FROM VITAL & HEALTH STATISTICS OF THE NATIONAL CENTER FOR HEALTH STATISTICS 

U.S. DEPARTMENT OF HEALTH, . Public Health Service


EDUCATION, AND WELFARE Office of Health Research, Statistics, and Technology Number 59 � March 28,1980


Trends in Breast Feeding’ 

INTRODUCTION 

Findings presented in this report from Cycle 

II of the National Survey of Family Growth 

(NSFG) confirm a significant reversal of the 

trends in breast feeding among American mothers 

described in detail in an earlier report based on 

Cycle I of the survey.z These data show that the 

downward trend that had been in progress since 

the 1950’s was reversed in the early 1970’s. 

In 1973 the proportion of babies breast fed 

was 25 percent; in 1975 it was 35 percent. 

Breast feeding was more common among white 

women than black women: 33 percent of the 

babies born to white women in 1973-75 were 

breast fed, compared with only 15 percent of 

the babies born to black women. Also, breast 

feeding was more common among women with 

more years of education: 48 percent of babies 

born in 1973-75 to mothers with more than 12 

years of education were breast fed, compared 

with 24 percent of the babies born to women 

with 12 years of education or less. 

These findings are based on a special analysis 

of data from Cycle II, conducted in 1976 by the 

National Center for Health Statistics, and are 

reported in the Advance Data series because they 

substantiate the tentative conclusion of the 

earlier report that breast feeding was increasing. 

The data were collected by personaI interviews 

lThis report was prepared by Gerry E. Hendershot, 

Ph. D., Division of Vital Statistics. 

2National Center for Health Statistics: Trends in 

breast feeding among American mothers, by C. Hirschman and G. Hendershot. Vital and Health Statistics. 

Series 23-No. 3. DHEW Pub. No. (PHS) 79-1979. Public 

Health Service. Washington. U.S. Government Printing 

Office, Nov. 1979. 

with women in a representative sample of households in the conterminous United States. Women 

were eli~ble for the interview if they were 15-44 

years of age and either married, divorced, 

widowed, or never married but with offspring 

living in the household. The statistics in this 

report are for babies born to women in the 

sampled population during 1973-75. 

The statistics in this report may differ from 

those which would be obtained from a complete 

enumeration of the population because of 

sampling variability. The sample desiegn, sampling 

variability, and definitions of terms are discussed 

in the Technical Notes. 

To obtain information about breast feeding, 

mothers were asked about each baby who had 

lived with them for 2 months or more: “Did you 

breast feed him (or her) at aII?” If she had breast 

fed at all, she was also asked: “How many weeks 

old was he (or she) when you quit breast feeding 

him (or her) altogether?” Table 1 shows the 

estimated number of babies born in 1973-75 

and the percent breast fed at all (wholly or 

partially), by year of the birth, birth order, 

baby’s sex, mother’s race, and mother’s education. 

FINDINGS 

About 25 percent of the babies born in 1973 

were breast fed, but that figure increased to 

nearly 35 percent in 1975 for an average of 30 

percent over the period 1973-75. Because these 

estimates are based on small samples, differences 

of a few percentage points may reflect chance 

sampling variation, not true differences in the 

population. However, the probability is less 

than 0.10 that the difference between the 1973 

and 1975 estimates resulted from chance. It is 
Table 1. Number of babies who lived with their mother for 2 months or more and percent breast fed, by year of baby’s birth, baby’s 

birth order, baby’s sex, mothefs race, and mother’s education: United States, 1973-75 

~ Year of baby’s birth 

Characteristic 

973-7!5 1975 1974 1973 973-75 19?5 1974 1973 

Number in thousands Percent breast fed 

Totall. .. ..... .. .. .. .... .. ... .. .. .. ...... . ... .. ..... ..... . ... .... . 9,379 2,939 3,269 3,171 29.8 34.5 30.6 24.7 

Birth order 

3,903 1,176 1,318 1,410 33.2 37.0 37.2 26.3 

3,068 960 1,175 934 29.4 35.9 27.9 *24.5 

Sex of baby 

4,689 1,424 1,704 1,561 28.1 32.8 29.4 22.5 

4,690 1,515 1,564 1,610 31.5 36.1 31.9 26.8 

Mother’s race 

7,743 2,401 2,761 2,581 32.7 37.8 33.6 27.1 

1,425 491 458 476 *1 4.9 *1 6.8 *1 5.6 *I 2.3 

12 years or less............................. ....................... ....... 6,978 2,152 2,41 C 2,416 23.5 28.2 23.6 19.2 

More than 12 years .................. .................. .......... ....... 2,383 775 852 755 48.1 51.9 49.9 42.2 1 I 

I Inc]ude$ third and higher order births, races other than white or black, and unknown education. � 

likely, therefore, that the difference reflects a report cited before it was estimated that about 

true increase in breast feeding. That conclusion 7 percent of babies born in 1971-73 were breast 

is supported by the consistency of the increase fed for 3 months or more. The Cycle II estimate 

in subgroups of the population: in every cate- of that figure in 1973-75 is about 4 percent. 

gory of birth order, sex, race, and education While the difference between these estimates 

shown in table 1 the percent breast fed is greater is not large enough to conclude with statistical 

for 1975 than for 1973, although due to sampling confidence that there was a decrease in longer 

variability none of these individual differences term breast feeding, it may be concluded that 

is statistically significant in itself. there was no significant increase. Thus, although 

The increase in breast feeding between 1973 the proportion of babies receiving some breast 

and 1975 confirms the tentative observation in feeding increased in the early 19 70’s, the proan earlier report, 2 based on Cycle I of the portion breast fed for long periods did not 

National Survey of Family Growth, that the increase. For- a large majority of breast-fed 

downward trend in breast feeding which had babies, breast feeding ended before age 3 months, 

been in progress since the 1950’s was reversed in much younger than the 5-6 months recommended 

the early 1970 ‘s. Although breast feeding still by pediatric authorities.3 

was not as common in 1975 as it was in the The large differences between the breast1940’s (when more than one-half of babies were feeding practices of black and white women 

breast fed), it was more common in 1975 than which were found in the Cycle I report continued 

in the late 1960’s (when less than one-fourth of in 1973-75: in each of these years, babies born 

babies were breast fed). 

Breast feeding became more common in the 

early 1970’s, but it continued to be of relatively 3 ~omon, fj. J., et ~.: Recommendations for feeding 

e short duration for most babies. In the Cycle I normal infants. F’eclsiztrics 63(l) :52-59, Jan. 1979. 
9 dmcedaa3 

PERCENT OF BABIES WHO WERE BREAST 

FED, BY YEAR OF BABY’S BIRTH 

AND MOTHER’S EDUCATION: UNITED 

STATES, 1973-75 

Education: 

n 12 years or less 

- More than 12 years 

60 r 

50 

40 

30 

20 

10 

0 

51.9 

49.9 

1973 1974 1975 

YEAR OF BABY’S BIRTH 

to white mothers in the sample were more than 

twice as likely to be breast fed as babies born to 

black mothers. In fact, the racial difference in 

breast feeding appeared to be larger in 1975 

than in 1973, aIthough the increase was not 

statistically significant. The difference in breast 

feeding by educational attainment noted in the 

earlier report also continued in 1973-75: babies 

born to women in the sample with more than 

12 years of education were more than twice 

as likely to be breast fed as other babies. By 

1974 about one-half of babies born to women 

with some college education were breast fed (see 

the figure). Thus breast feeding continued to be 

more prevalent in relatively advantaged segments 

of the population. 

Differences in the percent breast fed by birth 

order and sex are not large (table 1), and in no 

case are they statistically significant. However, 

the slightly higher percent breast fed among 

first-born babies than second-born babies also 

was found in the CycIe I report. This consistency 

between survey findings is evidence that the 

difference by birth order for 1973-75 shown in 

tabIe 1 is probably real. 
4 dwmecaa 

TECHNICAL NOTES 

SAMPLE DESIGN AND RELIABILITY 

OF ESTIMATES 

In Cycle Hofthe National Survey of FamiIy 

Growth interviews were conducted with women 

living in households selected by a multistage area 

probability design. Sampling and interviewing 

were done by Westat, Inc., from January tk-ough 

September 1976. About 93 percent of sample 

households (33,000) were successfully screened 

for eligible women, and about 88 percent of 

identified eligible women (8,6 11) were interviewed, an overall response rate of about 82 percent. The statistics in this report are estimates 

for the national population and were computed 

by multiplying each sample case by the number 

of women she represented in the population. 

The multipliers, or “weights,” ranged from 647 

to 43,024 and averaged 3,822. 

Because the estimates are based on a sample 

rather than the whole population, they are subject to sampling variability, chance differences 

between the sample estimate and the actual 

population value. Sampling variability is measured by a statistic called the standard error. 

Provisional approximate standard errors for 

numbers and percents of babies are shown in 

tables I and II. Because of different sampling 

rates for the samples of black women and 

white women, standard errors for statistics 

based on these two racial groups are somewhat 

different. The estimates in tables I and II should 

be multiplied by 1.05 for black women and by 

0.97 for white women. Estimates for numbers 

and percents not shown in the tables may be 

approximated by interpolation. In this report 

statistics whose standard error was 25 percent 

Table 1. Provisional approximate standard errors for estimated 

numbers of babies: National Survey of Family Growth, 1976 

I 

Standard Size of estimate I error

5oo.ooo.................................................................. 113,000 

l.ooo.ooo ............................................................... 159,000 

2.500.000............................................................... 251,000 

5.000.000............................................................... 351,000 

lo.ooorooo............................................................. 485,000 

Table 11. Provisional approximate standard errors expressed in 

percentage points for estimated percents of babies: National 

Survey of Family Growth, 1976 

1 

Base of Est i ted I 

parcent 10 20 30 40 50 

700,000................................. 5.8 7.6 8.7 9.4 9.6 

1,000,000.............................. 4.8 6.4 7.3 7.8 8.0 

3,000,000.............................. 2.7 3.7 4.3 4.5 4.6 

7,000,000.............................. 1.9 2.4 2.7 2.9 3.1 

10,000,000............................ 1.5 2.1 2.3 T 2.5 2.5

or more of the estimate itself were considered 

unreliable, and they are marked with an asterisk. 

Unreliable estimates should be used only with 

great caution. 

The differences between statistics in this 

report are also subject to sampling variability. 

All differences mentioned in the text were 

is 

tested 

asserted 

for statistical 

without qualification 

significance. 

in 

If a 

the 

difference 

text, it �

is significant at the 0.05 level—there is less than 

1 chance in 20 that the difference resulted from 

a chance sampling fluctuation. Where a significance level of 0.10 was used—less than 1 chance 

in 10 that a difference occurred by chance-that 

is specified in the text. Differences described as 

“not statistically significant” could have occurred 

by chance in more than 10 percent of repeated 

samples. Absence of comment about a difference 

does not necessarily mean that it was tested and 

found to be not statistically significant. 

Estimates of numbers of babies shown in 

this report may differ from numbers of births in 

the same period obtained from the vital registration system for several reasons: (1) These estimates are based on a sample, while the birth 

registration system is a mechanism for registering 

all births occurring within the United States; (2) 

the sample did not include Alaska and Hawaii, 

military bases, group quarters, or institutions; 

(3) babies born in the period who did not live 

with their mother for at least 2 months after 

birth are not included in this report. For numbers 

of births, Volume I of Vital Statistics of the 

United States for 1973, 1974, and 1975 should o 

be consulted. 
ackincedata 5 

* 

DEFINITIONS OF TERMS 

Breast feeding. –Babies who lived with their 

mothers for at least 2 months after birth and 

whose mothers reported they had been breast 

fed “at all” are classified as having been breast 

fed. Included in this definition are both “longterrn” breast feeding (3 months or more) and 

“short-term” breast feeding (less than 3 months) 

and both supplemented and unsupplemented 

breast feeding. 

Race. –Classification of the race of the respondent as white, bIack, or other is based on 

observation by the interviewer. 

Education. –Women are classified according 

to the highest year of regular schooling they 

reported having completed. 

Birth order. –Babies are classified according 

to their numerical order among the Iive births 

reported by their mother—first, second, and so 

on. Babies within muItipIe live births are assumed 

to have been born in the order reported by their 

mother. 
---

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

6 aiwlncedata 

o 

SYMBOLS 

Data not available—-----------------—----------

Category not applicable . . . 

Quantity zero -------------------------------------- -

Quantity more than Obut less than 0.05---- 0.0 

Figure does not meet standards of 

reliability or precision (more than 

30 percent relative standard error)-----—— * 

I I 
Recent Issues of Advance Data From Vital and Health Statistics 

No. 58.	 Remarriages of Women 15-44 Years of Age Mothers 15-44 Years of Age: United States, 

Whose First Marriage Ended in Divorce: 1976 (Issued: January 24, 1980) 

United States, 1976 (Issued: February 14, 

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A complete list of Advance Data From Vital and Health StatsWcs is available from the Scientific and Technical 

Information Branch.