 -12.2 ‘ 

Kansas City, Mo.-Kans 21.6 25.8 -16.3 

Milwaukee, Wis------------------------------------------- 22.1 26.0 -15.0 

Minneapolis-St. Paul, Mien 23.9 27.5 -13.1 

St. Louis, Mo.-I11--------------------------------------- 21.9 25.0 -12.4 

South


Atlanta, Ga---------------------------------------------- 23.5 25.6 -8.2


Baltimore, Md-------------------------------------------- 21.9 24.5 -10.6


Dallas, Tex---------------------------------------------- 22.6 25.8 -12.4


Houston, Tex--------------------------------------------- 23.0 26.8 -14.2


Louisville, Ky.-Ind’ 21.8 25.9 -15.8


Miami, Fla----------------------------------------------- 17.8 21.0 -15.2


New Orleans, La------------------------------------------ 24.0 27.0 -11.1


San Antonio, Tex----------------------------------------- 25.3 28.6 -11.5


Tampa-St. Petersburg, Fla-------------------------------- 17.3 19.9 -13.1


Washington, D.C.-Md.-Va 24.2 26.0 -6.9


West


Denver, Colo 21.2 25.6 -17.2


Los Angeles-Long Beach, Calif 20.9 23.1 -9.5


Portland, Oreg.-Wash 17.7 21.1 -16.1


San Bernadino-Riverside-Ontario, Calif 21.4 24.7 -13.4


San Diego, Calif 21.6 26.1 -17.2


San Francisco-Oakland, Calif 20.9 23.4 -10.7


Seattle, Wash 19.0 23.0 -17.4


—


!By place of residence; SMSA’S are those established in 1960.


2Figures for 1964 exclude 1,800 live births in Massachusetts and a smaller but un­


known number in the Boston-Lowell-Lawrence SMSA.


21


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Table 9. Live births by sex and sex ratio 

States, 

[Notes to tables 

Color and plurality 

Total 

Single 

Plural 

Wite 

Single 

Plural------------------------------------------R------

Nonwhite 

Single 

Plural 

2.7.12 The lower fertility of the metropolitan 

population is also shown by percentage who had 

ever borne 5 children or more. Inthe age group 

35-44, which is near the completion of childbearing, 14.4 percent of the metropolitan wives 

had borne 5 children or more and 23.1 percent 

of the nonmetropolitan .13 

CHARACTERISTICS OF BIRTHS 

The following sections deal with certain 

characteristics of births for which all or most 

regis~rationareas provideinformation. Thecharacteristics for which data can be presented are 

necessarily limited by the information collected 

on the birth certificate; there are certain important characteristics, especially those relatingto 

the health of the newborn childor itsmother, for 

which there is little or no useful information at 

present. 

Sex Ratio -

The sex ratio of infants born in 1964 was 

1,047 males per l,OOOfemales, slightlylowerthan 

at birth, by color and plurality: United 

1964 

given on page VII] 

Ratio 

~ 

Males 

per Number 1,000 

females 

2,060,162 1,967.328 1,047 

2,019,630 1,927,704 1,048 

40,532 39,624 1,023 

1,727,416 1,641,744 1,052 

1,695,472 1,610,726 1,053 

31,944 31,018 1,030 

332,746 325,584 1,022 

324,158 316,978 1,023 

8,588 8,606 

at any time in the past 25 years. Between 1940 

and 1963, the sex ratio at birth varied withina 

narrow range between l,048andl,058. 

The sex ratio for nonwhite births was lower 

than for white births regardless ofother factors 

under consideration. In 1964 the sex ratio for 

white births was 1,052 and that for nonwhite 

births was l,022. However, there were wide differences between the sex ratios for various nonwhite groups. 

Sex ratio 

AII nonwhite groups- 1,022 

Negro --------------- 1,020 

Indian --------------- 1,016 

Chinese 1,122 

Japanese 1,073 

Other races 1,038 

A comparison between thesexratiofor single 

and plural births shows that single births had a 

higher proportion of males than live births in 

plural deliveries. There was aconsiderabledif~ 

ference between white and nonwhite births regardless of plurality (see table 9). 

22 

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Table 10. Sex ratio at birth, by live-birth order, race, and age of mother: United


States, 1964


[Notes tJJ tables given 011
pageVII]


Live-birth order


Race and age of mother
 R7r=t Second Third Fourth Fifth a~:er 

Total Males per 1,000 females


All ages---------------- 1.047 1.058 1.048 1.050 1.042 1,037 1,026 

15-19 years 1,056 1>065 1,035 1,032 1,034 1,118 i,.378 

20-24 years 1,050 1,054 1,053 1,046 1,036 1,058 1,000 

25-29 years 1,047 1,049 1,049 1,053 1,047 1,033 1,032 

30-34 years 1,039 1,066 1,030 1,056 1,037 1,025 1;031 

35-39 years 1,039 1,047 1,056 1,050 1,052 1,046 1,022 

40-44 years 1,029 1,064 1,052 1,060 1,023 1,038 1,014 

White


All ages---------------- 1,052 1,061 1,052 1,053 1,046 1,041 1,037 

15-19 years 1,066 1,074 1>042 1,046 ‘1,084 833 1,154 

20-24 years 1,053 1,056 1,055 1,048 1,041 1,073 1,014 

25-29 years------------------- 1,051 1,050 1,052 1,055 1,053 1,037 1,037 

30-34 years------------------- 1,046 1,063 1,041 1,061 1,041 1,034 1,039 

35-39 years 1,044 1,053 1,049 1,046 1,048 1,041 1,040 

40-44 years 1,044 1,073 1,067 1,073 1,026 1,056 1,029 

Nonwhite


All ages 1,022 1,035 1,021 1,032

- 1,019 1,020 1,004 

15-19 years 1,026 1,030 l,oi9 1,013 997 1,285 1,500 

20-24 years 1,034 1,039 1,039 1,039 1,022 1,038 990 

25-29 years 1,022 1,038 1,008 1,035 1,011 1,017 1>025 

30-34 years 

35-39 years 

1,002’ 

1,016 

1,090 

998 

929 

1,122 

1,004 

1,093 

1,007 

1,098 

974 

1,087. 

1,:); 

40-44 years ’959 981 917 929 982 894 968


Negro


All ages 1,020 1,031 1,021 1,030 1,017 1,017 1,005


15-19 years 1,024 1,026 1,020 1,015 995 1,292 1,458


20-24 years 1,032 1,034 1,038 1,040 1,017 1;042 991


25-29 years 1,019 1,033 1,006 1,024 1,011 1,010 1,027


30-34 years----------d 1,003 1,090 925 1,008 1,017 970 1,014


35-39 years 1,011 1,011 1,109 1>084 1,080 1,068 978


40-44 years 960 916 945 915 1,000 911 969


23


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Table 11. Number of live births in plural


deliveries and ratio of plural live


births to total live births: United 

States, 1944, 1950, and 1956-64 

[Notestotables @“,, cm page VII] 

Table 12. Ratio of plural live births to 

total live births, by”color and age of 

mother: United States, 1964 

[~ot.s to tables givenonpageVII] 

Age of mother Total White ::;e 

,, , 

Ratio of plural live


Year


1964----------

1963----------

1962----------

1961----------

1960----------

1959----------

1958----------

1957----------

1956----------

1950----------

1944----------

Number of


live births Ratio


in plural per 1,000


deliveries live births 

80,156 19.9 

81,158 19.8 

81,306 19.5 

86,100 20.2 

86,684 20.4 

87,654 20.6 

86,610 20.6 

87,158 20.5 

88,816 21.3 

74,456 20.9 

56,362 20.2 

All ages----


15-19 years 

20-24 years 

25-29 years 

30-34 years 

35-39 years 

40-44 years 

births per 1,000 

total live births 

19.9 18.71 26.3 

I 

12.5 11.8 14.8 

16.7 15.6 23.3 

21.5 20.0 30.7 

26.9 25,2 36.2 

29.4 27.6 39.2 

24.0 22.3 32.9 

As in the past, the sex ratio for 1964 

generally decreased with age ofmother and livebirth order; however, this relationship did not 

usually hold true for a cross-classification of 

any single birth order with age of mother, as 

shown in table 10. 

Plural Births 

Over the past 20 years there has been no 

noticeable trend in therateofoccurrence ofplural 

births (see table 11). Ninety-eight percent of the 

births occurred in single deliveries. Very little 

change can be seen in the relationship between 

age ofmother and the occurrenceofpluralbirths. 

‘l%e incidenceof plural births increased with age 

of mother through age 39 and decreased slightly 

over 40 (see table 12). 

While lin501ive births occurred ina plural 

delivery, this was not true for all races; lin 

every 54 white live birtha was from a plural 

delivery but 1 in only 38 nonwhite live births. 

Orientals had a lower twinning rate than white 

persons. 

Since the frequency of twins increased with 

bigher birth order, the high Negro twinning rates 

may be due partly to the large proportion of 

higher order births among them. 

Attendant at Birth and Place 

of Delivery 

In 1964 the vast majority oflive births were 

classifiedas having been delivered byphysicians 

in hospitals. This group consists of all births in 

hospitals and those births delivered in ’’clinics” 

by physicians. 

Using thisdefinition, figuresfor1963and 1964 

show no change in the proportion ofwhitebirtk 

delivered byphysicians in hospitals, but for nonwhite births the proportion rose from 87.9t089. O 

percent. 

In 1964 there were more white births delivered by physicians in hospitals than nonwhite 

births, as the following figures show: 

All White Nonwhite 

births biyths bivths 

Total 100.0 100.0 100.0 

Physician in 

hospital 97.5 99.1 89.0 

Physician not in 

hospital 0.7 0.4 2.0 

Midwife ---------- 1.5 0.3 8.0 

Other and not 

specified---- 0.3 0.2 1.0 

24 
The largest increases in the proportions of 

nonwhite births delivered by physicians in hospitals occurred in the geographic divisions where 

these proportions were smallest-the South Atlantic (82.4 to 83.9 percent) and the East South 

Central (65.4 to 67.4 percent). 

In certain geographic divisions there were 

- small declines in the proportion of hospital births. 

In five of the”nine divisions, over 99percent of all 

births occurred in hospitals. 

Table 13 is a percentage distribution of 1964 

births by place of delivery and person in attendance 

as recorded on the birth certificate. Since this 

table makes a distinction between births occurring 

in hospitals and those in clinics, it indicates that 

2.2 percent of the births classified as occurring 

in hospitals were reported to have occurred in 

clinics. Further, while most hospital births were 

delivered by physicians, a very small proportion 

were delivered by midwives (O.1 percent for the 

United States) and 2.4 percent were delivered by 

other and unspecified persons. It seems likely 

that most of the attendants in the latter category 

were physicians whose handwriting was so illegible that their titles were not distinguishable. 

Many of the midwives belong to a group of 

registered nurses trained in obstetrics who are 

known as *’certified nurse midwives.” New York 

had the largest number of babies delivered in 

hospitals by midwives (1,886). The remainder of 

the 3,902 were delivered in several other States. 

Usually the number for a State is less than 300— 

a group small enough that one or two persons 

could reasonably deliver all of them in a year. No 

complete investigation of these births has been 

made. If the number of deliveries conducted by 

nurse midwives in hospitals increases, more attention will be focused on them in the future. 

Only 4.8 percent of all births occurred outside hospitals; 2.9 percent of these were delivered 

by physicians, 1.5 percent by midwives, and 0.3 

percent by other and unspecified persons. 

In some States where a large proportion of 

births occur outside hospitals, most of them are 

delivered by rnidwives-Alabama, Georgia, and 

Mississippi. There are other States where a large 

proportion of births occur outside hospitals but 

they have the benefit of a physician in attendance— 

Arizona, Kansas, and Nevada. Arkansas, South 

Carolina, and Texas have large numbers of births 

outside hospitals delivered by both physicians and 

midwives. 

Birth Weight and Period of Gestation 

The weight of an infant at birth is one of the 

most easily obtained indicators of his maturity 

and, at certain levels, a good predictor of his 

future health. Infants weighing less than 2,501 

grams or more than 5,000 grams have high risks 

of neonatal mortality. It has recently been shown 

that the “immature” babies (those weighing less 

than 2,501 grams or 5 pounds, 9 ounces) also have 

higher risks of morbidity if they survive and may, 

in fact, never quite catch up in physical. and 

intellectual growth with the more mature members 

of their cohort. 14 

In I?atality Statistics Analysis, United States, 

1962,15 there is a detailed discussion of the 

trends in birth weight and gestation distributions 

since 1950. Since there have been no noticeable 

changes in the trend since 1962, further discussion 

is umecessary; therefore this section considers 

several of the environmental and biologic variables that are associated with variation in birth 

weight and gestation. 

There is an important differential in birth 

weight between white and nonwhite babies. The 

median weight for white infants (3,320 grams) 

in 1964 was 190 grams higher than for nonwhite 

infants (3,130 grams). This was due to a much 

larger proportion of immature births among nonwhite babies (13.9 percent) than among white 

(7.1 percent). 

This differential can probably be attributed 

to poorer access to good prenatal care, poorer 

nutrition on the part of the mother, and generally 

lower socioeconomic status of the nonwhite population. 

Sex and plurality. —Birth weight was influenced by both sex and plurality of the baby, as 

is shown in table 14. Among both white and nonwhite infants, boys had a higher median birth 

weight than girls. This was true for babies born 

in single and plural deliveries. Infants from plural 

deliveries had considerably lower birth weight 

than single births. This was due in part to the 

large proportion born prematurely (before 37 

weeks of gestation). 

25 
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Table 13. Percentage distribution of live births, by place of delivery and attendant: United States and each
 State, 1964


[Notestotables give.
onpageVII]

Place of delivery and attendant


Clinics, other specified 

Hospitals2 and unknown places 

Statel 

I II I I 

Other Other


rota1 Phyai- Nurse and not Total Physi- Nurse and not
 cian 1 midwife cian midwife


United States


Alabama


Alaska


Arizona


Arkansan


California


Colorado


Connecticut


Delaware


District of Columbia


Florida


Georgia


Hawaii


Idaho


Illinois


Indiana


Iowa-----------------------------------


Kanaaa


Kentucky


Louisiana


Maine


Maryland


Massachusetts


Michigan


Minnesota


Mississippi


Missouri


Montana


Nebraska


Nevada


New Hampshire
 New Jersey


New Mexico


New York


North Carolina


North Dakota
 Ohio


Oklahoma


Oregon


Pennsylvania


Rhode Island


South Carolina


South Dakota


Tennessee-----------------------------,


Texan


Utah


Vermont


Virginia


Washington


Weat Virginia


Wisconsin


Wyoming


IBY state Of Occmrence. 

specified specified


I 

Percentage distribution


95.2 92.7 — 0.1 2.4 4.8 2.9 1.5 0.3

84,0 81.7 0.2 16.0 12.2 0.5 92.6 80.8 0.0 1;:; 7.4 2.7 87.9 87.7 0.0 12.1 ;:: 83.3 79.2 0.1 ;;: 16.7 6.7 ::: 

98.4 

98.7 90.5 

98.3 

0.0 

0.0 ::2 

1.6 

1.3 

0.0 

0.1 w 98.5 91.5 0.0 7.1 1.5 0.1 99.0 97.0 0.0 2.0 1.0 0.; 0.1 

99.2 99.2 0.1 0.8 0,0 92.4 91.7 0.3 0.4 0.4 87.1 80.2 0.1 6.8 1;:$ ::; 

99.4 99.1 0.3 0.6 0.0 H 

99.4 98.3 1.1 0.6 0.0 0.4 98.5 97.0 1.5 0.0 0.9 

98.8 94.2 ;:2 99.7 99.2 0.0 0.5 ;:: 0.6 M 

85.4 85.0 0.0 0.4 14.6 0.0 0.1 93.7 93.0 0.3 1.8 0.3 96.0 94.5 M 1.4 ::: 2.1 0.1 91.1 90.4 0.6 8.9 0.6 

98.8 96.9 0.1 1.2 0.4 0.0 ‘ 

99.8 93.9 0.0 M 0.2 0.0 98.2 98.1 0.0 0.1 0.0 0.0 

99.6 98.8 0.0 0.8 i:: 0.0 0.1 

68.8 67.9 0.2 0.8 3;.: 21.5 0.6 

94.0 93.3 0.0 0.7 0.4 0.2 

99.3 97.8 0.1 1.4 0:7 0.3 0.1 

98.3 96.8 1.4 1.7 0.0 0.1 

90.2 89.1 9.8 0.2 

99.7 99.6 ::! 0.3 0.0 

97.3 96.0 O.i 2.7 0.6 0.2 

92.7 90.7 L.c ::: 7.3 1.7 0.8 

97.8 94.2 ().5 3.0 2.2 .0.3 

92.5 91.0 0.1 1.4 0.3 

91.3 91.1 0.2 H M 0.1 99.4 98.0 1.4 0.6 0.0 0.1 

93.8 93.2 O.c 0.6 6.2 0.6 0.2 98.3 97.8 0.5 0.0 0.3 

95.6 91.3 4.: i:: 0.0 0.2 

99.8 97.8 2.( 0.2 0.0 

82.7 

99.0 81.6 

98.2 

0.1 

0.1 ;:: 17.3 

1.0 

8.8 

0.4 0.9 

0.2 

92.7 91.4 0.1 1.: 1.8 0.4 88.0 87.7 0.1 0.2 J:: 3.9 0.4 

98.0 96.3 1.; 0.5 99.4 98.7 0.; ::: 0.0 

94.5 93.8 0.; 0.; 5.5 0.3 

99.3 98.6 0.; 0.7 ::: 0.1 

94.6 94.2 0.1 0.: 5.4 0.3 0.2 

99.3 

99.6 98.7 

99.1 

0.( O.f 

0.1 0.7 

0.4 

0.0 

0.0 0.0 

0.1 

2HosPital births here include ~lY thOse bj.rthaoccuring in hospitals or in institutions, but in preViOUS pub­


lication of natality statistics they include, in addition, birtha delivered by physicians in clinics.


26

---------

---------

Table 14. Median birth weight in single 

and plural deliveries, by color and sex: 

United States, 1964 

[Notes to tables given on page VII] 

Color and sex 

~ 

White 

Both sexesMale -----------

Female 

Nonwhite 

Both sexesMale -----------

Female 

Median birth weight in 

grams 

3,320 3,330 2,450


3,380 3,390 2,49o


3,260 3,270 2,400


3,130 3,140 2,290


3,180 3,200 2,320


3,070 3,090 2,250


lComPuted to nearest 10 ~rams on basis 

of exack conversion of interval limits 

from pounds and ounces. 

Age andlive-birth order.—Maternal age and 

live-birth order both were positively correlated 

with birth weight, as shownintable15.1n general, 

median birth weight increased consistently with 

age ofmother and live-birth order. 

Whether white or nonwhite,mothers lessthan 

15 years old had children with relatively low 

weight. A majority of these children were illegitimate, and both the mothers’ immaturity and 

their reluctance to seek early prenatal care 

probably were factors affecting theweight of the 

babies. 

With increasing age,however,first birthshad 

ah;gher median weight. This trendwas reversed 

for women over 30. This wastrue for both white 

and nonwhite women. There are increased risks 

of certain complications of pregnancy inprimiparae who are over 35 years of age. When the 

fetus is subjected to these complications there 

appear to be increases in stillbirths, immaturity, 

neonatal deaths, and abnormalities. 

Very close spacing of births also appears to 

be detrimental. Since wedonot have information 

on the length of time between births, this can 

only be inferred from young maternal age and high 

birth order. For white mothers 15-19 years of 

age, the highest median weight was for first 

births. For each order thereafter median weight 

decreased. For mothers who had had more than 

four children, the median weight of the latest was 

only 3,060grams. This was the lowest weight of 

any group among the white mothers. 

Close spacing of births does not appear to 

have any effect on young nonwhite women, who 

have children with very low birth “weight regardless	 of birth order. 

There are some small declines in birth weight 

with increasing maternal age after age 30 for 

some categories of lower order births. However, 

this tendency does not extend to the higher order 

births. 

Gestation. —The best method so far developed 

to estimate length of pregnancy tiom information 

on the birth certificate is to measure it from the 

beginning of the mother’s last menstrual period 

(LMP). For 1964, LMP was available on the 

certificates of only 4 of the 54 registration 

areas: Baltimore, District of Columbia, New York 

City, and California. Other States are adding this 

item to their certificates, and more accurate 

data on gestation should be available for a larger 

number of areas in the near futur~ at present, 

however, they request only the physician’s estimate of the length of pregnancy. 

A major limitation of the gestation data for 

the United States as a whole is shown by a 

tremendous concentration at 40 weeks of gestation. 

According to the table shown on p. 29, 67 percent 

of the births occurred at 40 weeks of gestation. 

This heaping is probably due to a tendency to 

look at a normal healthy baby weighing 6 to 9 

pounds and decide that it is full term and, 

therefore, 40 weeks. However, the chances that a 

baby will arrive exactIy “on time” are small. 

Two weeks in either direction is considered a 

reasonable margin of error. A comparison with 

data from LMP reporting areas supports this 

contention. These data show that only 23 percent 

27 
-----------------------

----------------------- --------------------------

-------------------------- --------------------------

-------------------------- ------- -----

-----------------------

----------------------- --------------------------

-------------------------- -------------------

--------------------------

--------------------------

-----------------------

----------------------- --------------------------

--------------------------

--------------------------

--------------------------

--------------------------

Table 15. Median birth weight, by live-birth order, color, and age of mother: United€

States, 1964€

[Notes to tables giwm.npageVII] 

II ,Live-birth order 

Color and age of mother€

First€

H I I I 1 

Total Median birth weight in grams2€

All ages 3.290 3.250 3.290 3.32C 3,330 3.340€

Under 15 years 3,050 3,050 3,010 (=) (3) (3) 

15-19 years 3,210 3,220 3,190 3,160 3,120 3;060

20-24 years 3,280 3,260 3,300 3,290 3,260 3,220

25-29 years 3,320 3,240 3,320 3,350 3,340 3,310

30-39 years 3,340 3,210 3,300 3,330 3,360 3,370

40-49 years--.---e -----z- 3,360 3,200 3,270 3,300 3,340 3,410 

White€

All ages 3,320 3,270 3,320 3,340 3,360 3,390€

Under 15 years 3,200 3,190 (3) (3) (=) (a) 

15-19 years 3,270 3,270 3,260 3,230 3,210” 3,060

20-24 years 3,310 3,280 3,330 3,330 3,310 3,300

25-29 years--.---- 3,340 3,260 3,340 3,360 3,370 3,360€

30-39 years 3,360 3,230 3,310 3,350 3,380 3,410€

40-49 years 3,390 3,220 3,280 3,310 3,360 3,450€

Nonwhite€

All ages 3,130 3,050 3,100 3,140 3,160 3,210€

Under 15 years 2,960 2,960 2>970 (=) (3) (3) 

15-19 years 3,030 3,030 3,030 3,050 3,050 3,060

20-24 years 3,110 3,070 3,110 3,130 3;150 3,130

25-29 years 3,170 3,090 3,150 3,180 3,190 3,200€

30-39 years 3,210 3,040 3,150 3,150 3,190 3,240€

40-49 years 3,240 3,030 3,170 3,160 3,180 3,270€

lIncludesnot stated live-birth order, which is not distributed.€

2COmPuted to nearest 10 grams on basis of exact conversion of interval limits from€

pounds and ounces.€

~ewer than 250 cases in age of mother and birth order.€

28€
--------

--------------

--------

-----------------------

--------------------

--

-------

-------

------- ----------

---------- -------

-------------

ofthebabieswere bornafterexactly40 weeks of


gestation.


Conz@tt?d weeks United LMP 

of gestation States areas 

All periods 100.0 100.0


Under 20 weeks----------- 0.0 0.1 

20-27 weeks-------------- 0.6 0.7 

28-31 weeks-------------- 0.8 

32-35 weeks-------------- H) 

36 weeks----------------- ::: 

37-39.weeks 17.2 3?:; 

40 weeks----------------- 67.3 23.1 

41-42 weeks-------------- 21.3 

43 weeks and over R 5.9 

The lengthof theperiodofgestationis
also


used to defineprematurity.
 Abirthis definedas


premature if it occurred afterfewer than37


weeks of gestation.
 For the UnitedStatesasa


whole,6.9percentofthebirthswereprematurein


1964.Forthe LMP areas,thecomparable
 propor-


tionwas10.4percent.


Allfurtherdiscussion
ofperiodofgestation


is based on thefourareasreporting
LMP. Data


for the other Statesand forthe UnitedStates


can be obtained
from Volume Iof Vital Statistics 

of the United States, 1964.1 ‘ 

The sexofthechilddoesnotappeartoaffect 

thelengthoftimeinatevo. ‘I’hemedianlengthof


gestation
wasabout aweeklonger forwhiteboys


andgirls(40.0and40.2weeks,respectively)
 than


fornonwhiteboysandgirls(39.2and39.3weeks).


Pluralbirthshad shorter
periodsofgestation


than singlebirthsforbothwhiteand nonwhite


deliveries,
as shown by the followingmedian


numbers ofweeks:


CO~OYof child Sin&le Plural 

White 40.1 37.8


Nonwhite 39.3 36.8


There is.normallya closerelationship
 be­


tween theperiodof gestationand the infant’s


birthweight.The medianweightateachgestation


interval
increasedthroughthe completionof42


weeks. For babiesthatwere 3 weeks or more


overduetherewas a sIight
decreaseinthemedian


weight,as shown in table16.


Table 16. Median birth weight, by color


and period of gestation: Baltimore,


California, District of Columbia, and


New York City combinect,1964


[Notes
 totables given on page VII] 

Period of


gestation Total White :g;e


Median birth weight


in grams2


All periods:


Wt


20-27 weeks 

28-31 weeks 

32-35 weeks 

36 weeks 

37-39 weeks-------
 40 weeks


41-42 weeks


43 weeks and over-


957


1,831


2,629


2.873


3;196


3,365


3,458


3,425


3,301/ 3,103


899 1,860


1,739 1,993


2,620 2,646


2,888 2,836


3,220 3,092


3,390 3,245


3,488 3;291


3,466 3,253


lThe period of gestation is measured


from the first day of the last menstrual


period. “All periods“ includes not stated


period of gestation, which is not dis­


tributed.


‘Computed to nearest 10 grams on basis


of exact conversion of interval limits


from pounds and ounces.


NOTE: Refers only to births occurring 

within the selected registration areas. 

From thepreviousdiscussion
onewouldex­


pect thatnonwhiteinfantswould weigh lessat


a given lengthof gestation
thanwhiteinfants.


This was trueonlyfor infants
born aliveafter


the35thweek of gestation.
 Nonwhitebabiesbom


earlierthan32weeks weighedconsiderablymore


thanwhitebabies .Many investigators
 haveshown


this,and some hypothesizethatthe nonwhite


fetusmatures more rapidlyattheseearlyages.


For the,LMP areas,birthscan be divided


intofourmaturitygroups,as shownbythefollow­


ingpercentages:


Birth weight 

Lengthofgestation ~mmatwre Mature 

Premature 4.4 5.9


Mature---------------- 3.7 86.0


29 

-. 
--------

-------

---------- ------------

-----------

----------- --------- ------ --------

-------

-------

Eighty-six percent of,,all newborn infants were 

mature by both criteria. For the remaining 

three groups (14.0 percent of the births) there 

are varying risks. Studies conducted in New 

York City16 and Baltimore 17 have shown that the 

highest risk of neonatal death is among babies 

with immature weight. Those who are gestationally 

mature have somewhat lower risks of death. 

The other high-risk group, babies weighing 2,501 

grams or more but having been in u.tero fewer 

than 37 weeks, have higher risks of neonatal 

death than the completely mature births. While 

these risks are higher than normal, they are 

not nearly as high as for either of the groups 

of infants weighing less than 2,501 grams. It is 

apparently more important that an infant weigh 

at least 2,501 grams than that he complete more 

than 37 weeks of gestation. 

Season of Birth 

Table 17 shows the monthly indexes of births 

in the United States since the latter half of the 

1930’s. This is the ratio of the actual number of 

births in a month to the average monthly number 

for each calendar year. Adjustments have been 

made for the varying number of days per month. 

Table 17. Monthly index of live 

[Notes to tables 

Month of 1964 1963 1962 1961 occurrence 

In 1964, as in past years, the monthly indexes showed two peaks, a minor peak in February 

and a major peak in September: Below-average 

indexes were observed for January-May and 

November and December; the intervening months, 

June-October, had above-average, indexes. The 

maximum index occurred in September (107.7) 

and	 the minimum in April (94.9). 

In the 30 years since 1935, the seasonal 

pattern of births in the United States has changed 

little. The minor peak of the bimodal distribution 

has always been in February and the major peak 

in September. The difference separating these 

peaks has widened slightly with a diminution of 

the February peak and an accentuation of the 

September peak. 

While the pattern of monthly births has been 

fairly stable, the degree of monthly fluctuation 

has tended to increase. The standard deviations 

of the monthly indexes within calendar years have 

exhibited a long-term increase, which appears to 

have ended in the 1950’s. The standard deviation 

of the monthly indexes rose from 3.6 in 1935 to 

4.8 in 1953 and has since declined to 4.0 in 1964. 

The major contributions to these trends can be 

traced to two population segments-the nonwhite 

group and persons in the South Geographic 

births: United States, 1935-64 

givenm page VII] 

— — 

1960 1955- 1950- 1945- l:;o- 1935-

59 54 49 39 

Total---- 100.0 100,0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 — 

January ;;.: 96.4 96.4 96.3 96.3 96.6 97.8 99.1 99.9 100.0 

February 98.5 98.5 98.6 98.5 98.7 99.7 100.2 101.6 102.5 

March ---------- 97:4 98.0 98.1 98.0 97.8 97.3 97.7 98.1 99.5 101.4 

April 94.9 95.0 94.9 94.8 94.7 93.9 93.2 93.5 95.7 97.3 

May 95.9 94.2 94.0 94.1 94.1 94.1 92.9 92.8 94.3 96.6 

June 100.’7 97.3 97.5 97.5 97.7 98.1 99.0 98.8 98.6 98.6 

July 105.0 103.2 103.4 103.4 103.6 104.2 104.7 103.3 103.5 104.2 

August 104.0 106,9 106.7 106.7 106.5 106.6 106.6 105.9 105.8 105.5 

September 107.7 108.6 108.7 108.7 108.6 108.4 107.7 107.0 106.3 105,3 

October 102.1 102.9 102.9 103’.0 103.2 103.1 102.8 102.8 100.8 98.7 

November 98.0 99.4 99.4 99.4 99.5 99.5 99.4 100.1’ 97.8 95.6 

December 97.0 99.6 99.6 99.5 99.4 99.3 98.5 98.1 96.5 94.4 

NOTE: Ratio of monthly daily average to calendar year daily average multiplied by 

100. 

30 
-------- -------- -------- -------

-------------------------------------------

------------------------------------------

---------------------------------------------

--------------------------------------------- ------- ------- ------- ------- -----

-------- ---------------- ---------------- ------

--- ------- ------- -----------

-------- -------- ------------------------ ----

------------------------ ---------

------------------------------------------- --------------------- --------------

------- -------------- ------- -------

Region—both of which have unusually large amounts of seasonal variation. The nonwhite group 

and the South have accounted for most of the 

change in the amount of seasonal variation. 

Details of these d#ferentials may be found in 

an earlier report. 

Ejj%ct of seasonality on birth and fertility 

rates. — Variations in the monthly incidence of 

births within the calendar year can be analyzed 

into several components: the trend-cycle (T), the 

seasonal component (S), and the irregular movements (I). The BLS Seasonal Factor Method19 is 

,used for this purpose with data for the 10-year 

period 1955-64. 

Factor (T) is approximated by a 12-month 

moving average of the observed monthly number of 

births. It is then removed by division, leaving 

(S) x (I). Fitting a smoothed curve to these residual 

components removes the randomly distributed 

factor (I), leaving (S). 

Table 18 shows the seasonal factor (S) for 

each month of 1964. These factors yield seasonally 

adjusted monthly birth rates when divided into 

the unadjusted monthly rates. The seasonally 

adjusted rates may be interpreted as those that 

would result from the elimination of the characteristic seasonal pattern of births for the 10-year 

period ending with 1964. To facilitate comparisons, the rates based on a monthly incidence of 

births are inflated to an annual basis. The trend of 

these rates suggests that the year’s decline did 

not really begin until August, before which fairly 

stable rates prevailed. 

Illegitimacy 

An estimated 275,700 illegitimate live births 

occurred in the United States in 1964. This is 

almost 7 percent of the 4,027,490 children born in 

that year. The increase of 16,300, illegitimate 

Table 18. Seasonal factors and seasonally adjusted birth rates and fertility rates, by 

month of occurrence: kited States, 1964 

[Notestotables
 given cmpage VII] 

Seasorklzs;djusted 

Month of occurrence Seasonal 

factorl 

Total -----.---


January


Febnary


March


April


May .------ --.----


June


July ..-,. .......-------


August


September -......-


October


November --.----


December ~---..-


=3==


100.0 

96.6 21.4 106.5 

98.5 21.4 106.9 

97.8 21.1 105.0 

95.0 21.1 105.1 

95.1 21.3 106.0 

97.9 21.7 108.0 

103.3 21.4 106.5 

106.7 20.5 102.1 

108.1 20.9 104.2 

102.9 20.8 103.6 

99.0 20.7 103.3 

99.2 20.5 101.9 

lBased on 1955-64 data usinz the BLS Seasonal Factor Method (1964) of the U.S. De­


partment of Labor. 

2The quotient of the unadjusted rate and the seasonal factor; monthly rates are inflated to an annual basis. 

31 
births between 1963 and 1964 follows the pattern of 

an annual increase in the number of illegitimate 

births seen in almost every year since 1938 

(the first year for which estimates of the number 

of illegitimate births were made for the entire 

country). 

All data on illegitimate births for the United 

States as a whole are based on the reports of 

illegitimacy from 34 States and the District of 

Columbia. In making estimates for the entire 

United States, the States are grouped into nine 

geographic divisions. The ratio of illegitimate 

births to total live births for the residents of 

reporting States in each division is then applied 

to all live births occurring to residents of that 

division. The sum of the estimates for the nine 

divisions is the estimate for the United States. 

These estimates are prepared for white and nonwhite births separately. 

Trends in the number of illegitimate births 

are affected by two factors: (1) changes in the 

rate of illegitimacy—that is, in the risk that an 

unmarried woman will have an illegitimate child— 

and (2) changes in the number of unmarried 

women. 

The illegitimacy rate, illegitimate births per 

1,000 unmarried women 15-44 years of age, 

measures the risk of an unmarried woman having 

an illegitimate child. In figure 9 the trend in this 

rate since 1940 is shown for all unmarried women 

of childbearing age as a group and for certain 

5-year age groups separately. 

The continuous upward trend in the illegitimacy rate for women 15-44 during most of these 

years shows that much of the increase in the 

number of illegitimate births is due to an increasing risk. Since 1957, however, there has been 

relatively little change in the rates from year to 

year. In other words, since 1957 an increasing 

number of unmarried women, rather than an 

increased risk, has accounted for the rise in the 

number of illegitimate births. 

In 1964, for example, there were 23.4 illegitimate births per 1,000 unmarried women aged 15-

44. If there had been the same number of unmarried women 15-44 years old in 1964 as in 

1960, then this rate would have produced only 

240,800 illegitimate births (12.7 percent fewer 

than there actually were). 

K J ‘#4 — //~ 

u 

+ / <~ I I I I I I I I I I I I I I I I I I I cc 1940 1945 1950 1955 1960 1965 

YEAR 

— 

Fiaure 9. Illegitimate births per i,ooo unmarried


women, by age.


(Semi logarithmic scale)


Not all women have the same risk of bearing 

an illegitimate child. For girls less than 15 years 

of age the rate was negligible in 1964 (0.6 

illegitimate births per 1,000 unmarried women 

10- 14); for those 15 to 19 years old the rate was 

16.5. Women between 20 and 34 years of age had 

rates 2% times the rates for those of 15 to 19 

years. 

The trends for these different groups of 

women have differed considerably over the past 

25 years. Women under 25 years ‘of age have 

shown relatively little change in their risk of 

bearing an illegitimate child since 1959. Older 

women, in contrast, have shown almost continuous 

increases in their rates of illegitimacy during the 

entire period since 19401 

Concern is often expressed because a large 

proportion of the illegitimate births occur to 

teenagers. Such statements often imply that they 

have a higher risk. In fact, as shown above, they 

have lower risks than older women. The reason 

that so many illegitimate children are born to 

women 15-19 years of age is that a high proportion of women in this age group are unmarried. 

32

------------------

------------------

---------------------

-------------------

-------------------

---------------------

---------------------

---------------------

---------------------

---------------

Recently this situation has been aggravated by the 

large numbers ,of children, born during the late 

1940’s, who have been entering their late teens. 

The illegitimacy ratio, illegitimate births per 

1,000 live births, is used to describe the relative 

number of babies affected rather than the number 

of women. Since it is much easier to compute 

this measure than the illegitimacy rate (because of 

difficulty in obtaining accurate estimates of unmarried women), it is more frequently used 

but is often inappropriate. 

In 1964 there were 68.5 illegitimate births 

per 1,000 live births. For white infants the ratio 

is 33.9 and for nonwhite infants 245.0. Since 

1958 the ratio has risen more rapidly for white 

births than for nonwhite. Since illegitimacy rates 

by color are not available, it is impossible to 

state whether the narrowing of the differential 

by color is due to a similar tendency for the 

rates. 

Differentials by age are similar for the two 

color groups. Babies born to the youngest groups 

of women show the highest proportion illegitimate. 

This can be accounted for by the low proportion 

of women married and having legitimate children 

at ages under 20. For women over 20, even 

though the unmarried have high rates of illegitimacy, a large proportion are married and having 

Table 19. Estimated number of illegitimate 

legitimate children. Therefore the small numbers 

of unmarried women contribute a small proportion 

of the total births (see table 19). 

The number of illegitimate births and illegitimacy ratios for each State and the. number of 

illegitimate births for certain local areas are 

shown in Vital Statistics of the United States, 

1964.1 

BIRTHS IN PuERTO RICO AND T,HE 

VIRGIN ISLANDS (U. S.) 

Rates of Birth and Natural Increase 

The ntunber of live births that occurred in 

Puerto Rico in 1964, 78,956, was the highest since 

1952; it was 2 percent higher than in 1963. The 

birth rate per 1,000 population, however, was 30.6 

in 1964, almut the same as in 1963 and the lowest 

on record. This continues the steady decline since 

1947, when the birth rate was 42.2. 

As a result of the declining birth rate, the 

rate of natural increase has also declined in 

Puerto Rico since 1947. The rate of natural 

increase is the difference between the birth rate 

and the death rate per 1,000 population. In 1947 

this rate was 30.4, which is as high as the current 

live births and ratios. . bv. color and age 

of motker: United States, 1964 

‘[Notes to tables given on page VII] 

Age of mother Total White Nonwhite ETi!EEE 

Number of	 illegitimate live Ratio per 1,000 total 

births Hve births 

All ages 275.700 114.300 161:300 68.5 33.9 245.0 

-i 

Under 15 years 5,800 1,400 4,400 742.1 523.2 856.0 

15-19 years 111,400 45,200. 66,200 190.2 101.7 468.3 

15-17 years 58,700 21,600 37,100 299.2 160.5 602.0 

18-19 years 52,700 23,600 29,100 135.3 76.2 365 ;0 

20-24 years 87,900 40,600 47,300 61.1 33.1 220.4 

25-29 years 36,400 14,300 22,100 36.1 16.5 155.0 

30-34 years 19,500 6,800 12,700 33.3 13.7 140 � 7 

35-39 years 11,100 4,400 6,700 35.8 16.9 136.2 

40 years and over 3,600 1,600 1,900 39.0 20.7 125.2 
-------- -------- ------- -------- -------- -------

---------------------------

---------------------------

-------- -------- -------- ---

---------------------------

---------------------------

birth rate. The rate of natural increase declined 

to 25.8 per 1,000 population in 1960 andto 23.4 

in 1964. 

The Virgin Islands, in contrast to Puerto 

Rico, exhibit no downward trend in amual rates 

of birth or natural increase. The trends, if any, 

are upward. In 1964 the birth rate was 43.4 

per 1,000 population, and the natural increase 

rate was 35.0, the highest rates ever recorded 

in the Virgin Islands. The trends of birth and 

natural increase rates since 1940 are shown in 

table 20 for the Virgin Islands, Puerto Rico, and 

the United States. 

In 1964 the birth rate for the Virgin Islands 

was about twice that of the United States and the 

rate for Puerto Rico about 1%times. The annual 

rates of natural increase were even further apart 

when compared with that of the United States 

(with an increase of 11.6 per 1,000 in 1964); that 

for the Virgin Islands was three times as large 

and that for Puerto Rico was two times as large. 

In relation to land area, the 1964 natural increase 

represented an increment of about 11 persons per 

mile in Puerto Rico, and less than 1 per square 

mile in the United States. . 

Season of Birth 

Like that of the United States, the monthly 

incidence of births in Puerto Rico tends to have 

a minor peak early in the year preceding the 

major peak (see fig. 10). In 1964, monthly 

indexes of births showed the minor peak occurring, 

in March in both Puerto Rico and the Virgin 

Islands rather than in’ February as in the United 

States. Major peaks occurred in September in 

Puerto Rico (114.9) and in the United States 

(107.7) and in November in the Virgin Islands 

(127.4). 

Compared with the United States, however, 

Puerto Rico and the Virgin Islands exhibit larger 

month-to-month fluctuations. The standard deviation of the indexes summarizes the amount of 

fluctuation from month to month. In 1964 the 

standard deviation was 10.1 for Puerto Rico, 

18.9 for the Virgin Islands, and 4.0 for the 

square mile in the Virgin Islands, 18 per United States.

Table 20. Rates of birth and natural 

[Notes 

Year 

1964 -------------------------------
 1963 -------------------------------
 1962 -------------------------------
 1961 --------


1960 --------


1960-641 

1955 -591 

1950-541 

1945-491 

1940-441 

lAnnual average. 

2Based on 1943-44 data. 

square 

increase: Puerto Rico, Virgin Islands, and United 

States, 1940-64 

tQ tables given on page ,VII] 

Birth rate 

Puerto Virgin United 

Rico Islands States 

30.6 43.4 21.0 

30.7 38.1 21.7 

31.1 39.4 22.4 

31.3 34.8 23.3 

32.5 36.8 23.7 

31.2 38.5 22.4 

33.7 35.2 24.6 

36.6 32.7 24.5 

41.0 33.5 23.3 

939.7 35.3 19.8 

Natural increase rate 

Puerto 

Rico 

23.4 

23.8 

24.4 

24.5 

25.8 

24.4 

26.6 

27.7 

28.8 225.4 

35.0 11.6 

28.5 12.1 

30.2 12.9 

25.3 14.0 

26.5 14.2 

29.1 13.0 

24.0 15.2 

20.5 15.0 

19.4 13.3 

17.8 9.2 

34 
---------------------

---------------------

----------------

� 

In a study of the season of birth in Puerto 

Rico from 1941 through 1961, the maximum monthly index was observed to shift from May in 

the 1941-46 period to August in the 1946-50 period 

and to September in subsequent 5- year periods .20 

The 1964 maximum also occurred in September (114.9), but it was nearly equaled by the 

October monthly index (114.3). This is part of 

the trend toward births being concentrated in the 

October-December quarter of the year in Puerto 

Rico. In previous years the index of births in 

this quarter had been average (near 100 in the 

1946-55 period) or below average (90-100 in the 

1941-45 period). There is some evidence that 

the recent high incidence of births in the final 

quarter of the year in Puerto Rico was associated 

with socioeconomic status. This is shown by the 

following tabulation of the index of births in the 

October-December quarter of 1962 according to 

the educational attainment of the mother (this 

tabulation is not available for Puerto Rico in 

1964). 

Index foy 

Oct.-Dee. 

No schooling 105 

Grades 1-4---------------------- 103 

Grades 5-8---------------------- 106 

Grades 9-11 111 

Grade 12------------------------ 116 

Grade 13 or more 107 

Illegitimate Births 

It was previously noted in this report that 

about 7 percent of the total live births occurring 

in the United States in 1964 were illegitimate. 

The percentages were higher in Puerto Rico and 

the Virgin Islands, 23.1 and 43.3 percent, respectively. The trends in these islands since 1945 

are shown in figure 11. While the percentage of 

illegitimate births steadily declined from 33 to 23 

percent in Puerto Rico during this 20-year period, 

it remained at about 50 percent in the Virgin 

Islands until the 1960’s. Recent levels are fluctuating near 40 percent in the Virgin Islands. 

Illegitimate births in Puerto Rico and the 

Virgin Islands occurred to sizable proportions of 

INDEX 

I 20 

r--.+ 

H % * : 8 

8 !10 : * 

* 

: 

United States Iw 

s 

90 +.#.* Puerto Rico 

80 

0	 J I I I I I I I I I I 

JFMAMJJA SON 

MONTH 

Figure 10. Monthly indexes of 1ive births: Puerto


Rico and the Uni ted States, 196L


(Ratio of monthly daily average to the calendar


year daily average multiplied by 100)


motliers who were living with a husband in consensual marriage, which is prevalent in Latin 

American cultures. During 1964, the percentage of 

Puerto Rican birth classified as illegitimate 

(23.1) was comprised of 18.9 percent to parents 

who were’ ‘living together” (consensually married) 

and 4.2 percent to parents who were “not living 

together. ” Comparable figures are not available 

for the Virgin Islands and the United States. 

Tabulations of the Puerto Rican classification 

were published for the first time in Vital Statistics of the United States, 1964, Volume 1,1 and 

may be compared with an unpublished tabulation 

of 1962 data, as is shown in table 21 of this report. 

Between 1962 and 1964, the percentage of 

births to consensually married parents declined 

in Puerto Rico from 20.2 to 18.9. Comparable 

35


I 
Rollo per 1,000 

midve births 

~ T 

‘0 :’ 

200 

I 00 

0 I I I I I 1111 I I 1111 I 1945 1950 1955 I %0 1965 

YEAR 

Figure Il. Illegitimacy ratios: Puerto Rico and


the Virgin Islands.


(Illegitimate births are those to unmarried or


consensually married women)


declines were not observed inthe percentageof 

births to parents “not legally married, not living 

together.’’ Thus declines intheoverall percentage 

ofillegitimate births in this 2-year period were 

attributed entirely to declines inthe.percentageof 

consensually married parents. Declines in.the 

percentage of births to consensually married 

parents were common toallagegroups ofmothers 

but were least(less thanlpercent)within agesl5-

29 (see table 21). 

Complementing these declines were increases in the percentage of births to legally 

married parents. The percentage of legitimate 

births rose from 75.7 to 76.9 percent between 

1962 and 1964. The amount ofthis increase was 

higher for older mothers (excluding ages under 

15), as shown by table 21. Moreover, the special 

1962 tabulation shows that above-average percentages of legitimate births are found in the 

upper socioeconomic strata. Where the mother 

was at least ahigh-school graduate, forexample, 

more than 90utofevery10 birthswere legitimate 

in 1962. 

It seems likely that recent increases inthe 

percentage of legitimate births in Puerto Rico 

were due largely to rising percentages ofwomen 

who were”legally married and well educated. 

36

Table 21. Percentage distribution of births by marital status of parents, 1964, and 

amount of change in distribution, 1962-64, by age of mother: Puerto Rico 

[Notes to tables giwm on page VII] 

Change from 1962

Percentage distribution, 1964 I (percentage points) 

Age of mother


All ages---


Under 15 years-


15-19 years----


20-24 years----


25-29 years----


30-34 years----


35-39 years----


40-44 years----


45-49 years----


Parents
 All


births legally


married


100.0 76.9 

100.0 50.8 

“1OO.O 69.5 

100.0 77*5 

100.0 80.3 

100 �o 78.7 

100.0 77.1 

100.0 78.9 

100.0 77.6 

I 

Parents not legally Parents not legally


married IParents married 

legally 

Living Not living married Living Not living 

together together I together together 

18.9 I 4.2 [ +1.2 / -1.3 { +0.1


23.0 26.2 +8.2 -11.0 +2.8 

23.2 7.3 +0.4 -0.8 

18.2 +3.5 -0.7 G:? 

17.0 +1.0 -0.6 -0.4 

18.2 +2.6 -2.8 +0.2 

19.5 3.5 +2.2 -2.6 +0.4 

18.8 2.4 +2.6 -2.6 +0.1 

21.4 1.0 +7.2 -6.7 -1.0 

NOTE: Excludes not stated marital status of parents and not stated age of mother.


37

lNational Center for Health Statistics: Vital Statistics of 

i% United. States, 196~,, Vol. L Public Health Service. Washington. U.S. Government Printing Office, 1966. 

2National Center for Health Statistics: Natality statistics 

analysis, United States, 1963. VitaZ and Health Statistics. 

PHS Pub. No. 1000-Series 21-No. 8. Public Health Service. 

Washington. U.S. Government Printing Office, Mar. 1966. 

3National Office of Vital Statistics: Fertility tables for 

birth cohorts of American women, by P. K. Whelpton and A. A. 

Campbell. Vital Statistics-Speciat Reports, Vol. 51, No. 1. 

Public Health Service. Washington, D. C., Jan. 1960. 

4Freedman, R., Whelpton, P. K., and Campbell, A. A.: 

Family Planning, SterMty, and Population Growth. New York. 

McGraw-Hill Book Co., 1959. 

5U .S. Bureau of the Census: Revised projections of the 

population of the United States by age and sex to 1985. CurTent Population Reports, Population Estimates, Series P-25, 

No. 329. Washington. U.S. Government Printing Office, Mar. 

10, 1966. 

6

U.S. Bureau of the Census: U.S. Census of Population, 

1960, Subject RepotVs, Women by Number of Children Ever 

Born. Final Report P C(2)- 3A. Washington. U.S. Government 

Printing Office, 1964. table 1, p. L 

7IJ.S. .Bureau of the Census: Fertility of the population, 

June 1964 and March 1962. (kment Population RepoTts, Population Characteristics, Series P-20, No. 147. Washington. 

U.S. Government Printing Office, Jan. 5, 1966. table 1, p. 12. 

8

Whelpton, P. K., Campbell, A. A., and Paterson, J. E.: 

Fe Ttizity and Family Planning in the United States. Princeton, 

N.J. Princeton University Press, 1966. p. 348. 

‘Ibid., pp. 349-350. 

10U .S. Bureau of the Census: Estimates of the population 

of States, by age, July 1, 1964. Current PoP~zation RePoTts, 

Population Estimates, S cries P-25, No. 333. Washington. U.S. 

Government Printing Office, Mar. 30, 1966. tables 1 and 2, 

pp. 6 and 7. 

00 

11U.S. Bureau of the Census: Estimates of the population 

of the largest standard metropolitan statistical areas, 1960 to 

1964. Cuwent Population RepoTts, Population Estimates, 

Series P-25, No. 330. Washington. U.S. Government Printing 

Office, Mar. 21, 1966. table A, p. 1. 

12U .S. Bureau of the Census: Fertility of the population, 

June 1964 and March 1962. CurTent Population Reports, Population Character&tics, Series P-20, No. 147. Washington,. 

U.S. Government PrintingOffice, Jan. 5, 1966. table 4, p. 16. 

131bid., table 6, p. 17. 

14Wiener, G.: Low birth weight-a high risk factor? J. A.M.A.’ 

195:35-36, Jan. 1966. 

15National Center for Health Statistics: Natality statistics analysis, United States, 1962. VitaZ and Health Statistics. PHS Pub. No. 1000-Series 21-No. 1. Public Health Service. Washington. U.S. Government Printing office, Oct. 1964. 

16Erhardt, C. L., and others: Influence of weight and gestation on perinatal and neonatal mortality by ethnic group. 

Am. J. Pu~.HeaZth 54:1841-1855, Nov. 1964. 

17Battag1ia, F. C., and others: Birth weight, gestational 

age, and pregnancy outcome, with special reference to h]gh 

birth weight-low gestational age. infants. Pediatrics 34:417-

422, Mar. 1966. 

18National Center for Health Statistics: Seasonal variation of births, United States, 1933-63. Vita? and Hea?th Statistics. PHS Pub. No. 1000-Series 21-No. 9. Public “Health 

Service. Washington. U.S. Government Printing Office, May 

1966. 

19Bureau of Labor Statistics: The B.LS Seasona2 Factor 

Method (196~). Washington, D.C. U.S. Department of Labor, 

Apr. 1964. 

20 Cowgirl, U. M.: Recent variations in the seaeon of birth 

in Puerto Rico. Proc.Natn.A.cad. Sci. U. S. A.52:1149-1159, Nov. 

1964. 

o— 

38 U. S. GOVERNMENT PRINTING OFFICE: 1967 0-243-645 
OUTLINE OF REPORT SERIES FOR VITAL AND HEALTH Statistics 

Public Health Service Publication No. 1000 

Seties 1.	 PYogYams and collection &oceduYes.- Reports which describe the general programs of the National 

Center for Health Statistics and its offices and divisions, data collection methods used, definitions, 

and other material necessary for understanding the data. 

SeTies 2.	 Data evahation and methods reseaych. —Studies of new statistical methodology including: experi- . . 

mental tests of new survey methods, studies of vital statistics collection methods, new analytical 

techniques, objective evaluations of reliability of collected data, contributions to statistical theory. 

Series 3.	 Analytical studies. -Reports presenting analytical or interpretive studies based on vital and health 

statistics, carrying the analysis further than the expository types of reports in the other series. 

Seyies 4. Docamerzts and committee YepoYts.— Final reports of major committees concerned with vital and 

health statistics, and documents such as recommended model vital registration laws and revised birth 

and death certificates. 

Series 10.	 Data jlom the Health Interview SuYvey. —Statistics on illness, accidental injuries, disability, use of 

hospital, medical, dental, and other services, and other health-related topics, based on data co~ected 

in a continuing national household interview survey. 

Sevies 11. Data porn the Health Examination Swvey. — Data from direct examination, testing, and measurement of national samples of the population provide the basis for two types of reports: (1) estimates 

of the medically defined prevalence of specific diseases in the United States and the distributions of 

the population with respect to physical, physiological, and psychological characteristics; and (2) 

analysis of relationships among the various measurements without reference to an explicit finite 

universe of persons. 

SeTies 12.	 Data from the Institutional Population Surveys. —Statistics relating to the health characteristics of 

persons in institutions, and on medical, nursing, and personal care received, based on national 

samples of establishments providing these services and samples of the residents or patients. 

Seyies 13.	 Data fYorn the Hospital DischaYge Survey. —Statistics relating to discharged patients in short-stay 

hospitals, based on a sample of patient records in a national s~Ple of hospitfls. 

Seties 20.	 Data on moYtality.—Various statistics on mortality otier than as included in amual or monthly 

reports —special analyses by cause of death, age, and other demographic variables, also geographic 

and time series analyses. 

Seyies 21.	 Data on nutality, mayyiage, anddivoyce. —Various statistics on natality, marriage, and divorce other 

than as included in annual or monthly reports— special analyses by demographic variables, also 

geographic and time series analyses, studies of fertili~. 

Series 22.	 Data jYom the National Natality and MoYtality Swveys. —Statistics on characteristics of births and 

deaths not available from the vital records, basedon sample surveys stemming from these records, 

including such topics’ as mortality by socioeconomic class, medical experience in the last year of 

life, characteristics of pregnancy, etc. 

For a list of titles of reports published in these series, write to: Office of Information and Publications 

National Center for Health Statistics 

U.S. Public Health Service 

Washington, D.C. 20201