NATIONAL CENTER Series 21 

For HEALTH “STATISTICS INumber 8 

VXTAL and XiEALTH STATISTICS 

DATA FROM THE NATIONAI-VITAL STATISTICS SYSTEM 

Natality 

Statistics 

Analysis 

United States � 1963 

Analyzes factors affecting recent trends in fertility. 

Compares the birth rates of the white and nonwhite 

populations, States, metropolitan areas, Puerto Rico, 

and the Virgin Islands. Also discusses the following 

characteristics of live births: sex ratio, plurality, 

attendant at birth, birth weight, period of gestation, 

season of birth, and legitimacy. 

Washington, D.C. March 1966 

U.S. DEPARTMENT OF 

HEALTH, EDUCATION, AND WELFARE Public Health Service 

Wi 11iam H. Sfewart John W. Gardner 

Secretary Surgeon General 
. .. ,.. 

. . . 

,,. 

Public Health Service Publication No. 1000-Series 21-No. 8 

For sale by the Superintendent of Dcwmente, U.S. Government Printing Offios 

Washington, D. C., 20402- Price 30 cents 
NATIONAL CENTER FOR HEALTH STATISTICS 

FORREST E. LINDER, PH. D., ~;?’ECkO’ 

THEODORE D. WOOLSEY, Deputy Director 

OSWALD K, SAGEN, PH.D., Z/nistant Director 

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

ALICE M. WATERHOUSE, M.D., Medica2 Advisor 

JAMES E. KELLY, D.D.s., Dental Advifor 

LOUIS R. STOLCIS, M.A., Executive Oficer 

DIVISION OF VITAL STATISTICS 

ROBERT D. GROVE, PH. D., Chief 

ANDERS S. LUNDE, PH. D., Aktant Chiej 

A~THUR A. CAMPBELL, Chief,NatalityStatirtic~ Branch 

CHARLES R. COUNCIL, Chief, Registration Methodr Branch 

. 

Public Health Service Publication No. 1000-Series 21-No. 8 

Library of Congress Catalog Card Number 6.5-62786 
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CONTENTS


Page 

Introduction 1


Recent Trends inFertiliW--------------------------:---J--------------- 1


The Long-Range Perspective 1


Trends tiTotal FertiE~-------------------------------------------- 3


The hcrease in Completed Fertili~---------------------------------- 5


~e Temporary Inflation of Total Fertility 5


The Changing Parity Distrfiution 7


Trends in Childbearing at the Younger Ages --------------------------- 8


The Role of the Contraceptive Pill 11


The Changing CMl*earing Population 13


z
 The Fertili~of__pulation Groups 13


‘Fertilityby Color 14


Fertility by States and ogra ic Divisions 14
 I&i’


Fertility by Memopoimn 1? Residence 17


Characteristics ofBirtis 17


S=Ratio 17


+kral Births 18


=endant at Birth--------=~ 18


WBilth Weight and Period of Gestation 20


Season of Birth 24


/~egitimacy 25


w 

Births in Puerto Rico and the Vir@nIslands 27


Levels and Trends 27


Health Characteristics of the Newborn Infant --------------------------- 28


References 29


III 
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CONTENTS—Con. 

Figure 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

Cumulative birth rates by exact ages, cohorts of 1875-1944 

Percent of women with specified number of births by exact age 30, January 1, l9l7-64----------_----.---_--=-------------------------

Birth rates by age of mother, l94O-63-----------------------------

Cumulative birth rates by exact ages 18-24years,cohorts ofl910-46--

Fertility ratesby color, 1920-63----------------------------------

Percent of nonwhite live births occurring in hospitals, by geographic 

division, l95O-63------------------------------------------------

Birth rates by month: observed rates, seasonally adjusted rates, and 

trend-cycle, l957-63-------------------------------------------

Illegitimacy ratios, by color, 1940-63-----------------------------

Page 

6 

9 

10 

11 

15 

20 

25 

26 

Iv 
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CONTENTS—Con. 

Table Page 

Live births, birth rates, and fertility rates: United States, 1909 -65---- 2 

2. Total fertility rates: United States, 1917-63 4 

3. Birth rates by age of mother: United States, 1940-63 8 

4.	 Birth rates by age of mother, color, and live-birth order: United States, 

l963----------Y----------------------------------------------: 16 

5.	 Birthrates for standard metropolitan statistical areas with populations 

of1,000,OOO or more by geographic region: United States, 1963------ 17 

6.	 Live births by sex and sex ratio & birth, by color and plurality: United 

Smtes, l963---------------------------------------------------- 18 

Sex ratio at birth, by live-birth order, color, and age,of mother: United 

States, l963---------------------------------------------------- 19 

8.	 Number oflive births in plural deliveries andratio of plural live births 

to total live births: United States, 1944, 1950, and 1956-63---------- 20 

9.	 Ratio of plural live births to total live births, by age of mother and 

color: United States, l963---------------------------------------- 20 

10.	 Percent distribution oflivebirths, by attendant according to geographic 

division and color: United States, l963---------------------------- 21 

11.€ Median birth weight and immature live births as percent of total live 

births, by plurality and color: United States, 1962 and 1963---------- 22 

12.	 Immature live births ,aspercentoftotal livebirths, bycolor and urbanrural residence, for metropolitan andnonmetropolitancounties: United 

States, l963---------------------------------------------------- 22 

13.	 Median birth weight, by period ofgestation, for white and Negro single 

live births: District of Columbia, California, and New York Ci~, 

l963---------------------------------------------------------- 23 

14.	 Estimated number and ratio ofillegitimate livebirths,by age ofmother 

and color: United&ates, 1963------------------------------------ 27 

15. Live births and births rates: Puerto Rico andVirgin Islands, 1940-63-- 28 

v 

., 
.

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NATALITY RATES AND RATIOS, 1963 

TOTAL NUMBER OF LIVE B1RTH8-4,098 ,020 , 

. . 

CRUDE BIRTH RATE . . . . . . . . . . . . . . . . . 21.7 PREMATURE BIRTHS (under 37 weeks ges ­

(per 1,000 population) tation) . . . . . . . . . . . . . . . . . . . . . . . . . . ...6.8 

(per 100 Iive births) 

CRUDE RATE OF NATURAL INCREASE,. . ...12.1 

(persons per 1,000 population) IMMATURE BIRTHS (2,500 grams or less), ..8.2 

(per 100 live births) 

INTRINSIC RATE OF NATURAL INCREASE . ..17.1 

(per 1,000 women aged 15-44 years) MEDIAN WEIGHT AT BIR~”. . . . . . . . . ...3.290 

(in grams) 

GROSS REPRODUCTION RATE. . . . . . . . ...1.623 

HOSPITAL DELIVERIES . . . . . . . . . . . . . ...97.4 

NET REPRODUCTION RATE . . . . . . . . . . . . 1,564 (per 100 live births) 

TOTAL FERTILITY RATE . . .. . . . . . . ...3.330.6 PLURAL DELIVERIES . . . . . . . . . . . . . . ...19.8 

(per 1,000 live births) 

GENERAL FERTILITY RATE. . . . . . . . . ...108.4 

(per 1,000 women aged 15-44 Years) SEX RATIO . . . . . . . . . . . . . . . . . . . . . . ..’1.053 

(males per 1,000 female live births) 

CUMULATIVE BIRTH RATE BY AGE OF 

WOMEN, JANUARY 1, 1964 ESTIMATED LEGITIMATE FERTILITY 

(per 1,000 women) RATE . . . . . . . . . . . . . . . . . . . . . . . . ...146.3 

15t019 years . . . . . . . . . . . . . . . . . . . ...90 (per 1,000 married women aged 15-44 years) 

20t024 years . . . . . . . . . . . . . . . . . . . ...928 . 

25t029 years . . . . . . . . . . . . . . . . . . ...2.138 ESTIMATED ILLEGITIMATE FERTILITY 

3ot034JW133..... . . . . . . . . . . . . . . ..2.77fj RATE . . . . . . . . . . . . . . . . . . . . . . . . . ..22.5 

35t039 years . . . . . . . . . . . . . . . . . . ...2.867 (per 1,000 unmarried women aged 15-44 years) 

4ot044y&31W . . . . . . . . . . . . . . . . . . ...2.794 

4.5t049 years . . . . . . . . . . . . . . . . . . ...2.463 ESTIMATED PERCENT COMPLETENESS 

50t054 years . . . . . . . . . . . . . . . . . . ...2.304 OF BIRTH REGISTRATION . . : . . . . . . . . . ; 98.9 

SYMBOLS 

Data not available 

Category not applicable . . . ,. 

Quantity zero -

Quantity more than O but less than 0.05---- 0.0 

Figure does not meet standards of 

reliability or precision * 
NOTES TO TABLES 

1.	 Alaska and Hawaii. —All tables showing time series 

include data for Alaska beginning 1959, Hawaii 1960. 

2.	 50-percent sample. — All data for the years 1951-54 

and 1956-64 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. —Age of mother, live-birth order, 

birth weight, and period of gestation data which 

were not stated in frequency tables, Vital Statistics 

OJthe United States, 1963, Volume 1, were distributed 

in proportion to the frequency of known cases in the 

preparation of rate tables, percent distributions, 

and indexes for this reprt. 

4.	 Race and CO1OVnotstated. —Data on births by color 

are not available for New Jersey for 1962 because 

this State did not ask for the race of either parent 

on a revision of its birth certificate introduced at 

the begiming of 1962. The color item was restored 

in the latter part of 1962, but the certificates without this item were used for most of 1962 and 1963. 

Therefore, all tables showing data by color for 

1962 and 1963 for the United States exclude data for 

residents of New Jersey. 

5.	 Adjustment for undervegW~ation of bivths. — Adjustment for failure to register births was discontinued 

in 1960, when it was estimated that 98.9 percent of 

all births were registered. However, table 2 makes 

allowance for both the underregistration of births 

and the underenumeration of the base population. 

6.	 Live-biyth oydey. —Live-birth order refers to the 

number of children born alive to mother. 

7.	 Attendant at bzvth. —In the United States it is assumed that all births occurring in hospitals or 

institutions are attended by physicians; in Puerto 

Rico and the Virgin Islands, a large proportion 

of hospital births are attended by persons other 

than physicians. 

8.	 ZUe@”timate bivths. — The number of illegitimate 

births for the United States as a whole is estimated 

from the numbers reported by 34 States and the 

District of Columbia. 

9.	 P@latim 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; for all other years, 

estimated as ‘of July 1. 

10.	 Wbun. —The urban population consists of inhabitants 

residing in incorporated cities of 2,500 inhabitants 

or more and in unincorporated areas of 25,000 

or more inhabitants or in those of high density as 

specified in Vital Statistics of the United States, 

1963, Volume 1, p. 4-7. 

11.	 Standard metropolitan statistical aveas. —The standard metropolitan statistical areas (SMSA’S) are 

those established by the Bureau of the Budget as of 

1960 except in the New England States. In the other 

44 States, an SMSA is a county or a group of contiguous counties which contains at least one city 

of 50,000 inhabitants or more or “twin cities” 

with a combined population of at least 50,000 in 

the 1960 census. In addition, contiguous counties 

are included in an SMSA if, according to specified 

criteria, the y are essentially metropolitan in character and socially and economically integrated with 

the central city or cities. In the New England States, 

the metropolitan State economic area (MSEA) established by the Bureau of the Census, which is made 

up of county units, is used. 

VII 
I I 

IN THIS REPOR T statistics aye presentedfov births in the United States 

in 1963 with an anulysis of these data. The repovt makes use of information obtained from microfilm copies of the original certificate of live 

bivths fyom the 50 States and the District of Columbia. 

In 1963 biyths exceeded the figure of 4 million for the tenth consecutive 

year in spite of a contiming decline in the birth vate fov the sixth consecutive year since the last peak was veached in 1957. The rates are 

still well above those observed in the peyiod immediately priov to World 

Wa~ II. 

The cuyyent decline is due, iu part, to the shift in the childbearing ages 

which occuwed in the 1950 ‘s. Because the women who are now ovey 25 

yeavs of age hud highey birth rates at youngey ages, they are now having 

loweY bivth rates at the oldey ages. CuYrent fertility declines at the 

youngey childbearing ages (undev 25 years) may be due to the postponement of man-iage and childbearing to latey ages OY to a Yeduction in the 

number of childyen couples will have. 

OtheY findings of the YepoYt include: 

Women who had completed the childbearing peyiod by 1964 (those 50 

yeavs of age) had 2.3 childven per woman. Younger women will exceed 

this figwe by a wide margin. By 1964, women aged 40 had alveady 

borne 2.8 childnw while those 30 yeays of age had borne 2.6 childyen. 

Theve isa potential foy a Yise in the annual numbev of biyths in the neav 

futuve due to the increasing size of the young childbearing population. 

In 1963, theye weve about 6.3 million women in the 20-24 yeav age group. 

By 1970, there will be approximately 8.5 million, OY an incvease of 35 

peycent. 

Differences between white and nonwhite feytility have been faivly constant in Yecent yeans. Both gYoups reached peak feytility in 1957, and 

since then have shown declines in theiy bivth Yates. 

Declines in the bi~th Yate between 1962 and 1963 occuvved in eveyy geographic division and in almost evevy State. 

Ovev 97 percent of all live biyths in the entiye United States weye delivered in hospitals. Ninety-nine peycent of all white live biyths weye 

deliveyed in hospitals; foy nonwhites the jiguve was 88 pevcent. In sev ­

eyal of the SoutheYn States ovey 20 peycent of the nonwhite biyths weye 

not attended by docto~s. 

About 8 out of eveyy 100 biyths weye classified as immat?.we, that is, 

weighing less than 2,500 gyams (5 pounds, 8 ounces). The median biyth 

weight foy all live births was 3,290 ~ams (7 pounds, 4 ounces). 

An estimated 6 peycent of all bivths were ille~”timate in 1963. Eighteen 

peycent of the biyths to women undey 20 yeavs of age weye illegitimate. 

VIII 
NATALITY STATISTICS ANALYSIS


Arthur A. Campbell, Alice Clague, Frank Godley, and Harry M. Rosenberg, Division of Vital Statistics 

INTRODUCTION 

The purpose of, this report is to present and 

interpret important features of the 1963 birth 

“statistics for the United States, which are shown 

in detail in Volume I of Vital Statistics of the 

United States, 1963, “Natality.” 

The contents of this publication are similar 

to those of its predecessor, Natality Statistics 

Anu.lysis United States, 1962 (Series 21, No. 1). 

However, the latter report deals with some topics 

not included in this report. Among these are a 

brief history of the birth registration system in 

this country, a description of the Standard Certificate of Live Birth, and an international comparison of birth rates. Readers interested in these 

subjects may wish to refer to the earlier report. 

Birth statistics for 1963 are based on information reported on the birth certificates of 

54 reporting areas in the United States, one in 

Puerto Rico, and one in the Virgin Islands. 

Registrars in these areas send copies of all 

birth certificates to the Division of Vital Statistics. 

Here, a 50-percent sample of the certificates is 

Selected. All tabulations are based on this sample. 

Data on births by color are not available for 

New Jersey in 1962 and 1963 because this State 

did not ask for the race of either parent on a 

revision of its birth certificate that was introduced at the beginning of 1962. The color item 

was restored in the latter part of 1962; however, 

certificates without this item were used for most 

of 1962 and 1963. 

Most of the statistics presented here do not 

include an adjustment for the failure 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, Vital Statistics 

of the United States, 1963, “Natality.” 

RECENT TRENDS IN FERTILITY 

Fertility in the United States reached a post-” 

war peak in 1957. In that year, there were 123 

births per 1,000 women 15-44 years of age 

(table 1). Since then, the fertility rate has declined. In 1963 it was 108, and in 1964 the rate 

was 105. At the time of this writing, the provisional rate for the first 11 months of 1965 was 

97. (This is seasonally adjusted and comparable 

to, the annual rates cited above.) In this section, 

some of the factors behind the recent decline in 

fertility are described. 

The Long-Range Perspective 

Although the fertility rate of 108 for 1963 

is low in relation to that of 123 in 1957, it is still 

well above the rates observed in the period immediately before World War II. From 1933 to 1939, 

the fertility rate varied between 76 and 79; and 

averaged 77.4. The rate for 1963 is 40 percent 

above this level. Even the rate of 97, observed 

in the first 11 months of 1965, is high in comparison with prewar levels (table 1). 

1 
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Table 1. Live birtha, birth rates, and fertilityrates: United States, 1909-65


(Notes totables given
onpageVII) 

Year Live births B&th’ratel Fertility rate 

Registered births Number Ratea per 1,000 

population 

Rates per 1,000 women aged 15-44 yeara 

:;;:2 - 19.5 96.9 

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 

1959 4,244,796 24.0 .118.8 

Births adjusted for underregistration
3


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


1958


1957


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


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


1954


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


1952


1951


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


1949


1948


1947


1946


1945


1944


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


1942


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


1940


1939


1938


1937


1936----”
 1935


1934-------------------------------------------


1933


1932-------------------------------------------


1931


1930-------------------------------------------


1929


1928


1927


1926


1925


1924


1923


l922-----------------------------------.-,-------


1921


1920


1919


1918


1917


1916-------------------------------------------


1915


1914-------------------------------------------


1913


1912


1911


1910-------------------------------------------


1909-------------------------------------------


24.3 120.2


24.5 120.2


25.3 122.9


25.2 121.2


25.0 118.5


25.3 118.1


25.1 115.2


25.1 113.9


24.9 111.5


10’6.2


24.5 107.1


24.9 107.3


26.6 113.3


24.1 10:.:


20.4


21.2 88;8


22.7 94.3


22.2 91.5


20.3 ;;.;
 19.4 .


18.8 77.6


19.2 79.1


18.7 ;;.j


18.4


18.7 77:2


19,0 78.5


18.4 76.3


19.5 81.7


20.2 84.6


21.3 89.2


21.2 89.3


22.2 93.8


23.5 99.8


24.2 102.6


25.1 106.6


26.1 110.9


26.0 110.5


26.2 111.2


28:1 119.8


27.7 117.9


26.1 111.2


28.2 119.8


28.5 121.0


29.1 123.4


29.5 125.0


29.9’ 126.6


29.5 124.7


29.8 125.8


29.9 126.3


30.1 126.8


30.0 126.8


lFor 1917-19 and 1941-46, based on population includingArmed Forces abroad. 

lSeaSonaIIY adjusted provisionalestimate for the first 11 months of 1965. 

3For lg15-32, figues include adjustments for States not in the registrationarea. For years prior to 

1915, estimates are based on the number of births registered in the 10 original registrationStates. Estimates for 1909-34 were prepared by P. K. Whelpton. See National Office of Vital Statistics:Births and 

birth rates in the entire United States, 1909 to 1948. Vital Statiatica-Special Reporta, Vol. 33> No. 8, 

1950.


2

Thus far in this report, the fertility rate has 

been used rather than the birth rate (births per 

1,000 total population), because the trend in the 

birth rate gives a different and misleading impression. In 1963, the b~th rate was 21.7 per 

1,000 population. This is only 16 percent above 

the average rate of 18.7 observed during 1933-39. 

This differential contrasts sharply with that for 

&e fertility rate. As noted in the preceding paragraph, the fertility rate for 1963 is 40 percent 

above the 1933-39 level. 

This means that the most popular measure 

of fertility, the birth rate, understates current 

fertility, relative to the prewar level, by a wide 

margin. If the ratio of the birth rate to the fertility rate had remained unchanged since 1933-39, 

the birth rate in 1963 would have been 26.2, rather 

than orily 21.7. 

The 1963 birth rate is markedly closer to 

prewar levels than is the fertility rate because 

the childbearing population (taken here as women 

15-44 years of age) is a smaller proportion of 

the total population than it was before the war. 

In the middle of the 1933-39 period (1936), the 

childbearing population constituted 24 percent of 

the total population; in 1963, the comparable 

proportion was 20 percent. As a consequence, the 

higher fertility of women in 1963 was partially 

offset by a reduction in the proportion of people 

in the childbearing population, The net result is 

a relatively low birth rate for the total population. 

The reduction in the relative size of the childbearing population is due in large part to the increase in the proportion of children in the population, which is due in turn to the higher fer ­

tility of the postwar period. In 1936, the proportion of persons under 15 years of age was 26.5 

percent. In 1963, the comparable proportion was 

31 percent. 

This shows that a substantial and sustained 

rise in fertility eventually depresses the birth 

rate in relation to the fertility rate.a 

aThe relationship between fertility and the birth rate is 

described in detail by A. J. Coale and M. Zelnik in ch. 6 of 

New Estimates of Fertitity and Population in the United States, 

Frinceton, Princeton University Press, 1963. 

Trends in Total Fertility 

For the purposes of analyzing trends in fertility, the “total fertility rate” is more useful 

than the fertility rate (births per 1“,000 women 

15-44 years) referred to in the preceding discussion. The total fertility rate is the sum of the 

age-specific birth rates for singIe years of age 

for all ages in the reproductive span. (See footnote on table 2 for definition and qualifications.) 

It is an age-adjusted rate because it is based on 

the assumption that there are the same number . 

of women at each single year of age. 

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 age-specific birth rates 

throughout the reproductive age span. The rate 

of 3,331 for 1963, for example, means that if a 

hypothetical group of 1,000 women were to have 

the same birth rates at each single year of age 

that were observed in the entire childbearing pop- , 

ulation in 1963, they would have a total of 3,331 

children by the time they reached the end of the 

reproductive period (taken here as age 50), assuming that all survive to that age. 

This rate is useful because it can be compared with the projected childbearing of actual 

groups of women as they proceed through the 

reproductive period of life. Such comparisons 

give some idea of the extent to which fertility in 

a given year may be distorted by factors that may 

have only a temporary effect. For example, the 

total fertility rate for 1957 was 3,724. This was 

the highest rate observed b this country since the 

beginning of the series in 1917 (table 2). However, 

there was evidence from a 1955 interview survey 

of married women that no actual group of women 

then in the childbearing population expected to 

have as many as 3,700 children per 1,000 women 

by the end of the reproductive period. b This 

meant that the 1957 rate of 3,724 was “inflated” 

bSee projected cumulative birth rates for ages 45-49 in 

table 10-7, Family Planning, Sterility, and Population Growth, 

by R. Freedman, P. K. Whelpton, and A. A. Campbell, New 

York, McGraw-Hill Book Co., 1959. 

207-0440-66-2 
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Table 2. Total fertility rates: United States, 1917-63


(Notes to tables given on page VII) 

Rates per
 Year 1,000 women Year


1963------------------------ 3,331 1939-----------------------

1962------------------------ 3,476 1938-----------------------

1961------------------------ 3>620 1937-------” 

1960------------------------ 3,655 1936-----------------------

1959------------------------ 3,669 1935-----------------------

1958------------------------ 3,654 1934-----------------------

1957------------------------ 3,724 1933-----------------------

1956------------------------ 3,634 1932-----------------------

1955------------------------ 3,521 1931-----------------------

1954------------------------ 3,501 1930-----------------------

1953------------------------ 3,378 1929-----------------------

1952------------------------ 3,307 1928-----------------------

1951------------------------ 3,209 1927-----------------------

1950------------------------ 38030 1926-----------------------

1949------------------------ 3>030 1925-----------------------

1948------------------------ 3,013 1924-----------------------

1947------------------------ 3,158 1923-----------------------

1946------------------------ 2,829 1922-----------------------

1945------------------------ 2,392 1921-----------------------

1944------------------------ 2,466 1920-----------------------

1943------------------------ 2,616 1919-----------------------

1942------------------------ 2,532 1918-----------------------

1941------------------------ 2,314 1917-----------------------

1940------------------------ 2,214 

Rates per


1,000 women


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 underregistration for all years (including 1960-63) and on population estimates adjusted for underenumeration. Hence, they are not precisely comparable to the birth rates and fertility rates shown .intable 1. For the method of adjusting the population bases, see the Methodological Appendix in National Office of Vital Statistics: Fertility tables, 

for birth cohorts of American Women,pt. 1, by P. K. Whelpton and A. A. Campbell, Vital 

Statistics-Special Reports, Vol. 51, NO. 1, 1960. 

in the sensethatsuch a highratecouldnotbe


maintainedfora longtime.Thetotal fertility
 rate


wouldsoonhavetodescendtoalevelwhichwould


be more compatible
withtheexperienceofactual


groupsof women living
throughthechildbearing


period.


The recentdeclineofthetotalfertility
 rate


tovaluesintherangeof3,000-3,300 (therate
for


1963 was 3,331,butratesfor1964and1965 will


be somewhat lower)represent;in part,an in-”


evitable declinefrom theinflated
 levelsof3,,500-


3,700 observed throughoutthe periodbetween,


1954 and 1962.The totalfertility
 ratehad been


distorted
upward for at least9years,andcould


no longerremain at such highlevels,
giventhe


averagecouple’s desireforfamilies
ofmoderate


size.


4 
The Increase in Completed Fertility 

Not all of the postwar rise in fertility can be 

properly interpreted as inflation, however. Most 

of the rise in the total fertility rate from the lows 

of 2,100-2,200 observed during 1933-39 to the 

postwar range of 3,000-3,700 was due to a real 

increase in the average number of children that 

couples had (sometimes called “average size of 

family”). This concept is best measured by the 

“completed fertility rate, ” which is the average 

number of births (per 1,000 women) that a group 

of women has by the end of the childbearing 

period (assumed to be age 50). The groups of 

women referred to are called “cohorts, ” and are 

identified by the year of their birth so that they 

always carry the same designation, regardless of 

their age.c Thus, it is possible to make statements about the 1920 cohort when its members 

were 30 years old in 1950 and when they were 40 

years old in 1960—referring to the same group 

of women in both years. 

The long-term decline in the completed fertility of cohorts, as well as the subsequent upturn, is shown in figure 1. The low was reached 

by the 1909 cohort, which averaged 2,230 births 

per 1,000 women. Later cohorts have had successively higher rates. The most recent cohort 

to reach age 50 by the end of 1963 (the 1914 cohort) had 2,334 births per 1,000 women. 

Although later cohorts have not yet reached 

age 50, it can be predicted that their completed 

fertility will surpass that of the 1914 cohort because they have already borne more children by 

younger ages. In order to see how many births 

women have had before the end of the childbearing 

period, “cumulative fertility rates” are used. 

The cumulative fertility rate by age 40 for the 

1924 cohort (which describes the number of births 

this cohort had by the end of 1963) was 2,835 

cThe 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 stated on pages 106-108 in National Office for Vital Statisti CS, “Fertility Tables for Birth 

Cohorts of American Women,” Pt. 1, by P. K. Whelpton and 

A. A. Campbell, Vitat Statistics–Special Reports, Vol. 51, 

No. 1, Public Health Service, Washington, D. C., 1960. 

births per 1,000 women. This exceeds by a wide 

margin the. completed fertility of the 1914 cohort. 

It is not yet known 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 3,100-3,500 births 

per 1,000 women.d By the end of 1963, when they 

were 29-33 years old, the women in these cohorts 

had borne 2,700 children. 

Projections for later cohorts are, of course, 

even more speculative. The Scripps Foundation 

projections show “a range of 2,900-3,400 for the 

1936-40 cohorts and 2,700-3,400 for the 1941-45 

cohorts. The Census Bureau’s projections for 

these groups are slightly higher, however, with 

estimates for the 1936-40 and 1941-45 cohorts 

being 3,200-3,500 and 3,000-3,500, respectively. 

The 1941-45 cohorts had reached the ages of 

19-23 years by the end of 1963, and had borne 

slightly under 700 births per 1,000 women, so it 

is difficult to foresee how many children they 

will have altogether. 

Although precise estimates cannot be made 

of the number of children young women will have 

by the end of the childbearing period, it does not 

now seem likely that their completed fertility 

rates will exceed 3,400. Therefore, any total 

fertility rates for calendar years that exceed this 

level may be considered inflated. 

The Temporary Inflation of Total Fertility 

What brought about the upward distortion of 

total fertility rates in the 1950 ‘s? The answer 

‘These projections were prepared by the Scripps Foundation for Research in Population Problems, Miami University, 

Oxford, Ohio. . They are reported in Fe~tility and Fami2y Planning in the United States, by P- K. Whelpton, A. A. Campbell, 

and J. E. Patterson, Princeton, Princeton University Press, 

1966. The projections of the U.S. Bureau of the Census for 

these cohorts lie in the narrower range of 3,3oo to 3,5oo; see 

“Projections of the Population of the United States, by Age 

and Sex, 1964 to 1985, ” by J. S. Siegel, M. Zitter, and D. S. 

Akers, Current Population Reports, Series P-25, No. 286, July 

1964. The Scripps Foundation’s projections are cited in the 

text of the present report because their wider range is somewhat more cons ervative. 
4,000 

( 

3,500 

3,000, 

z 

w 

z 

!2 

0 

0 

:- 2,000 

m 

u 

a 

m 

w 

~ 

a 

1,500 

1,000 

500 

20 

0 

1875 1880 1885 1890 1895 I900 1905 1910 1915 1920 1925 1930 1935 1940 I945 

GOHORT 

Figure 1. Cumulative birth rates by exact ages, cohorts u’f IB75-19$L}. 

(Rates based on births adjusted for underregistration for all years, including 1960-63, and on population estimates adjusted for underenumeration) 6 
lies in certain shifts in the timing of b&.hs. Two 

broad changes were underway. 

First, the cohorts of 1916-25 (approximately) 

had higher birth rates at the older childbearing 

ages than the cohorts preceding them. The 

members of these cohorts reached the early ages 

of childbearing during the 1930’s and early 1940’s, 

when economic conditions and war may have made 

it advisable or necessary to postpone marriage 

and childbearing. By 1950, the women in these 

cohorts were 25-34 years old, and they were 

having children at the highest rates observed 

since the cohorts of the 1890’s. By 1960, they 

were 35-44 years old, and the inflationary y effect 

of their higher fertility on the total fertility rate 

had virtually run its course. 

A second and more important shift 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 old 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. 

The effects of this shift toward earlier childbearing had begun to diminish in the early 1960’s. 

In brief, the inflationary effects of two shifts 

in timing patterns overlapped, and birth rates 

were high in the 1950’s at all ages of childbearing, 

both young and old (table 3). 

The fact that fertility is declining at the 

older ages of childbearing (ages 25 and over, 

approximately) was a foreseeable consequence 

of the concentration of births into the early years 

of the childbearing period. The following prediction was published in 1959: 

When all the postponed births are made up, 

and the tendency to marry and have the first 

birth at progressively younger ages stops, 

age-specific birth rates will decline and the 

crest of the wave will have passed. This may 

occur even though the average size of completed families becomes substantially larger 

than it is now.l 

The decline in birth rates was projected for 

the early 1960’s. This expectation has since been 

fully confirmed. 

The Changing Parity Distribution 

The effect of younger childbearing is to increase the proportion of women who have all the 

children they want by a given age. This is illustrated by figure 2, which shows the proportion 

of women who have had various numbers of children by the age of 30. The proportion who have 

had three or more children has doubled in 20 

years (three is chosen because it is close to the 

average number of children that married couples 

want and expect). This shift toward more children 

has greatly reduced the proportion of childless 

and one-child women, and since 1955 has also 

brought down the proportion of women with only 

two children. 

Between January 1, 1957, and January 1, 

1964, the proportion of 30-year-old women with 

three or more children rose from 36 to 49 percent. This means that the proportion with fewer 

than three children by the same” age dropped 

from 64 to 51 percent. Because most of the women who want additional births are among those 

with fewer than three children, the reduction in 

this proportion has also brought about a reduction 

in birth rates after the age of 30. 

A report prepared by the Population Studies 

Center of the University of Michigan supports 

this explanation.2 By comparing the past and 

expected future childbearing of white women interviewed in surveys between 1955 and 1963, this 

study shows that the proportion of total expected 

children already born by ages 25-29 had risen 

born 62 percent in 1955 to 72 percent in 1963. 

This means that the proportion of children yet 

to be borne by women in this age group declined 

from 38 percent in 1955 to 28 percent in 1963. 

At ages 30-34, the proportion of children to be 

born in the future dropped horn 22 percent in 

1955 to 13 percent in 1963; at ages 35-39, the 

comparable proportion dropped from 11 to 3 

percent. These data describe the essential reasons for the recent decline infertility at the older 

childbearing ages. 

7 
Table 3. Birth rates by age of mother: Uriited States, 1940-63 

(Notes to tables given on page VII) 

Age of mother 

Year 

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

years years years years yeara years years years 1 

Registered births Rates per 1,000 women 

1963------------------------ 0.9 76.5 231.3 185.4 105.9 51.2 14.2 

1962------------------------ 0.8 81.3 243.8 191.3 108.7 52.6 14.8 ::; 

1961------------------------ 88.0 253.6 197.8 113.3 55.6 15.6 0.9 

1960------------------------ ::: 89.1 258.1 197.4 112.7 56.2 15.5 

1959------------------------ 0.9 89.1 257.5 198.6 114.4 57.3 15.3 ‘::; 

Births adjusted for 

underregistration 

1959------------------------ 0.9 90.4 260.1 200.5 115.6 58.2 15.5 

1958------------------------ 0.9 91.4 258.2 198.3 116.2 58.3 15.7 ;;; 

1957------------------------ 1.0 96.3 260.6 199.4 118.9 59.9 16.3 ,1.1 

1956------------------------ 94.6 253.7 194.7 117.3 59.3 16.3 1.0 

1955------------------------ M 90.5 242.0 190.5 116.2 58.7 16.1 1.0 

1954------------------------ 0.9 90.6 236.2 188.4 116.9 57.9 16.2 1.0 

1953------------------------ 88.2 224.6 184.1 113.4 56.6 15.8 1.0 

1952------------------------ ::: 86.1 217.6 182.0 112.6 55.8 15.5 1.3 

1951------------------------ 0.9 87.6 211.6 175.3 107.9 54.1 15.4 1.1 

1950------------------------ 1.0 81.6 196.6 166.1 103.7 52;9 15.1 1.2 

1949------------------------ 1.0 83.4 200.1 165.4 102.1 53.5 15.3 1.3 

1948------------------------ 81.8 200.3 163.4 103.7 54.5 15.7 1.3 

1947------------------------ ::: 79.3 209.7 176.0 111.9 58.9 16.6 1.4 

1946------------------------ 0.7 59.3 181.8 161.2 108.9 “58.7 16.5 1.5 

1945------------------------ 0.8 51.1 138.9 132.2 100.2 56.9 16.6 1.6 

1944------------------------ 0.8 54.3 151.8 136.5 98.1 54.6 16.1 1.4 

1943------------------------ 0.8 61,7 164.0 147.8 99.5 52.8 15.7 1.5 

1942------------------------ 61.1 165.,1 142.7 91.8 47.9 14.7 1.6 

1941------------------------ H 56.9 145.4 128.7 85.3 46.1 15.0 1.7 

1940------------------------ 0.7 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. 

Trends in Childbearing at the by the age-specific birth rates in figure 3.One 

Younger Ages or both of two tendencies could account for this 

trend. 

The explanation offered in the preceding 

sections accounts only for the decline in fertility 1. Thepostponement ofbi~thstolatevages.— 

at the older childbearing ages. Fertility had also Perhaps today’s youngcouplesare shifting 

fallen at the younger childbearing ages (under25 their childbearing to somewhat later ages 

years of age) between 1957 and 1963, as is shown than the cohorts immediately preceding 

8 
COHORT 

PERCENT 1890 1900 1910 1920 1930


40


20


10


a 

6


4


2


I


1917 1920 1930 1940 1950 1960 1970


YEAR ATTAINED AGE 30


Figure 2. Percent of women with specified number of births by exact age 30, January i, 19[7-64.


(Logarithmic scale) 9

1

,7., 1(.-..-:-”0--= “ , ,+ .~f , .-/ II 

/:40 LLIILid 1945 1950 1955 1960 196!

Figure 3. Birth rates by age of mother, 1940-63. 

@Be:::i~fve in~irth51959 trend lines are based on reg­

; trend lines for 1940-59 are 

based on live births adjusted for underregistration. Logarithmic scale) 

them. This would amount toa reversalof 

the trend toward earlier childbearing. 

2. Sma.Uer Families. —Perhapsyoung couples 

will have fewer children altogether than 

the couples who began their families 

earlier in the postwar period. 

At the present time, there isno reason for 

preferring either explanation to the exclusionof 

the other. Both are probably correctto alimited 

extent. 

We can be reasonably certain that young 

couples now are delaying births to a greater extent than formerly because much of the 1957-63 

decline in birth rates under 25years ofage was 

for first births. Between 1957 and 1963, theportion of the total fertility rate occurring at ages 

under 25 dropped from l,780tol,553, orby227 

births per 1,000 women. (These rates are sums 

of single-year age-specific rates at ages 14-24. 

They are additive components of the total fertility rates, which were 3,724and3 ,331 for 1957 

and 1963, respectively.) Mor”e than half of this 

decline is a drop in the rate for first births. 

Assuming that couples will wish to av~id childlessness in the future, as they have in the recent 

past, most of these “deficit” births will be made 

up at later ages. 

Whether young couples will have fewer children altogether than the cohorts preceding them 

in childbearing is less certain. By the end of 1963, 

the 1940-44 cohorts (who were then 20-24 years 

of age) had borne 928 children per 1,000 women, 

so they have most of their childbearing still ahead of them. It is possible that they will exceed 

the completed fertility rates of the cohorts of the 

1930’s; which are expected to be between 2,900 

and 3,400. So far, the 1940-44 cohorts have had 

more births by ages 20-24 than the 1930-34 cohorts had by the same ages, but slightly fewer 

than the 1935-39 cohort,s. 

Cumulative rates for the cohorts of 1910 

and later, by single years of age up to age 24, are 

shown in figure 4. This detailed picture clearly 

shows the recent downward trend in the number 

of children borne by young women, but it also 

shows that cumulative rates at these ages are 

still high, relative to rates observed for the 

cohorts of 1910-29. 

Although the final outcome of the familybuilding process in cohorts who are now young is 

not certain, some information on the childbearing 

expectations of young couples is available. The 

report by the Population Studies Center of the 

University of Michigan, referred to in the preceding section; shows a small decline in the total 

number of chil@en expected by the cohorts of 

1931-35, in comparison with the cohorts of 1934-

38 .e There is no definite trend in the final number 

of births expected by later cohorts, however. 

‘f3aeed on a comparisonof an average of 3.4 births expected by married women who were 25-29 years old in 1960 

(1931-35 cohorts) with an average of 3.2 expected for married 

women of the same age in 1963 (1934-38 cohorts) shown in 

table 3 of “Current Fertility Expectations of Married Couples 

in the United States, 1963,” by R. Freedman, D. Goldberg, 

and L. Bumpass, Poprd. Index, Vol. 31, No. 1, Jan. 19~5.” 

10 
2000


EXACT AGE 

1000 

800


cc 

w 

L 

In 200
 w


i­


<


E


[00 

80


80~ 

1910 1920 1930 1940 195( 

COHORT 

Figure k Cumulative birth rates by exact aaes 

18-2q years, cohorts of 1910-i6. -

(Rates based on births adjusted for underregistration for all years, including 1960-63, and 

on population estimates adjusted for underenumeration. Logarithmic scale) 

This research into childbearing expectations 

revealed a significant trendinthetiming ofbirths: 

the more recent cohorts expect to have their 

births at later ages than did earlier cohorts.This 

finding is, of course, consistent with the interpretation of recent cohort fertility rates offered 

earlier in this section. However, itdoes not rule 

out the possibility that completed fertility will 

fall. In fact, the authors state, 

It is possible that postponement of births may 

be a first step toward revising expectations 

downward. We have some evidence that expectations are revised downward rather 

quickly as tin-+e lapses without a pregnancy. 

Only future experience will tell whether the 

cohorts now apparently postponing births will 

make them up later or will revise their expectations and fertility downward.3 

In summary, it appears that the reduction of 

birth rates at ages under 25 years is due in part 

to the postponement of births to later ages. This 

trend may also foreshadow a decline in completed 

fertility. 

The fut&e course of fertility in the United 

States depends largely upon whether completed 

fertility remains constant or falls. At the present 

time, there is no evidence that any cohorts now 

in the younger childbearing ages will begin a 

trend ,toward higher completed fertility. If completed fertility stays close to 3,000 births per 

1,000 women, then the declines that are now going 

on at the younger ages will eventually be made 

up at the older ages. However; if completed fertility falls 10 to 20 percent below this level, agespecific birth rates will continue to fall for 

several more years. 

The Role of the Contraceptive Pill 

There has been some speculation that the 

current decline in fertility has been brought about 

by the increasing use of highly effective contraceptive pills. It is impossible to tell with any 

degree of certainty what effect the “pill” has had, 

but there are certain considerations that must be 

taken into account in arriving at an informed 

opinion concerning its impact on the birth rate. 

The piII was not permitted to be used as a 

contraceptive until June 1960, and probably did 

not come into wide use until a year or more 

later. This means that if it has had any major 

influence on the birth rate, it would not be detectable until 1962, at the earliest, when children 

conceived in 1961 were born. The decline in fertility, however, started in 1958, so it was not 

possible for the pill to have initiated the downward trend or to have conmibuted to its early 

progress.. 

The number of women using the pill is not 

accurately known. The following estimates are 

based on pharmaceutical company records: 4 

1961 ----------------------- 500,000 

1962 ----------------------- 1,370,000 

1963 ----------------------- 2,280,000 

11

Informed guesses for later years have varied 

between 3 and 4 million. f At present, it is impossible to verify any of these estimates with 

data from a sample of women of reproductive 

age. 

The estimate of 2.3 million for 1963 represents 6 percent of all women in the reproductive 

period of life (taken here as 15-44 years of age). 

It is more appropriate, however, to relate the 

number of “pill users” to the population most 

subject to the risk of childbearing. For present 

purposes, this may be approximately defined as 

married women 18 to 39 years of age, living with 

their husbands (or with husband temporarily absent in the Armed Forces), who are capable of 

conceiving and bearing children. The number of 

such women in 1963 is estimated to have been 

13 million.g If it is assumed that all of the 2.3 

million pill users are in this group, which is 

probably an exaggeration, then 17 percent of the 

wornen in the high-risk group were using the pill 

in 1963. If 3.5 million women were using the pill 

in 1964, the comparable proportion would be 26 

percent. 

If a further assumption is made that the pill 

users ordinarily contribute approximately 20 

percent of the annual number of births, then a 

10-percent reduction in their fertility, due solely 

to the use of the pill, would account for a 2.0-percent reduction in total births. In other words, 

any reduction in fertility brought about by the 

use of the pill would have to be multiplied by 

a relatively small factor (it would be 0.2 in the 

example given) in order to estimate the effect 

on total births. Even if the factor of 0.2, used in 

this example, were a gross understatement, the 

decline in the fertility of pill users would have 

‘3,000,000 (Time, Mar. 31,1964, p. 39) More than 3,000,000 

by the end of 1964 (Chemicat Week, Apr. 4, 1964, p. 22) 

3,500,000 (Newsweek, July 6, 1964, p. 55) Nearly 4,000,000 

(Chicago Tribune, June 27, 1965, sec. l-A, p. 1) 

gBased on data reported in ch. 4 of Fe@ility and Family 

Planning in the United States, by P. K. Whelptcm, A. A. Campbell, and J. E. Patterson, Princeton, Princeton University 

Press, 1966. 

to be modified by a considerable amount to 

estimate the effect on all births. If a factor 

of 0.3 were more accurate, then a 10-percent 

reduction among pill users would affect all births 

by only 3 percent. 

Between 1957 and 1963, the total fertility 

rate dropped by 11 percent. By 1964, the cumulative decline from the 1957 peak was about 14 

percent, and by 1965 it was about 20 percent. 

Even if a generous allowance were made for 

the amount of the overall decline that might be 

attributed solely to the use of the pill, it would 

probably not exceed half of the decline that has 

taken place. 

Another consideration is the fact that fertility is still high, relative to levels prevailing 

during the period 1933-39. With the methods of 

control then in use, couples were able to maintain the total fertility rate within the narrow 

range between 2,100 and 2,200. The comparable 

rate for 1963 is 3,331. In other words, couples 

could have achieved levels of fertility observed 

recently without using methods of control that 

were more effective than those available 30 years 

ago. Therefore, it would be difficult, and perhaps impossible, to prove that the increased use 

of the pill has caused a substantial reduction in 

fertility that would not otherwise have taken place. 

However, there is a plausible reason for 

believing that the pill has had some independent 

effect. The incidence of unintended pregnancies 

may be regarded as a function of three variables: 

the’ strength of couples’ desire to prevent pregnancy, the effectiveness of the methods they use, 

and the convenience (or acceptability) of the 

methods. The pill is more effective than other 

methods in common use, and is generally regarded as more convenient. Therefore, the substitution of the pill for other methods of family 

limitation would reduce the incidence of unintended conceptions without any necessary increase in the strength of the couples’ motivation 

to prevent pregnancy. 

Inasmuch as many unintended conceptions 

are simply conceptions that occur somewhat 

sooner than they are wanted, we may also specu -

12 
late that one of the pill’s major effects may be 

to help couples delay biqhs for longer periods 

of time. If so, part of the recent shift toward 

later childbearing may be aided by widespread 

use of the pill. 

In addition, the pill is undoubtedly helping 

some couples avoid unwanted conceptions —that 

is, conceptions that occur when the couple does 

not want to have any more children. Whether or 

not this has much effect on the total fertility rate 

is impossible to determine at the present time. 

In summary, one can be certain that the recent decline in fertility was not initiated by the 

introduction of the contraceptive pill. To a considerable extent, the decline 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, may 

have been aided by the use of the pill, but there 

is no evidence that these changes would not have 

occurred without the pill. 

Without careful research into the childbearing 

plans and contraceptive practices of a representative sample of couples, it will be impossible 

to estimate the contraceptive pill’s independent 

effect on recent trends in fertility. 

The Changing Childbearing Population 

The only factor influencing future births 

about which one can be reasonably certain is the 

size of the childbearing population, which will 

continue to grow for many years. A significant 

portion of this rise will occur between 1965 and 

1970, when the number of women in the prime 

reproductive ages of 20-24 years will rise flom 

6.8 to 8.5 million. 

The growth of the childbearing population 

will have no effect on birth rates at each age, 

but it will influence the number of children born 

annually and the birth rate of the total population. 

The influence of changes in the childbearing 

population on the annual number of births up to 

1985 has been computed by the U.S. Bureau of the 

Census. Their investigators multiplied average 

age-specific birth rates for 1960-63 by the projected age distribution of women for each year 

from 1963 to 1985. h These calculations show that 

if fertility rates were to remain constant, the 

annual number of births would rise by about 3 

percent a year until 1975, and by about 2 percent 

a year thereafter. 

If age-specific birth rates remain constant 

between 1965 and 1970, the amual number of 

births will rise by about 16 percent. However, if 

age-specific birth rates fall by an average of 14 

percent in this period, which would be sufficient 

to overcome the influence of greater numbers 

of women, the annual number of births will remain approximately stable. If age-specific birth 

rates fall by more than 14 percent in this period, 

then the annual number of births will also fall. 

Inasmuch as the projections of the Bureau 

of the Census show that with constant fertility 

the annual number of births will rise more 

rapidly than the total population, it also shows 

that the birth rate for the total population will 

rise if fertility does not fall. The upward influence 

on the birth rate, however, amounts to only 1.4 

percent per year between 1965 and 1970, or 7 

percent over the entire 5-year period. 

In summary, there is a potentiaI for a rise 

in the annual number of births and the birth rate 

in the near future. Declining age-specific birth 

rates, however, couId counterbalance the influence of rising numbers of women in the childbearing period. The annual number of births or 

the birth rate may begin to rise in the latter half 

of the 1960’s; however this is by no means cer ­

tain. 

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. Certain 

groups have higher fertility than others while 

‘The figures refereed to ace the Series Y projections shown 

in table C-1 in U.S. Bureau of the Census, “Projections of the 

Population of the United States, by Age and Sex, 1964 to 

1985,” by J. S. Siegel, M. Zitter, and D. S. Akers, Current 

Population Reports, Series P-25, No. 286, July 1964. 

13 
some are experiencing greater declines in fertility than others. In this section of the report, 

attention will be directed toward the. fertility of 

certain major population groups. 

The kinds of groups available forcomparative analysis are necessarily limited by the information collected on birth certificates. Consequently, analysis 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 

certificate 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 will compare fertility in the white and 

nonwhite populations; the succeeding section will 

present data for States, geographic divisions, and 

certain metropolitan areas. 

Fertility by Color 

Although fertility rates for the nonwhite population were about 40 percent higher than those 

for the white population in 1963, they have followed 

the tendencies of the white population rates since 

1950 (fig. 5). Both groups reached peak fertility 

in the same year, 1957, and since then both have 

shown declines in their birth rates. 

Although recent trends in the fertility of the 

white and nonwhite populations have been similar, 

this has not always been the case. In the early 

postwar period, fertility rose more rapidly for 

nonwhite persons so that the relative excess of 

their fertility rates over those of the white population has grown. Between 1954 and 1963, the 

difference between white and nonwhite fertility 

was greater than it had been during the 1920’s 

and 1930’s. 

Color differences in fertility vary with the 

age of the mother. Although birth rates for nonwhite women excee,d those for white women at 

all ages, the relative differences are least amohg 

those age groups where birth rates are highest, 

that is, among women aged 20-24 and 25-29 years 

(table 4). For these age groups, nonwhite fertility 

exceeded white fertility by 24 percent and 17 

percent, respectively, in 1963. The differences 

were greater among both younger and older 

women, tracing a U-shaped pattern over age. 

In 1963, the birth rates of nonwhite women aged 

15-19 years were about twice those of white 

women; while among women aged 40-44 years, 

they were approximately 60 percent higher. 

The relative excess of nonwhite over white 

rates also varies with the order’ of birth. It is 

least for the lower birth orders and greatest for 

the higher, although there are some irregularities among the lower orders (table 4). Agespecific rates for fifth and higher order births 

(combined) are almost three times as high ,for 

nonwhite as for white women. 

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 Divisions 

The continuing decline of the birth rate in the 

United States was reflected in every geographic 

division and in all but three States between 1962 

and 1963. Only Connecticut, Mar yland, and Nevada 

failed to have lower birth rates in 1963”than in 

1962. By geographic division, the largest decline 

in the birth rate (6 percent) occurred in the 

Mountain Division, which also had the highest 

rate in 1963 (23.6 births per 1,000 population). 

The bir~ rate diminished least, by 2 percent, 

where it was lowest (19.9), in the Middle Atlantic 

Division. 

As a consequence of this pattern of change 

over a period of years, birth rates among the 

States have tended to converge. The convergence 

14

t 

\ 

P White 

70 L -1- J_ 

oL- T 1- 1 

1920 1930 1940 1950 1960 [970 

Figure 5. Fertility rates by color, 1920-63. 

(Rates	 per 1,000 women aged 15-44 years, Beginning in 1959 trend lines are based on registered live 

births; trend lines for 1920-59 are based on live births adjusted for underregistration) 

can remeasured bythe ’’coefficient ofvariation”- Because the birth rate is affected bychanges 

the standard deviation of the States’ birthrates in the age and sex composition ofthe population, 

from the mean as a percentage of the mean. as discussed earlier, it is not possible to deIn 1963, the coefficient of variation of State termine whether the converging rates among the 

birth rates was 9.5 percent compared with 15.6 States are due to “real” changes in fertility.. . as 

percent in 1940. For 1960, 1961~and 1962, the measured by the total fertility rate, or whether 

coefficients were 10.1, 9.8, and 9.3 percent, they merely reflect changes in the composition 

respectively. of the population associated with migration. 
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Table 4. Birth rates by age of mother, color, and live-birth order: United States,


1963


(Notes to tables given on page VII) 

I Age of mother 

Color and 15-441—


live-birth orders 

years 10-14 15-19


years years
 m
 I 1 

Rates per 1,000 women


Total 108.4 0.9 76.5 231.3 185.4 105.9 51.2 14.2 0.9 — — — — — — 

First child 29.9 0.8 53.7 82.0 24.3 7.2 2.6 0.6 0.0 

Second child 26.1 0.0 17.7 77.5 43.7 14.5 5.1 1.1 0.1 

Third child 19.9 0.0 4.2 43.1’ 46.7 22.2 8.2 1.8 0.1 

Fourth child 13.1 0.0 0.8 18.5 32.7 21.0 9.0 2.1 0.1 

Fifth child 7.8 0.1 6.9 18.7 15.1 7.6 2.0 0.1 

Sixth&seventh child- 7.3 0.0 3.0 15.1 16.3 9.6 2.8 0.2 

Eighth child & over-- 4.3 0.0 0.3 4.1 9.6 9.0 3.8 0.3 

White 103.7 0.4 68.2 224.9 181.2 102.3 48.8 13.4 0.8 

First child 29.4 0.3 50.0 83.9 24.8 7.2 2.6 0.6 0.0 

Second child 25.9 0.0 14.8 78.1 45.4 14.8 5.1 1.1 0.1 

Third child 19.6 0.0 2.9 40.9 48.4 23.0 8.5 1.8 0.1 

Fourth child 12.6 0.0 0.4 15.5 32.5 21.7 9.3 2.1 0.1” 

Fifth child 7.1 0.0 4.8 16.8 15.0 7.7 2.0 0.1 

Sixth&seventh child- 6.1 0.0 1.6 11.2 14.5 9.1 2.8 0.2 

Eighth child & over-- 2.9 0.0 0.1 2.0 6.2 6.6 3.0 0.3 

Nonwhite 144.8 4.0 139.9 278.1 211.2 128.9 68.9 21.0 1.5 

First child 33.8 3.8 82.9 64.7 18.5 6.2 2.5 0.5 0.1 

Second child 27.6 0.2 39.3 72.9 28.3 11.2 4.3 0.9 0.0 

Third child 21.8 0.0 13.5 61.1 33.8 14.5 5.7 1.2 0.1 . 

Fourth child 16.9 0.0 3.4 41.4 34.8 16.0 6.6 1.7 0.1 

Fifth child 13.1 0.7 22.9 32.8 16.3 7.2 1.9 0.1 

Sixth&seventh child- 16.6 0.1 13.5 43.8 29.8 14.0 3.7 0.3 

Eighth child & over-- 15.1 0.0 1.6 19.1 34.9 28.7 11.1 0.9 

lRates computed by relating total births, regardless of age of mother, to women
 aged 15-44 years.


2Rates computed by relating births to mothers aged 45 years and over to women aged


45-49 years.


16

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Fertility by Metropolitan Residence 

Birthsto residents ofmetropolitan
counties


accountedforabout64percentofthetotalbirths


occurring in the United Statesduring 1963.


Metropolitancountiesare thosedefinedby the


U.S. Bureau of the Census in 1960 as beingin


standardmetropolitan statistical
 areas(SMSA’s).


SMSA’S of 1’millionor more population
in


1963 accountedforaboutone-third
ofthebirths


occurringin the UnitedStatesduring1963,and


SMSA’s of 2 millionor more, for aboutone­


fourth.Table.5 shows thatbirthratesin the


largestSMSA’S varyaccordingtothegeographic


regionin which theseareasare situated.
 Within


allbutthe NorthCentralRegion,birthratesfor


SMSA’s witha population
of 1 millionor more


tend to fallbelow birthratesin the balanceof


theseregions.


Comparisonsofbirthrates
 among theSMSA’S


may reflect differences inactual reproductive
 be-


havior,but may alsobe influenced
 by thediffer­


encesinageand sexcomposition
ofthepopulation


intheseareas.


CHARACTERISTICS OF BIRTHS 

The followingsectionsdeal with certain


characteristics
 of birthsfor which allor most


registration areasprovideinformation.
 The char­


acteristics
for which data can be presented


are necessarilylimitedby the information
col­


lectedon the birthcertificate;
 therearecertain


importantcharacteristics, especially
thosere­


latingto thehealthof the newbornchildand its


mother, for which there is little
or no useful


information
atpresent.


Sex Ratio 

The sex ratioin 1963 turnedupward again


to 1,053males per 1,000 female births.This


isthesame as itwas 11yearsago.The nonwhite


ratio(1,030)
isthehighestithas beensince1942


(1;033).The whiteratioof 1,057is thehighest


since1953.


A comparisonofthesexratioforsingleand


forplurallivebirthsshows a higherproportion


of males in singlethan in pluraldeliveries.


This is due primarilyto a difference
 inthesex


Table 5. Birth rates for standard metro­


politan statistic 1 areas with popula­


tions of 1,000,000 or more by geograph­


ic region: United States, 1963


(Notes to tables given on page VII) 

Region and SMSA


Northeast


SMSA’S


Boston-Lowell-Lawrence,Mass-


Buffalo, N.Y-----------------


Newark, N.J------------------


New York, N.Y----------------


Paterson-Clifton-Passaic,N.J-


Philadelphia, Pa.-N.J--------


Pittsburghj Pa---------------


Balance of region--------


North Central


SMSA‘S -----------

Chicago, Ill-----------------


Cincinnati, Ohio-Ky


Cleveland, Ohio--------------
 Detroit, Mica----------------
 Kansas City, Mo.-Kens


Milwa-ukee,Wis---------------


Minneapoli-s-St.Paul, Mimn---


St. Louis, Mo.-Ill


Balance of region--------


South


SMSA’S-------------------


Atlanta, Ga------------------


Baltimore, Md----------------


Dallas, Tax------------------


Houston, Tax-----------------


Miami, Fla-------------------


Washington, D.C.-Md.-Va


Balance of region--------


West-------------------


SMSA’S-----------.-------

Denver, Cola-----------------
 Los Angeles-Long Beach Calif-


San Diego, Cali.f


San Franci-sco-Oakland,Cali_f-


Seattle, Wash----------------


Balance of region--------


Birth


rates


per 1,000


population


20.3


19.9 

21.3


20.7


19.7


19.9


18.8


20.9


18.7


20.7


21;8


22.3


22.5


23.0


20.8


21.3


22.2


22.8


24.9


22.2


21.5


22.7 

23.0


23.9


22.3


23.4


23.9


18.3 

24.7 

25.6 

22.0


21.3


22.9


21.3


23.2


20.3


21.1


22.4


17

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ratios for the white group between single and 

plural births (table 6). 

As in the past, the sex ratio for 1963 decreases with the age of the mother and livebirth order; however, this relationship does not 

usually hold true for a cross-classification of any 

single-birth order with any 5-year age-of-mother 

group, as shown in table 7. 

Plural Births 

Over the past 20 years there has been no 

noticeable trend in the rate of occurrence of 

plural births (table 8). Ninety-eight percent 

of the births still occur in single deliveries. 

Little change can be seen in the relationship 

between the age of the mother and the occurrence 

of plural births. The incidence of plural births 

increases with the age of the mother through 

age 39 and decreases slightly over age 40 (table 

9). 

The incidence of plural births differs among 

the races. In contrast to the proportion of 1 

plural birth out of 50 for all races combined, 

the incidence among white births is 1 out of 

54 and among nonwhite births 1 out of 38. A 

much higher twinning rate occurs among Negroes 

than among whites, while the oriental group 

has the lowest rate. 

Attendant at Birth 

In the past 20 years, the proportion of births 

occurring in hospitals has increased for both, 

color groups so that in 1963, 99.1 percent of the 

white births and 87.9 percent of the nonwhite 

births were in hospitals. For births outside hospitals, the percentage of both “physicians not 

in hospitals” and tlnonmedical deliveries” ‘emained constant for white and decreased for 

nonwhite births. Almost 10 percent of the nonwhite births are still delivered by midwives or ,. 

other persons who are not doctors. 

For the United States as a whole, 98.2 

percent of the births are medically attended: 

99.6 percent of white births and 90.3 percent of 

nonwhite births. Only in the South Atlantic and 

the East and West South Central Regions are the 

percentages of medically attended births noticeably lower for white and nonwhite births, as 

Table 6. Live births by sex and sex ratio at birth, by color and plurality: United 

States, 1963 

(Notes to tables given on page VII) 

Color and plurality 

Total 

Single 

Plural 

White 

Single 

Plural 

Nonwhite 

Single------------------------z------------

Plural 

Male Female 

Number 

2,101,632 1,996;388 

2,0:;,;;: 1,9::,;;: 

> 3 

1,709,174 1,617,170 

1,677>834 1,5;:,;:: 

31>340 > 

324,206 314,722 

315,766 306,512 

Ratio 

Males per ’1,000 

females 

1,053 

1,053 

1,026 

1,057 

1,057 

1,027 

1,030 

1,030 

8,440 8,210 1,028 

18 
Table 7. Sex ratio at birth. .- by live-birth order, color, and age of mother: United 

States, 1963 

(Notes to tables given on page VII) 

Color and age 

of mother 

Total 

All a.ges15-19 years----

20-24 years----

25-29 years----

30-34 years----

35-39 years----

40-44 years----

White 

All ages15-19 years----

20-24 years----

25-29 years----

30-34 years----

35-39 years----

40-44 years----

Nonwhite 

All ages15-19 years----

20-24 years----

25-29 years----

30-34 years----

35-39 years----

40-44 years----

Live-birth order 

I I I I I 

Sixth Total First Second Third Fourth Fifth and over 

Males per 1,000 females 

1.053 1,064 1,052 1,058 1,048 1.034 1,034 

1,064 1,070 1>057 1,028 1.032 966 1,143 

1,052 1>058 1,048 1,057 1;032 1,049 1,044 

1,057 1,070 1,057 1,062 1,063 1,042 1,032 

1,042 1,075 1,055 1,052 1,047 1,020 1,025 

1,046 1,057 1,054 1,070 1,040 1,027 1,044 

1,043 1,053 1,005 1,061 1,103 1,036 1,044 

1,057 1,071 1,052 1,061 1,051 1,033 1,045 

1,072 1,078 1,064 1,037 992 795 1,313 

1,055 1,062 1,049 1,059 1,042 1,050 1,070 

1,061 1,081 1,055 1,066 1,065 1,043 1,047 

1,045 1,078 1,054 1,057 1,045 1,020 1,032 

1,049 1,067 1,048 1.071 1,044 1,028 1,051 

1,050 1,091 991 1;050 1,051 1,032 1,065 

1,030 1,034 1,041 1,034 1,032 1,027 1,014 

1,041 1,045 1,039 1,025 1,051 1,066 1,097 

1,033 1,031 1,038 1,044 1,009 1,048 1,018 

1,028 1,008 1,060 1,028 1.050 1,030 1,009 

1,018 1,018 1,017 1,014 1;060 1,003 1,012 

1,024 987 1,039 1,031 1,014 1,001 1,029 

996 698 1,067 1,061 1,044 990 992 

can be seen in table 10. The highest infant and 

neonatal mortality rates are also recorded inthe 

South.i 

The only States in which fewer than 99percent of the white children were born in hos­ . . 

‘Details for each State are shown in National Center for 

Health’Statistics, VitaZS8atistics of the United State.e, 1963, 

Vol. II, Pt. A, Public Health Service, Washington, U.S. Government Printing Office, 1965. 

pitals are North Dakota, Virginia, West Virginia, 

Kentucky, Alabama, Arkansas, Texas, Colorado, 

New Mexico, and Arizona. However, only in 

14 States are more than 99 percent ofthe nonwhite births delivered in hospitals. These include all of the New England States and Ohio, 

Minnesota, Iowa, Nebraska, the District of Columbia, Idaho, Wyoming , and Hawaii. 

Over the past 13 years the increase inthe 

percentage of nonwhite births delivered inhos19 

c 
-----

-----

-----

-----

-----

-----

---

--

Table 8. Number of live births in plural


deliveries and ratio of plural live


births to total live births: United


States, 1944, 1950, and 1956-63


(Notes to tables given on page VII) 

Number of 

live births Ratio 

Year per 1,000
 in plural live births
 deliveries


1963------ 81,158 19.8 

1962------ 81,306 19.5 

1961------ 86,100 20.2 

1960------ 86,684 20.4 

1959------ 87,654 20.6 

1958------ 86,610 20.6 

1957------ 87,158 20.5 

1956------ 88,816 21.3 

1950------ 74,456 20.9 

1944------ 56,362 20.2 

Table 9. Ratio of plural live births to


total live births, by age of mother and


color: United States, 1963


(Notes h tables given on page VII) 

Age of mother Total White Nonwhite


I Ratio of plural live


births Der 1.000


‘115-19 years 12.0 11.4 14.0 

20-24 years 16.6 15.4 23.3 

25-29 years 21.6 20.2 30.5 

30-34 years 26.4 24.7 36.3 

35-39 years 29.4 27.8 38.7 

40-44 years 23.8 22.7 30.6 

pitals has been very dramatic in the regions 

where only a small proportion ofthe births were 

hospital deliveries in 1950 (fig. 6). 

‘E RCENT 

/“ 

_ESC /’ 

-.-.- New England 

mtam. mnm Middle Atlantic 

East North Central 

w=--= West North Central 

~—. South Atlantic 

20 – East South Central 

.-. West South Central 

m-w Mountain 

— Pacific 

t- i 

o	 ! 

19s0 1955 1960 196: 

Figure 6. Percent of nonwhite live births occur-


ring in hospitals, by geographic division,1950-


63.


Birth Weight and Period of Gestation 

In NataMyStatistics Anulysis 1962,thorough 

treatment was given to the data on birth weight 

and period of gestation showing trends since 

1950, when data on birth weight were first 

collected. There has been almost no change in 

the distribution of live births by weight between 

1962 and 1963. The median birth weight for all 

live births was3 ,290 grams (7 pounds ,40unces), 

the same as in 1962. There is a slightly larger 

percentage of immature births—those weighing 

20

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Table 10. Percent distribution of live births, by attendant according to geographic


division and color: United States, 1963


(Notes to tables given on page vII) 

Attendant


Geographic division and color Physician Physician Other


not in Midwife and not


hosp;~al hospital specified


United States


White


Nonwhite


Geographic divisions


) 

New England


White


Nonwhite


Middle Atlantic


White


Nonwhite


East North Central


White


Nonwhite


West North Central


White


Nonwhite


South Atlantic


White


Nonwhite------------------------------,---


East South Central


White


Nonwhite


West South Central


White


Nonwhite


Mountain


White


Nonwhite


Pacific


White


Nonwhite


Percent distribution


97.4 0.8 1.7 0.2 

99.1 0.5 0.3 

87.9 2.4 9.1 

99.7 0.3 0.0 0.0 

99.7 0.3 0.0 

99.5 0.4 0.6 0.1 

99.3 0.6 0.0 0.1 

99.4 0.5 0.0 0.1 

98.3 1.3 0.0 0.4 

99.2 0.7 0.0 0.1 

99.5 0.5 0.1 

97.1 2.2 M! 0.6 

99.3 0.5 0.1 0.1 

99.4 0.5 0.0 0.1 

97.2 1.2 1.3 0.3 

94.3 1.3 4.1 0,2 

99.3 0.4 0.1 

82.4 3.5 1%: 0.6 

88.6 1.7 9.4 0.3 

98.1 0.8 0.1 

65.4 4.1 2;:; 0.8 

95.3 0.8 3.5 0.3 

97.2 0.6 2.0 0.2 

88.5 1.6 9.2 0,6 

98.5 0.7 0.5 0.4 

98.6 0.7 0.4 0.2 

96.6 0.9 0.8 1.7 

99.2 0.6 0.1 0.2 

99.3 0.6 0.0 0.1 

98.2 0.8 0.4 0.6 

,. 21 .

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Table 11. Median birth weight and immature live births as percent of total live 

births, by plurality and color: United States, 1962 and 1963 

(Notes totabIesgivenonpageVII) “ 

Plurality and color 

Total 

White ---------------------------

Nonwhite ------------------------

Single 

White€

Nonwhite ------------------------€

Plural 

White ---------------------------

Nonwhite ------------------------

NOTE: An immature birth is one 

Table 12. Immature live births, 

Median weight Immature live births 

1963 1962 1963 1962


Weight in grams 

Percent of total 

live births 

3,290 3,290f 8.211 8.0 

I I I 

3,320 3,320 

3,140 3>140 M 1;:: 

3,300 3,300 7.2 7.1 

3,330 3,330 6.2 

3,150 3,150 1::: 11.8 

2,410 2,420 55.6 “55.1 ‘ 

2,450 2,450 53.5 53.0 

2,290 2,300 63.1 62.8 

weighing 2,500 grams or less. 

as percent of total live births, by color and urbanrural residence, for metropolitan and nonmetropolitan counties: United States, 1963 

(Notes totablesgivenonpageVII) 

Color and Total Metropolitan Nonmetropolitan 

urban-rural residence counties counties 

I Percent of’live births in each group 

HI 8“4! ‘7”7 

Urban 8.6 8.8 8.0 

Rural ------------------------------------- 7.4 7.2 7.5 

White --------------------------------- 7.0 

Total 

1+1 7“21 

Urban 7.2 

Rural ::; ::; 6.8’ 

Nonwhite ------------------------------ 13.6 14.4 12.1 

Urban 14.4 14.6 13.4 

Rural ------------------------------------- 11.8 12.7 11.5 

NOTE: An immature birth is one weighing 2,500 grams or less. 

22 
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------------------

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

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

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

2,500grams or 5 pounds, 8 ounces, or less—8.2 

percent, as compared with 8.0 percent in 1962. 

This reflects a greater increase in the proportion 

of immature infants among nonwhite than among 

white births, as can be seen in table 11. 

Single births have a higher average birth 

weight than do births in plural deliveries. Much 

of this difference is due to the large proportion 

of plural deliveries that are premature, in terms 

of length of gestation. Over half of the plural 

births are immature and therefore subject to a 

much higher risk of death than. children of mature weight. 

The incidence of immature births is greater 

among children born to mothers residing in 

metropolitan areas, as can be seen in table 12. 

The regional variation of birth weight continues to follow the same pattern as in 1962. The 

highest median birth weight for white births in 

1963 was in the West North Central States and 

the highest for nonwhite births was in the Mountain States. (Most of the nonwhite persons in 

these States are Indians.) The Mountain States 

show the smallest difference between median 

birth weights for white and nonwhite births 

(3,240 grams for white and 3,180 grams for nonwhite births). 

Since the weight of an infant at birth is 

determined primarily by the length of gestation, 

it is very important that, accurate data on this 

subject be collected. The best method so far 

developed to estimate length of pregnancy is to 

measure it from the date of the first day of the 

mother’s last menstrual period. At present, 

only 4 out of 54 birth regismation areas in the 

United States ask for this date on birth certificates: Baltimore, California, the District of 

Columbia, and New York City. Table 13 shows 

median birth weight for periods of gestation of 

28 weeks and over for white and Negro single 

live births in three of these areas (Baltimore 

is excluded because of tabulating problems). 

The length of the period of gestation is also 

used to define prematurity. A premature birth 

is one with a period of gestation of fewer than 

37 weeks. In most areas of the country (other 

than those mentioned in the preceding paragraph), 

the length of this period is estimated by the 

person giving information for the medical portion of the birth certificate (usually the doctor 

in attendance at birth). Because these reports 

are often inaccurate, they are not an ideal basis 

for statistics on prematurity. The proportion of 

infants reported to have been born after fewer 

than 37 weeks of gestation are as follows: 

Percent 

prem.atuve 

Total 6.8 

White 6.0 

Nonwhite 11.0 

Table 13. Median birth weight, by period of gestation, for white and Negro single live 

births: District of Columbia, California, and 

(Notes to tables given on page VII) 

District of Columbia 

Period of gestation 

White Negro 

New York City, 1963 

California New York City 

White Negro White Negro 

Weight in grams 

28-31 weeks 

32-35 weeks 

36 weeks 

37-’39 weeks 

40 weeks 

41-42 weeks 

43+ weeks---------------------,---­

1,970 

2,740 

2,960 

3,220 

3,360 

3.460 

3; 500 

2,390 1,720 

2,770 2,650 

2,870 2,910 

3,090 3,240


3,230 3,400


3,260 3,510


3,280 3,500


1,900 2,060 1,960 

2,680 2,740 2,690 

2>870 2,890 2,840 

3,130 3,170 3,080 

3,280 3,320 3,220 

3,350 3,400 3;270 

3,280 3,380 3,220 1 

23 
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----------

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

------

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

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

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

The proportion of 6.8 percent premature for 

the country as a whole is of the same order of 

magnitude as the proportion of 8.2 percent immature, but the latter figure is based on more 

precise data (birth weight), and probably gives 

a more accurate impression of the proportion 

of infants who face severe health risks in the 

first month of life. 

Season of Birth 

The number of births by month has exhibited 

a relatively stable seasonal pattern over a period 

of years. s For 1954-63, there was an average 

seasonal difference of about 13 percent in the 

number of births from the lowest to the highest 

month, from about 328,000 in April and May 

to 377,000 in September. (Births have been adjusted for the varying number of days in each 

month.) The average monthly numbers of births 

in this 10-year period are as follows: 

January 335,000 

February 343;000 

March 340,000 

April 328,000 

May 328,000 

June 341,000 

July 361,000 

August 371,000 

September 377,000 

October 358,000 

November 346,000 

December 345,000 

While the bimodal shape of the seasonal 

distribution prevails throughout the United States, 

there are marked variations in the amplitudeof 

the seasonal curve bycolorandgeographic region. 

These variations are shown below for 1963 in 

terms of standard deviations from an index 

representing the average monthly number of 

births per year for each group. 

Geographic region and 

color 

United States----

White 

Nonwhite 

Northeast 

White 

Nonwhite 

North Central 

White 

Nonwhite 

South ---------------

White 

Nonwhite 

West ---------------

White 

Standard 

deviation 

of monthly 

indexes 

4.0. 

2:: 

3.3 

2:: 

3.5 

7.2 

6.7 ; 

9.5 

3.4 

White-----------------Nonwhite--------------- 1 

For the total United States during 1963, the 

standard deviation of the seasonal pattern was 

4.0. This means that two-thirds of the monthly 

variation was within, 4 percent of the average 

birth rate for the year. For the period 1954-63, 

the standard deviation was 4.2; for1948-54,itwas 

4.6; and forthe 1933-40 period, 3.4. 

The distribution ofnonwhite births by month ‘ 

shows greater variation than that of white births; 

the standarddeviations in1963were,respectively, 

6.6 and 3.8. This difference prevailed for allof 

the geographic divisions of the United States. In 

the South the seasonal patternexhibitedthegreatest amplitude; in the Northeast, the least. 

Removal of the large month-to-month fluetuations in the number of births facilitates observation of the underlying trend in the birth 

rate on a monthly basis. This has beetiaccomplished by seasonally adjusting the time series, 

24 

,, 
,—,Trend.cycle 

Seasonally 

“’’’’’’”’”’’’’adjusted rates 

\. 1 .. —tidlbserved rates 

20 L -1. 1 -1- L L 

— — — — 

o	 1111111111111111111111111111 1111.1111 111111111111 111111111111 11111111111 Lllllll ii 

J FMAMJJASONDJFMAMJJ ASONDJFMAMJJASONOJ FMAMJJASONDJFM.AMJ JAsoNDJFMAMJJAsoND JFMAMJJAsoND 

1957 1958 1959 1960 1961 1962 1963 

‘igure7. Birth rates by month: obS.8rVed rates, seasonally adjusted rates, and trend-cycle, 1957-63.


(Rates are on an annual basis per 1,000 population for specified month. Beginning in 1959 trend lines


for 1957-59 are based on live births adjusted for
 are based on registered live births; trend lines


underregistrati on;


using an adaptation of the standard ratio-tomoving-average method.6 Figure7 showsmonthly 

birth rates for 1957-63 from which seasonal 

fluctuations have been removed. This represents 

the underlying trend and random movements in 

the time series . Eliminationof therandommovements from seasonally adjusted data delineates 

even more sharply the underlying trend, in a 

series called the “trend-cycle.” 

Figure 7indicates that thetrend of the birth 

rate reached a postwar peak in July 1957, from 

which it declined, with an interruptionin late 

1960, tbrough 1963. 

Illegitimacy


The number of illegitimate births in the 

United States is estimated from numbers reported in 34 States andthe District of Columbia. 

In”1963, the number of illegitimate births continued to increase, with 183,440 such births 

occurring in the reporting areas andanestimated 

75,960 taking place in the other areas, bringing 

the estimated total for the United States to 

259,400, or 63.3 illegitimate births per 1,000 

live births. For white births the illegitimacy 

ratio was 30.7 and for nonwhite.births the ratio 

25


I 
was 235.9 illegitimate births per 1,000 live 

births. 

In making estimates of the number of illegitimate births occurring in the country as a whole, 

the States are grouped into nine geographic 

divisions. The ratio of illegitimate to total live 

births for the 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. 

The trend in the illegitimacy ratio since 

1940 can be seen in figure 8. For the early years 

of this period the patterns for white and nonwhite 

I,000 

800 

600 

400 

m


r Nonwhite
 1-


=


d 200 

w 

> 

z 

-1 

~ 

: 100 

0


0 80
 0


_.


m 60 u 

n 

In 

0 

i= 40 a

E 

20 

10 

1940 1945 [950 1955 1960 196 

Figure 8. Illegitimacy ratios, by color, 1940-63. 

(Logarithmic scale)


births are quite similar. Starting in 1958, however, the illegitimacy ratio for white births, 

which had been fairly steady for several years, 

began to increase more rapidly and has continued to do so through 1963. The ratio for 

nonwhite births, on the other hand, has continued a rather slow upward trend. Between 

1962 and 1963 the illegitimacy ratio for white 

births increased by 11.6 percent; the ratio for 

nonwhite births” increased by only 2.6 percent. 

The differentials by age of mother are essentially the same in 1963 as in former years. 

Women under 15 years of age have the highest 

illegitimacy ratios, while there is a decrease 

in the ratios by age through the thirties and a 

slight upturn among women over 40 (table 14). 

In order to measure the trend in illegitimacy 

more adequately, a rate of illegitimate births 

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

(the population at risk) is used. This rate has 

varied only slightly over the past 4 years 

1963 ---------------------------- 22.5 ~, 

1962 ---------------------------- 21.5 

1961 ---------------------------- 22.6 

1960 ---------------------------- 21.8 

A more adequate description of trends could 

be made with the use of illegitimacy rates by 

age of mother and color. Estimates of such ,rates 

are being prepared and will be included in a report on illegitimacy to be published in the near 

future. 

The general pattern of an increase in the 

occurrence of illegitimate births is shown by 

the illegitimacy ratios for each of the States 

that report the legitimacy status of child on the 

birth certificate. j Over the 4-year period, 1960-

63, the illegitimacy ratio for white births has 

increased consistently in 19 States and the 

District of Columbia, and has shown a general, 

but not continuous, increase in the remaining 

15 States of the reporting area. For nonwhite 

births there were continuous increases in only 

13 States, in North Dakota and Rhode Island there 

were continuous declines in the ratios, and in 

the other States the trend, although predominantly 

upward, was not continuous. 

jThe data are presented in table 1-$,29of National ‘Center 

for Health Statistics, Vital SWistics o~ the United States, 

1963, Vol. I, Public Health Service, Washington, U.S. Government Printing Office, 1964. 

26

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

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

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

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

Table 14. Estimated number and ratio of illegitimate live births, by age of mother and 

color: United states, 1963 

(Notes to tables given on page VII) 

Age of mother Total White Nonwhite 

?umber of illegitimate live Ratio per 1,000 

births total live births 

To~al.------------------. 259.400 102,200 150,700 63.3 30.7 235.9 

Under 15 veals 5,400 

15-19 years----------, 101,800 

15-17 years 51,100 

18 and 19 years 50,700 

20-24 years 82,600 

25-29 years 35,400 

30-34 years 19,800 

35-39 years 10,900 

40+ years 3,500 

BIRTHS IN PUERTO RICOAND ! 

THE VIRGIN ISLANDS 

Levels and Trends 

In 1963, as in the past, birthrates in Puerto 

Rico and the Virgin Islands were higher than 

that of the United States (table 15). Puerto Rico’s 

birth rate of 30.6 per 1,000 population was 41 

percenthigher than the rate of21.7for the United 

States, and the Virgin Islands’ rate of38.1 was 

76 percent above that for the United States. Only 

one State, Alaska, had a higher birth rate than 

Puerto Rico (31.0, compared with 30.6), andno 

State had ahigher rate than the Virgin Islands. 

Assuming that the 1963 birth and death 

rates were to prevail indefinitely and that the 

respective areas were closed to in- and outmigration, the population of the United States 

would double in 46 years, Puerto Rico in 33 

years, and the Virgin Islands in 26years. Sucli 

rates, although hypothetical, emphasize thedifferent potentials for population growth offered 

by current birth and death rates in these areas. 

Birth rates in the United States are below 

those in Puerto Rico, in part, because ofdifferences in the age-sex compositions of the respective populations. Adjusting for these differ1,200 4,000 711.1 464.4 830.9 

39,800 59,300 173.6 89.8 454.4 

17,900 31,800 283.0 146.6 579.8 

21,900 27,500 124.9 68.2 363.5 

35,900 44,400 56.8 29.8 213.8 

12>800 21,800 34.6 15.2 152.7 

6,900 12,600 32.4 13.9 Uko.3 

4,100 6,600 33.8 15.7 135.4 

1,500 2,000 37.3 19.7 137.5 

ences, using the 1963 age distribution ofwomen 

in the United States as a standard, yields an 

age-sex-standardized birth rate for Puerto Rico 

that is only 22 percent above the birthrate of the 

United States.k In other words, about half of the 

41-percent difference between the unadjusted 

birth rates of Puerto Rico and the United States 

is due to differences in age-sex composition. 

The remainder of the difference isdue to higher 

age-specific birthrates in Puerto Rico. 

Trends in the birth rate, which are shown 

in table 15, have not been the same for Puerto 

Rico and the Virgin Islands as for the United 

States. In Puerto Rico, the birth rate reached 

a postwar peak of 42.2 in 1947 and has declined 

fairly steadily since then. In the Virgin Islands, 

however, the 1962 birth rate of 39.4 was the 

highest observed in the postwar period. The lowest postwar rate, 30.7, was recorded in1948. In 

general, there has been an upward trend inthe 

birth rate in the Virgin Islands, butit has been 

‘Based on female age-specific birth-rate estimates prepared by the Puerto RICO Deparhnent of Health, Division of 

Demographic Ftegistry and Vital Statistics, and shown in table 

llof Annual Vital Statistics Repo?~, 1963. The 1963 age-sex 

adjusted rate for Puerto Rico is 26.4 births per 1,000 population. 

27 
----

----

---

---

---

---

---

---

------ ---

----- ---

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

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

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

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

Table 15. Live births and birth rates: 

Puerto Rico and Virgin Islands, 1940-63 

(Notes to tables given on page VII) 

, 

Puerto Rico Virgin Islands 

Year 

Number Rate Number Rate 

l$Mj31----

19621-.-- 77,440 

76,596 

30.6 

31.1 

1,513 

1,375 

38.1 

39.4 

19611---- 75,418 31.3 1,193 33.8 

19601 76,314 32.5 1,180 36.8 

19591----

19581----

19571----

75,104 

76,298 

76,058 

32.3 

33.2 

33.7 

1,107 

1,129 

1,038 

35.7 

37.6 

35.3 

19561---- 78,284 34.8 977 34.4 

1955----- 77,830 34.6 913 33.1 

‘ 19541---- 77,832 35.2 879 32.3 

;;@---- 77,754 35.3 871 32.4 

80,438 36.1 862 30.9 

19511---- 84,076 37.6 953 34.4 

1950----- 86,038 38.9 894 33.5 

1949----- 85,625 39.0 886 33.2 

1948----- 87,809 40.2 826 30.7 

1947----- 91,305 42.2 876 32.2 

19462---- 88,421 41.6 917 34.0 

1945:---- 86,680 41.9 984 37.4 

1944d---- 82,534 40.6 1,059 40.4 

19432---- 77,304 38.7 931 37.4 

19422 ---- 889 35.8 

19412---- 829 32.6 

1940----- 756 30.4 

lFor Puerto Rico, based on a 50-percent sample of births; 

2Rates based on civilian population in 

each area. 

irregular. Part of this irregularity may be due 

to random variations associated with small numbersofbirths (800 to l,500inthepostwar period). 

Health Characteristics of the 

Newborn infant 

Health indexes of thenewborn infantinPuerto 

Rico and the Virgin Islands wereat measurably 

lower levels in 1963 than in the United States. 

The percentage of births delivered in hospitals 

was 84.9 in Puerto Rico and 87.7 in the Virgin 

Islands compared with 97.4 in the United States. 

Since hospitals are concentrated in urban areas, 

the percent of in-hospital births is associated 

with the degree to whichapopulationis urbanized, 

which is also highest in the United States. The 

percentages of in-hospital births to residentsof 

metropolitan areas in Puerto Rico and to urban 

residents in the Virgin Islands areclosertothose 

of comparable populations in the United States as 

shown below. 

I I -“1 

Residence	 United Puerto Virgin

States Rico Islands 

Percent of births” 

in hospitals 

Total- 97.41 84.9 I 87.7 

SMSA 98.9 91.5 

Urban 98.4 ‘98.9 

lIncludes only the cit of Charlotte 

Amkn~~e (St. Thomas Island r , Virgin ls-(, . 

Puerto Rico and the Virgin Islands show 

higher percentages of immature births than does 

the United States. The percent Of live births ‘ 

weighing 2,500 grams or less was 8.2 in the 

United States, 8.9 in the Virgin Islands, and9.8 

in Puerto Rico in 1963. 

There is some evidence that immaturity 

is more frequent in the lower socioeconomic 

classes of Puerto Rico. This is shown by the 

percentage of immature births in 1962,according 

to the education of the father. (This tabulation 

is not available for 1963.) 

I Percent 

immature Highest gra”de completed (2g~O~e~;ms 

No schooling 

1-4 years 

5-8 years 

9-11 years 

12 years 

13+ years 

28 
REFERENCES


lFreedman, R., Whelpton, P. K., and Campbell, A. A.: 5

National Office of Vital Statistics: Seaeonal variations 

Famity Planning, Sterility, and Population Growth. New York. of bi rtbs in the United States, 1948-54, by D. E. Waggoner 

McGraw-Hill Book Co., 1959. p. 382. and J. Schachter. Vital Statistics–SpeciaJ Reporte, Vol. 47, 

2Freedman, R., Goldberg, D., and Bumpaes, L.: Current No. 4. Public Health Service. Washington, D. C., Apr. 1959. 

fertility expectations of married couples in the United States, 6

Rosenberg, H.: Seasonal adjustment of vital statistics 

1963. Popuz. Index. 31:3-20, Jan. 1965. by electronic computer. Pd. HeaW Rep. 80:201-210, Mar. 

31bid, p. 9. 1965. 

4 

Winter, I. C.: The incidence of thromboembolism in Enovid users. Metabolism: Clinical and Experimental. 14:422-

428, Mar. 1965. 

000 

29 

U.S. GOVERNMENT PRINTING OFFICE , 1966 0—207-044 
OUTLINE OF REPORT SERIES FOR VITAL AND HEALTH STATISTICS 

Public Health Service Publication No. 1000 

Sevies 1. PTo~arns ami collection procedures. —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. 

Reports number 1-4 

Sevies 2.	 Rata evaluation and methods reseaych. —Studies of new statistical methodology including: experimental 

tests of new survey methcds, studies of vital statistics collection methods, new analytical techniques, 

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

Reports number 1-13 

Sen”es 3.	 Analytical studies. —Reports presenting analytical or interpretive studies based on vitsil and health statistics, carrying the analysis further than the expository types of reporta in the other series. 

Reports number 1-4 

Sen-es 4. Documents and committee reports .—Final reports of major committees concerned with vital and health 

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

death certificates. 

Reports number 1 and 2 

Seyies 10.	 Data From the Health InteYuiew SuYVey.— Statistics on illness, accidental injuries, disability, use of 

hospital, medical, dental, and other services, and other health-related topics, based on data collected in 

a continuing national household interview survey. 

Reports number 1-27 

Series Il.	 Data FYom the Health Examination Survey.— Statistics based on the direct examination, testing, and 

measurement of national samples of the population, including the medically defined prevalence of specific diseases, and distributions of the population with respect to various physical and physiological 

measurements. 

Reports number 1-12 

SeTies 1.3.	 Data FYom the Health RecoYds SWvey. —Statistics from records of hospital discharges and statistics 

relating to the health characteristics of persons in institutions,. and on hospiti, medical, nursing, and 

personal care received, based on national samples of establishments prcwiding these services and 

samples of the residents or patients. 

Reports number 1-4 

Series .20.	 Data on moytality. —Various statistics on mortality other than as included in annual or monthly reportaspecial analyses by cause of death, age, and other demographic variables, sIso geographic and time 

series analyses. 

Reports number 1 

Seyies 21.	 Data on natality, marriage, and divoyce. —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 fertility. 

Reports number 1-8 

Sew-es 22,	 Data Fyom the National NataZity and MoYtality Swveys. —Statistics on characteristics of births and 

deaths not available from the vital records, based on 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. 

Reports number 1