Eva J. Salber, M.D., and Manning Feinleib, M.D.
Department of Epidemiology, Harvard University School of Public Health, Boston, Massachusetts
(Submitted May 5; revision accepted for publication October 13, 1965.)
This study was aided by a Program Project Grant (CA 06373) from the National Cancer Institute,
U.S. Public Health Service, and by the General Research Support Grant of the U.S. Public Health
Service to the Harvard School of Public Health (5 501-FR-5446-04). ADDRESS: (E.J.S.) 1 Shattuck Street, Boston 15, Massachusetts.
PEDIATRICS, VOL. 37, No. 2, FEBRUARY 1966
BREAST-FEEDING
IN BOSTON
T
HERE has been great variation in thebreast-feeding patterns of American
women during the past generation. On the
basis of a national survey, Katherine Bain
reported in 1948 that 65% of mothers were nursing to some extent on discharge from hospital.’ Ten years later, Meyer found in
another national survey that only 37% of mothers were lactating at time of hospital
d2
These studies revealed marked regional differences in incidence of breast-feeding.
In Bain’s study, 33% of Massachusetts women were lactating at the end of their
hospital confinement, while ten years later only 18% were lactating at that time. Al-though breast-feeding rates were higher in
virtually all other states, the marked
de-crease during the decade was present in each state.
Other studies ilave shown that there is
wide variation in breast-feeding patterns according to social class, and that this
pat-tern has changed during the past thirty-five years. Garland and Rich, in 1930, found a greater frequency of breast-feeding among
tile lower social class women at the Massa-chusetts General Hospital,3 and Davis and Havighurst came to the same conclusion in
Chicago in 1946. However, Sears and his colleagues found in 1955 that in Greater
Boston more middle-class mothers (43%) lac-tated than did lower-class mothers (37%).5
Subsequent studies in New York in 19576
and again in Boston in 1958 have
con-firmed the finding of more breast-feeding among the upper socioeconomic groups.
The present study is concerned with the
continuation of these trends in
breast-feed-ing incidence among Boston mothers and also with the duration of breast-feeding. The differences in breast-feeding behavior exhibited by different socioeconomic groups is further examined, and the effects of age,
parity, and nativity are explored.
METHODOLOGY
The study group consisted of all white
mothers resident in Metropolitan Boston who delivered single, live, legitimate babies
in hospitals in Boston, Brookline, or New-ton, Massachusetts, in August or
Septem-her, 1963. There were 2,735 such mothers.
Information abstracted from the birth
certificates included father’s name, address, and occupation, mother’s age at the time of
birth of the baby, and the baby’s date of birth, sex, birth rank, birth weight, and hos-pital of birth. Since special feeding proce-dures are used for premature infants, 173
abstracts were excluded because the birth weight was less than 5 lb 8 oz or because birth weight was not recorded. Ninety-six
cases were subsequently excluded because
of unknown address, 12 because babies had died in the interim period, and 1 because of death of the mother.
Letters and questionnaries were sent to
the remaining 2,453 mothers during Janu-ary, 1964, when the babies were between 4 and 5 months old. Mothers who did not reply to the first letter were sent a reminder with-in 2 to 3 weeks, and those who failed to
reply to a second letter were contacted by
telephone if possible. Of the 2,453 mothers
in the “target” population, 2,233 (91%) re-sponded.
Duration of
Breast-Feeding
Did not breast-feed
1- 9 days
30- 59 days
60- 89 days
90-119 days
10-149 days
150-179 days
180-09 days
10-39 days
40-269 days
270-299 days
300-39 days
Total
Number
1,736 100
79
58
53
64
41
33 12 20 9
Percentage of Total
77.7 4.5
3.5
2.4
2.9
1.3 1.8
1.5
0.5 0.9 0.4
100.0 99.9
300
TABLE I
INCIDENCE AND DURATION OF BREAST-FEEDING
AMONG ,9233 BOSTON MOTHERS
Percentage of
Breast-Feeders
2O.1
1.5.9
11.7
10.7
12 .9
5.6
8J2
6.6
2.4
4.0
1.8
asked whether they had ever breast-fed their babies, date of weaning babies, and time when their first menstrual period re-turned after childbirth. All mothers who
in-dicated that they had breast-fed their in-fants for 3 months or longer were contacted
again by telephone and information about
supplemental bottle feeding and introduc-tion of solid food was obtained. All the mothers who continued to breast-feed were followed at monthly intervals until either the child was weaned, or contact was lost
(6 mothers). Twelve mothers were still nursing when the study was terminated on June 30, 1964.
The statistical analysis of the data em-ployed chi-square tests with partitioning to test for differences in the incidence of
breast-feeding (proportions) and analyses of variance and Scheffe’s method of
multi-pie comparisons to test for differences in mean duration of nursing of those mothers who nursed. Since numerous tests of
significance were planned, the level of significance was set at 0.01 at the beginning of the analysis. For those mothers who were still nursing at last contact, duration of nursing was arbitrarily taken as the age of the child at that time.
RESULTS
Incidence and Duration of Breast-Feeding The distribution of the study population
by duration of breast-feeding is shown in
Table I. Four hundred and ninety-seven
mothers (22.3%) attempted breast-feeding,
and 77.7% did not. The majority of
moth-ers who attempted breast-feeding (58.4%) weaned the infant prior to 4 months of age, while 23.0% (5.2% of the total group)
con-tinued to nurse for more than 6 months.
Variables Which Did Not Affect
Breast-Feeding
Within the range of birth weights
in-eluded in this study (5 lb 8 oz or more) no association between weight at birth and type of feeding was found. Similarly, sex of baby apparently did not affect the type of
feeding chosen.
Variables Affecting Breast-Feeding
Four variables were found to be related
to the incidence and duration of
breast-feeding. These are age of mother, her birth-place, the number of previous children she
has borne, and her social class. Social class was calculated from the occupation of the
father using a modification of Warner’s classffication.8 The relation of these vari-ables to breast-feeding incidence and dura-tion is shown in Table II.
Social Class
The greatest variation in breast-feeding
incidence occurred when the mothers were separated by social class. As in the pre-viously mentioned studies,5,6,7 mothers in the higher socioeconomic groups (Warner’s classes 1 and 2) nursed significantly more
often than did women from lower
socioeco-nomic groups. However, the greatest inci-dence of breast-feeding was found among those mothers who were married to stu-dents. Sixty-nine per cent of these mothers attempted breast-feeding as compared with 39.8% of mothers in social classes 1 and 2
T0tal
Number
Number
Breast-.
Feeding
Percentage
Breast-.
Feeding
P For
Dijerence in
.
Proportlon
Mean
Duration (days)
P For
Dijerence in Means
By age of mother
Less than 25
5-9 S0andover
790
675
768
193
177
1’i7
24.4
‘26.2
16.5
<.01
90.5
114.
13.4
<.01
By nativity of mother
Massachusetts
ElsewhereinU.S. Foreign
1,580
4111
33
182 82
14.7
43.2
35.3
<.01
93.8
120.0
117.6
)
<.01
J
By parity of mother Parity not recorded
Parity recorded
Primipara Multipara
1,43
801 2’28 573
35
17 84 88
1 .5
36.8 15.4
> 60
<
108.1
105 .8
99.9
111.5
>
>
By social class of father
Students
Warner’s class 1 and
Warner’sclass3-7
88
550
1,595
61
19
17
69.3
39.8
13.6
< .01
13.0
111.7
98.5
>05
Total ,233 497 2.3 .. 107.5 ..
TABLE II
INCIDENCE AND DURATION OF BREAST-FEEDING AMONG 33 MOTHERS
classes. An apparent correlation between social class and duration of nursing among
those mothers who did nurse was not found to be statistically significant. Because of the great association between incidence of
breast-feeding and social class, the other variables were also examined separately for each of the social class groups (Table III).
Age of Mother
For the total population (Table II) it was found that there was significant
van-ation in breast-feeding incidence by age of mother, with mothers 30 and over attempt-ing nursing less frequently than mothers under 30 (partitioned chi-square 20.99, d.f. = 1, p < 0.01). Mothers under 25 and
mothers 25-29 did not differ significanfly
in incidence of breast-feeding. For dura-tion of nursing, however, there is a change
at an earlier age, with mothers under 25 nursing for shorter periods than do older mothers (Scheffe’s test gave p < 0.01).
When the effect of age is studied for each
social group, the tendency for mothers 30
and over to nurse less frequently is found for both the upper and lower classes but not for the students. The trend for mothers under 25 to nurse for shorter periods than
older mothers is statistically significant for the lower social group, but this trend is not
statistically significant in either the students or the higher social group.
Nativity of Mother
Mothers were divided into three nativity groups-those born in Massachusetts, those born elsewhere in the United States, and
those who were foreign born. Mothers born in Massachusetts attempt breast-feeding less often than do either mothers born else-where in the United States or foreign-born mothers. This is also found for both upper
and lower social class mothers. For the total group there is a statistically significant ten-dency for mothers born in Massachusetts who do nurse, to nurse for shorter periods
TABLE III
INCIDENCE AND DURATION OF BREAST-FEEDING AMONG 33 MOThERS ACCORDING TO SOCIAL CLASS OF FATHER
‘ .
Fathers Social Class
Students Warner’s Classes 1 & S JJarner’s Cla8ses .1-7
Perceni-Total Number Mean
Number Breast- Breast- Duration Feeding Feeding (day.)
TOIIZ Number Number Breast-Feeding Percent-age Breast-Feeding Mean Duration (days) Total Numbe? Number Breast-Feeding Percent. age Breast-Feeding Mean Duraizon Byageofmotber LeuthanQ5 5_.g9 S0andover 6 4 41 17 3 P>.oo’ 66.1 77.3 75.0 P>.I5 111.0 165.7 17 Q1 55 93 71 P<.Oi 43.3 46.0 32.1 P>.25 96.7 115.8 118.1 601 451 543 97 67 53 P<.OI 16.1 14.9 9.8 P<.OI 77.8 105.0 I8.1 Bynativityofmother Massachusetts
Elsewhere in U.S.
Foreign 54 12 14 37 10 P>.40 63.6 68.5 83.3 P>.50 144.6 118.5 109.3 336 lfl 42 97 93 27 P<.Oi 8.9 53. 64.3 P>.05 98.5 H0.6 128.3 1,I 195 178 12 50 45 P<.0I 10.0 25.6 25.3 P>.0I 84.3 120.0 113.0 Byparityofmother Paritynotrecorded Parity recorded Primipara Multipara 56 32 38 23 P>.60 67.9
71.9
P>.5
115.3
135 .8 362 188 143 74 P>.75 40.1
39.4
P>.25
106.2
114.6 1,014 581 142 75 P>.50 12.9
14.0
P>.75 96.3 99.6 22 10 18 5 P>.05 81.8 50.0 P>.10 123.4 180.2 60 128 28 46 P>.10 46.7 35.9 P>.25 97.3 111.6 146 435 38 37 P<.01 26.0 8.5 P>.s0 90.7 1&2.I
Total 88 61 69.3 123.0 550 219 39.8 111.7 1,595 217 13.6 98.5
S pvalues are for differences in proportions and for differences in means as in Table II.
and although this trend persists for the upper and lower social class groups it does
not achieve the preset level of significance of 0.01 (Table III). Again the students act as a homogeneous group and no variation is found when subdivided by nativity of mother.
Parity of Mother
Information as to the parity of the
moth-ers was obtained from the birth certificates but this information was recorded for only 36% of the births. However, the incidence
of breast-feeding and the mean duration among those who breast-fed were very
similar for both those mothers whose parity was recorded and for those whose parity
was not. Even when separated by social class no variation was found for the two groups. There is thus no evidence of associ-ation between reporting of parity on the birth certificate and subsequent breast-feeding behavior.
Among the 801 mothers whose parity was
recorded, primiparas nursed significantly more often (36.8%) than did multiparas
(15.4%), but did not differ significantly in duration of nursing. When examined by
so-cial class the tendency for primiparas to
breast-feed more frequently is pronounced only for mothers in the lower social groups,
and significant variation in duration is not found for any of the groups.
Introduction of Supplementary Feeding
Among the 260 mothers who continued to breast-feed for 3 months or longer, 15% in-troduced solid food before the baby had reached one month of age and 71% had
in-troduced solids before the baby was 3 months old. The most popular introductory foods were rice cereal and applesauce.
Seventy per cent of the mothers who
nursed for 3 or more months also gave their babies milk by bottle. Forty per cent of the
mothers used a relief bottle (i.e., an occa-sional bottle given in place of a usual breast feeding), 20% used a regular daily bottle, and 10% used both a relief and a
babies, by 3 or 4 months of age, while
being nursed, were having three meals a day plus an additional evening nursing.
Thus in contrast with mothers in many de-veloping countries, American women who nurse their babies are often partial lactators only.
SUMMARY
Incidence of breast-feeding has I)een cx-amined in 2,233 women who gave birth to babies in hospitals in Boston, Brookline, and Newton in August or September, 1963. Information on breast-feeding was
ob-tained from the mothers by mailed ques-tionnaires and by telephone.
Twenty-two per cent of the mothers at-tempted breast-feeding. Five per cent of
the total population breast-fed their babies for 6 months or more.
Sex and birth weight of babies (10 not affect frequency of breast-feeding.
Social class is found to be the most im-portant variable affecting incidence of breast feeding. Women who are married to
students exhibit the highest incidence of breast-feeding (69.3%). Upper social class
women breast-feed more frequently (39.8%)
than women in lower social classes (13.6%).
Students do not show any variation in breast-feeding patterns by age of mother, parity, or birthplace, but these variables do influence the breast-feeding patterns of women in other social classes.
REFERENCES
1. Bain, K. : The incidence of breast-feeding in
hospitals in the United States. PEDIATRICS,
2:313, 1948.
2. Meyer, H. F. : Breast feeding in United States:
Extent and possible trend. Survey of 1,904
hospitals with two and a quarter million
births in 1956. PEDIATRICS, 22: 116, 1958.
3. Garland, J., and Rich, M. B. : Duration of
breast feeding: Comparative study. New
Engl. J. Med., 203:1279, 1930.
4. Davis, A., and Havighurst, R. J.: Comparison
of Chicago and Harvard studies of social
class differences in child rearing. Amer.
So-ciol. Rev., 20:438, 1955.
5. Sears, R. R., Macoby, E. E., and Levin, H.
Patterns of Child Rearing. White Plains, New
York: Row, 1957, p. 409.
6. Boek, W. E., Lawson, E. D., Yankauer, A.,
and Sussman, M. B.: Social Class, Maternal
Health and Child Care. Dittoed publications.
Albany: New York State Department of
Health, 1957, p. 103.
7. Salber, E. J., Stitt, P. G., and Babbatt, J. G.
Patterns of breast feeding. I. Factors affecting
the frequency of breast feeding in the
new-born period. New EngI. J. Med., 259:707,
1958.
8. Warner, W. L.: Social class in America. Harper
Torchbooks, First Ed., New York: Harper
and Brothers, 1960, pp. 140-141.
Acknowledgments
We wish to thank Mr. Raymond D. Lavalle, the
Registrar of Vital Statistics, Commonwealth of
Massachusetts, for access to birth certificates, Mrs.
Hazel Coven for assistance with the data
collec-tion and coding, and Mrs. Lena Wettermark and
Mr. Mark Alpert for assistance in statisticl
