Breast-feeding and fertility: Sociocultural factors

Znt. J. Gynaecol. Obstet., 1987, 25 Suppl: 191-206 International Federation of Gynaecology & Obstetrics

191

BREAST-FEEDING AND FERTILITY: SOCIOCULTURAL FACTORS

PREMA RAMACHANDRAN

Indian Council for Medical Research, Ansari Nagar, New Delhi 110029 (Zndk)

Keywords: Lactation; Fertility; Supplemen- tary feeds; Maternal nutrition.

Introduction

Several epidemiological and laboratory investigations have confirmed the traditional beliefs that lactation prolongs postpartum amenorrhea and provides some degree of protection against pregnancy even after the resumption of menstruation [ 12,2 11. The two crucial factors that determine the duration of this infertile period are the duration of unsupplemented lactation and the total duration of lactation [ 12,161. The results of some studies have suggested that the effects of age, parity, sociocultural factors (including socioeconomic variables; education and employ- ment status) on fertility during lactation are mainly attributable to variations in breast- feeding practices [ 12,2 11. Studies undertaken during the last decade have suggested that, in addition to breast-feeding practices [ 13,15, 171, several other factors such as maternal nutritional status [9,10,19], infant nutrition, morbidity and mortality under the existing conditions of health and nutritional care [8,12,22] may each have a role in determining the return of fertility. Available information suggests that prolactin plays a crucial role in many, if not in all, the physiological responses during lactation. Prolactin is thought to be the major factor in the initiation of lactation and in the maintenance of relative infertility during lactation [ 131. However, the role of prolactin in the maintenance of

0020-7292/87/$03.50 0 1987 International Federation of Gynaecology & Obstetrics Published and Printed in Ireland

established lactation is unclear. It has been suggested that in undernourished women per- sistently high prolactin levels during lactation may prolong the duration of relative infertility [ 43 , facilitate nutrient transfer to milk [91 and also prevent deterioration in maternal nutritional status [ 171. The physiological consequences of variations in breast-feeding practices and their impact on nutrition, fertility and mortality under the existing sociocultural milieu in different communities will be reviewed briefly in the following pages. Special emphasis will be placed on lacunae in our existing knowledge of the subject.

The duration of lactation and the return of fertility

Ample data exist to suggest that the duration of lactation is a critical determinant of the duration of lactational amenorrhea [ 12, 17,2 1 ] (Fig. 1). Conception rates during lactational amenorrhea, irrespective of its duration, are no mom than 2 - 10%. Even after the resumption of menses, continued lactation has some inhibitory effect on the return of normal menstruation and fertility.

The return of menstruation and fertility occur much more rapidly in women from developed countries and in economically advantaged segments of populations in developing countries [ 12,211 (Fig. 2). What is even more significant is that amenorrhea is longer in rural than in urban women (Fig. 3). Some of these differences may be attributable to differences in breast-feeding practices. Sched- uled feeding with four to six feeds per day is

Int J Gynaecol Obstet 25

6

I RWANDA, BANGLA DESN. TAIWAN KOKEA. PHILIPPINES INDIA

COUNTRIES

Fig. 1. Effect of lactation on postpartum amenorrhea and conception rate. @--@, Conception during lactational amenorrhea (%); O- - -9 postpartum amenorrhea in non-lactating women; M, duration of lactational amenorrhea; -, duration of lactation.

more common in developed countries than it developing countries. Demand feeding is the is in developing ones [2 11 (Fig. 4). Breast- rule and infants are fed between eight and feeding on demand is the norm even amongst fourteen times a day in poorer segments of economically advantaged women, in some the population in India (Fig. 4). The number

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5 OWC. : WHO Collokntirr mtvdy en RvoomC kdin9.

Fig. 2. Return of menstruation in lactating women.

193

L o-3 4-6 7-9 10-12 13-18 >19

DURATIDN OF LACTATlON (MONTHS)

cl URBAN

fun RURAL

100

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Fig. 3. Return of menstruation in urban and rural women (Hyderabad, India).

of suckling episodes is a determinant of plasma amenorrhea between women from developed prolactin levels [ 131 (Fig. 5). Therefore, the and developing countries. Data from the WHO greater number of suckling episodes could be collaborative study on breast-feeding [2 11 has one of the factors responsible for the observed indicated that breast-feeding at night is a rarity differences in the duration of lactational even at between birth and 2 months of age in

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&j INDIA URBAN ELITE

a INDIA URBAN POOR

DEMAND SCtiEDULE ND. OF FEEDS ND. DF FEEDS FEEDING FEEDING BY DAY BY NIGHT

s OUKC : WHO Colloborotive study on Bnott fading

Fig. 4. Breast-feeding practices at O-2 months.

Int .I Gynaecd Obstet 25

194

2 L 6 8 10 12 1L 16 16 20 22 2L 26 26 30

WEEKS FROM DELIVERY

Fig. 5. Basal prolactin and feeding patterns in lactating mothers (n = 14) (Edinburgh, U.K.). Changes (mean+S.E.M.) postpartum in serum levels of prolactin (log normal) suckling frequency and duration, and the number of supplementary feeding in 14 breast-feeding women. Source: Ref. 13.

38 28 26 2 24

zj; x 18 F 16 s 14 2

12 10 8

7-3 10-12 N-14

DURATION FOR WHICH THE INFANT WAS SOLECY BREAST FED f YONTIIS)

Fig. 6. Effect of introduction of supplements to infants on duration of lactation, lactational amenorrhea and inter-pregnancy interval (Hyderabad, India).

developed countries, whilst infants are fed two or three times a night in many developing countries (Fig. 4). Prolactin levels have been shown to be higher in mothers whose infants suckle frequently during the day and night than in women whose infants suckle less often [4,12,13]. It is possible that suckling episodes and the consequently elevated prolactin levels at night might be another factor for the observed differences in the duration of lactational amenorrhea in developed and developing countries.

The effects of introducing supplementary feeding on the duration of lactational amenorrhea

Available information suggests that the duration of unsupplemented lactation may be a major factor in determining the duration of lactational amenorrhea. Results of investigations in Hyderabad, India indicate that the return of menstruation occurred within 2-4 months after the introduction of food supplements (Fig. 6). Usually, the introduction of


supplements results in a reduction in both the number of suckling episodes and in the total duration of suckling. Elegant longitudinal studies carried out in Edinburgh indicate that this, in turn, results in a rapid decline in prolactin levels, and inevitably in the rapid return of menstruation [ 131 (Fig. 5).

It has been suggested that if supplements are introduced between feeds, the reduction in the number of suckling episodes and the associated fall in prolactin levels could be averted. There is, at the moment, no hard data to verify this theory. However, some of the studies by the Edinburgh group indicate that the immediate impact of supplements was more on the duration of suckling, rather than on the number of feeds given (Fig. 5) [ 131. Some of the observations in high income group women in Hyderabad, India, who feed the baby on schedule, tend to suggest that the baby may not be hungry at the time of regular feed if complimentary supplements are given between feeds; the baby will either refuse the normal feed, or the duration of suckling will be considerably reduced. This might imply that a supplement may act as a substitute if the infant is not hungry. This could also imply that even if an attempt is made to introduce supplements in between feeds, a faster return of fertility can not be prevented.

In traditional poorer segments of populations from developing countries, where demand feeding is the rule, it is extremely difficult to collect information on the impact

195

of supplementary feeding on the frequency or on the duration of suckling. However, available data suggest that even in this group, the return of fertility is faster following the introduction of supplements (Fig. 6). Plasma prolactin levels were seen to be lower in women who had already introduced supplements (Table I). Two other interesting points emerged from some of the material from Hyderabad, India. The early introduction of supplements was associated not only with a faster return of menstruation but also with a shorter duration of lactation (Fig. 7). Undue delay in the introduction of supplements, however, did not result in the indefinite postponement of the return of menstruation and fertility (Fig. 6). In view of the obvious nutritional and fertility implications, further studies need to be undertaken to explore these findings.

The effects of maternal nutrition on breast- feeding practices and on the return of fertility

During the last decade, several studies attempted to evaluate the role of maternal nutrition on breast-feeding practices and on the return of fertility. Ample data exist to indicate that undernourished women in developing countries lactate successfully, and that maternal undernutrition is not associated with an alteration in the quality or quantity of milk produced in terms of proximate prin- ciples [ 5,201.

There are, however, many case reports in

Table 1. Prolactin levels in relation to breast-feeding practices. Values are mean ? S.E.M. Figures in parentheses indicate number of women.

- Breast-feeding practice: Prolactin levels (rig/ml) Total duration of lactation (months) <3 4-6 .6

Solely breast-fed 61.6 + 12.84 63.5 t 8.37 79.5 218.63 67.7 26.50 (9) (1% (7) (35)

Partly breast-fed 47.4 + 8.23 51.5 t7.67* 43.0 t 5.73* 46.1 +18.36* (6) (5) (11) (22)

*P < 0.01 as compared to soley breast-fed (t-test).


196

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0 TOTAL DURATION OF LACTATION

- L3 4-b 7-9 lo-12 13-18 19-24 325

DURATION FOR WHICH INFANT WAS SOLELY BREAST FED

(MONTHS\

Fig. 7. Effect of introduction of supplements to infants on duration of lactation (Hyderabad, India).

the literature of lactational failure associated with lower dietary intakes in well nourished women in developed countries (intake well above 2000 kcal/day). These findings are usually taken as an indication that lower dietary intake is a likely cause of lactational failure. But the possibility that lactational failure removes the need for higher food intake, and that this in turn leads to a reduction in dietary intake cannot be ruled out. There is a traditional belief in developing countries that women who weigh more do not lactate as well as their leaner counterparts. Some studies in India have suggested that low income, urban women who weigh more than 55 kg

(mean height 150 cm) tend to lactate for shorter period than thinner women (the groups cf women had similar socioeconomic, educational status and traditional breast-feeding practices) [ 15,171 (Fig. 8).

The difficulties in evaluating the effect of maternal nutrition on breast-feeding practices are compounded by conflicting data on the effects of dietary supplements on the women. Some studies indicate that there is some improvement in the quantity of milk, but most of the studies fail to demonstrate any changes either in the quantity or quality of breast milk.

There has been speculation that the return of menstruation during lactation may be delayed in undernourished women. It is, however, difficult to draw any definite conclusions from many of the earlier investigations in this area. This is largely because of the existence of confounding factors - differences in socioeconomic status, in working conditions, in breast-feeding practices and health and nutritional intervention.

The results of some recent investigations in India suggest that amongst women of similar socioeconomic status in whom breast-feeding practices were similar, lactational amenorrhea was longer in women with lower body weight for any given duration of lactation (Fig. 9) [ 171. Studies on the effects of food supplementation in lactating women in the Gambia showed that even though food supplements did not result in any change in the quantity of milk output, there was a significant fall in plasma prolactin levels and a faster return of menstruation [ 9,101.

These data imply that improvement in maternal nutritional status may lead to a faster return of fertility in lactating women. Under these conditions, and if adequate contraceptive care is not provided, the early advent of the subsequent pregnancy may negate all the benefits of the nutritional supplements. It is, therefore, essential that efforts to improve the health and nutritional status of lactating women should be integrated with the services providing contraceptive care.


197

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MEAN DURATION OF LACTATION

MEAN DURATION 3F LACTATIONAL AUENORRHOEA

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BODY WEIGHT I KQS)

Fig. 8. Effect of body weight on duration of lactation and lactational amenorrhea in Indian women (Hyderabad, India).

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Fig. 9. Effect of body weight on duration of lactational amenorrhea in Indian women from low income groups (Hyderabad, India). (1) Lactation 12-18 months. (2) Lactation 19-24 months.

ht .I G’vnaecol Obstet 25

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The effects of existing breast-feeding practices on fertility during lactation in different communities

In many developing countries, there is a tradition against feeding colostrum, and suckling is allowed only when 24-72 h have elapsed since delivery. The reason for this widespread tradition is not known, and considerable efforts are being made to counteract this practice so that the infant will have the benefit of ingesting this unique fluid. It is interesting to note that in spite of this tradition - which results in a 24-72 h delay in the initiation of suckling, there is no problem in the successful subsequent initiation and continuation of lactation in these societies. In contrast, the hospital practice of separating the mother and her infant in the first 1 or 2 days after delivery, and a delay in initiating suckling are thought to be the major factors responsible for the decline in the successful initiation and continuation of lactation in developed countries. Undoubtedly, suckling is a vital factor in the successful initiation of lactation, and the fact that the infants are fed with breast-milk substitutes during the first crucial day, or so, of life is an important factor responsible for the failure of lactation. Data from traditional societies suggest that successful lactation can be initiated as late as 48 h after delivery, when the necessary social support and encouragement are given.

Variations in the traditional patterns of introducing supplements during breast-feeding are even more marked than variations in the opinions of nutritionists about optimal supplementary feeding practice. Data from some of the studies on the effects of variations in the patterns of introducing supplements to infants upon the return of fertility during lactation reveal several interesting health, nutrition and fertility interactions.

In some parts of Africa, the tradition is to start giving chewed cassava or grains to the infant right from the neonatal period. In-depth studies in these women show that such an introduction does not have any effect on the

amount of milk secreted, nor on the duration of lactation or lactational amenorrhea [6]. At first sight, it would appear that this pattern of early introduction of a supplement does not cause a faster return of fertility. But it is possible that the introduction of such a supplement may be associated with an increased incidence of morbidity due to infections, and thus increase the infant mortality rate [ 111. The death of the infant and the cessation of lactation is, of course, associated with a rapid return of fertility.

The majority of women from developed countries and from middle and upper income groups in developing countries start introducing breast-milk substitutes, or semi-solid foods, from about the third month [21]. Investiga- tions on the “inadequate breast milk syn- drome” suggest that milk output and the growth of infants in these women are com- parable to those who consider their milk to be sufficient. It is possible that in spite of theor- etical predictions to the contrary [ 191, breast- milk alone is sufficient to support adequate growth in the majority of infants (though not in all) up to the age of 6 months [ 1,3,21]. From a nutritional viewpoint, the introduction of supplements may, in fact, not be necessary in the majority of cases up to 6 months of age. However, the introduction of supplement to infants in this segment of the population is not associated with any deleterious effect either on infant growth or on survival [ 141. The introduction of supplements usually results either in a reduction in the number of feeds or in a reduction in the duration of suckling, and is associated with a prompt fall in plasma prolactin and the return of fertility [ 131. In developed countries and amongst the economically advantaged segments of the population in developing countries, the small family norm is well accepted and contraceptive use is widespread [ 121. Therefore, although menstruation and fertility return earlier, the advent of the next pregnancy is prevented by contraceptive use.

The results of studies undertaken in the poorer segments of urban populations, espe-

Znt J Gynaecol Obstet 25

cially in the overcrowded slums in metro- politan cities, and even in some rural areas in developing countries indicate that traditional breast-feeding practices have been eroded [ 121. Two major factors are thought to be responsible for this. Bottle feeding and early introduction of processed supplements have been accepted as a symbol of sophistica- tion. Women often work as unskilled laborers in factories and there are no facilities to keep the infant in these work places. The introduction of bottle feeds and of supplements results, as expected, in reduced suckling and in a shorter period of relatively infertile lactational amenorrhea. Since processed supplementary foods and infant milk formulae are expensive, these women may over-dilute the product and, as a result, the infant does not receive adequate nutrition to support growth. The poor environmental hygiene and insanitary conditions in which the feeds are prepared, stored and fed to the infant inevitably lead to increased morbidity due to infections [2]. Infections aggravate the already existent undernutrition [2] and result in increased infant mortality (Fig. 10) [ 141. The death of

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the infant and the cessation of lactation result in a prompt return of fertility and often the start of the next pregnancy. Thus, the early introduction of supplements to infant by the poorer segments of the population in developing countries leads, on one hand, to an increase in infant mortality and, on the other, to a faster return of fertility and an early subsequent pregnancy [ 141.

In the more traditionally inclined urban poor in India, the introduction of semi-solid supplements usually begins by about the seventh month after birth. Often, well cooked mashed adult food is gradually introduced. Although these infants weigh less than their western counterparts at any given age, they triple their birth weight by the fust birthday (Fig. 11). Infective episodes occur (Fig. 12), but since the food given is freshly cooked, the chances of morbidity due to infections appear to be lower than in those infants who are fed on specially cooked weaning foods which may be kept for long periods and which often con- tain considerable pathogenic bacteria.

With this kind of traditional practice - the gradual introduction of adult food - the

‘.’ BREAST - FED R 00

PARTIALLY BREAST-FED

I!2 :r BOTTLE _ FE@

4 WEEKS 3 MONTHS 6 MONTHS

Fig. 10. Mortality rates during the first year of life in breast-fed, partially breast-fed and bottle-fed infants, among those sunriving

at 4 weeks, 3 and 6 months (rural Chile: 1969-1970). Source: Ref. 14.

Int J Gynaecol Obstet 2.5

Fig. I I. Growth of urban infants and children in relation to breast-feeding practices (Hyderabad, India).

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return of menstruation occurs 2-3 months after the initial introduction of supplements. Usually, the duration of lactational amenorrhea varies between 6 and 12 months, and inter-pregnancy intervals are between 24 and 30 months (Fig. 13). Under the conditions in which the poorer segments of the population in developing countries live, it would appear that this practice may be associated with better infant growth, lower morbidity due to infection and mortality during infancy, and with a reasonably long inter-pregnancy interval in the absence of any contraceptive use.

In some developing countries, rural women tend to delay the introduction of supplements until the infant is 1 year of age. Breast milk alone is insufficient to support infant growth until 12 months of age, and so marked growth retardation is often observed in these infants (Fig. 14). A delay in introducing supplements until the infant is 1 year of age brings a further problem. A l-year-old child is often unwilling to accept the newer varieties of food which the mother tries to introduce, and often stub- bornly sucks at the breast. Refusal to take

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supplements results in the aggravation of the already existing undernutrition. An inevitable fall in milk output beyond 1 year adds to the nutrient gap.

Undernutrition is associated with immune depression and this puts the infant at risk of infections, especially in the unsatisfactory environmental conditions in which they live (Fig. 15). Morbidity due to infections aggra- vates undernutrition and the vicious cycle, once established, often ends in the death of the infant.

The fertility consequences of the practice of prolonged, unsupplemented lactation is unsatisfactory. Although lactation is a critical determinant of the duration of lactational amenorrhea, undue delay in introducing supplements does not postpone indefinitely the return of menstruation and fertility (Fig. 16). The higher level of morbidity and mortality arising from undernutrition and infection also result in infant death. Prompt return of fertility occurs following an infant death. Thus, there is an increase in infant and young child mortality and an earlier return of fertility.

DURATION OF LACTATION I MONTHS)

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Fig. 13. Effect of duration on lactation on lactational amenorrhea and inter-pregnancy interval (Hyderabad, India).

Int J Gynuecol Obstet 25

I I

I I I I I I r 6 6 10 12 13-15 18

AGE IMOITHS)

Fig. 14. Urban-rural differences in growth of breast-fed infants (Hyderabad, India).

q -

43 4-4 7-9 lo-12

AGOC (Mwll5) Fig. 15. Prevalence of infective morbidity in relation to age in rural infants (Hyderabad, India).

Znt J Gynaecol Obstet 25

Infant mortality and fertility during lactation

In developing countries, especially in rural areas, the infant mortality rate can be between 100 and 150 deaths per 1000 births. The death of the breast-fed infant is obviously one of the major factors responsible for the cessation of lactation and its fertility consequences. Efforts to improve the health and nutritional status of infants, improvements in sanitation, provision of protected water supply, immunization and delivery of health care services to sick infants will contribute considerably to reducing levels of infant mortality. Such reductions will result in continued lactation, and indirectly, in a delay in the start of the next pregnancy.

The next pregnancy is yet another factor responsible for the termination of breast-

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g 16’

g F 14-

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Fig. 16. Effect of time of introduction of supplements to infants on duration of lactational amenorrhea (Hyderabad, India).

feeding in poorer segments of the population in rural areas. The belief that breast milk is no longer suitable for the infant once another pregnancy has occurred, and the fear that breast-feeding may be harmful to the fetus in utero are widespread in many communities. The advent of the next pregnancy may have a profound effect on infant nutrition, health and survival - as shown by classical, clinical descriptions of kwashiorkor in African countries. The initiation of suitable contraceptive measures for lactating women at the appropri- ate time will assist in ensuring continued breast-feeding and nutritional support of the infant.

203

The effect of sociocultural factors on breast- feeding practices and on fertility during lactation

The studies on breast-feeding practices have demonstrated that socioeconomic (Fig. 17) and educational status (Fig. 18) to a large extent determine the pattern of breast-feeding, and consequently fertility during lactation. In developed countries during the last few years, there has been a trend among the educated, elite segments of the population towards an increasing acceptance of breast-feeding - especially unsupplemented, demand feeding - during the first 6 months of infant life [ 12, 2 11. As a result, the duration of lactational amenorrhea is longer in these women relative to others amongst whom bottle-feeding is still common and prolonged, unsupplemented lactation a rarity. In developing countries, a reverse trend is observed among the urban elite. These women, if they successfully initiate lactation at all, tend to introduce supplements at 2-3 months of age and seldom breast-feed

I -

INCOME PER MONTH (RUPEES )

Fig. 17. Effect of economic status on duration of lactational amenorrhea (Madurai, India).

Int J Gvnaecol Obstet 25

I I -

ILLITERATE PRIMARY SECONDARY TECHNICAL COLLEGE

SCHOOL SCHOOL TRAINING EDUCATION

EDUCATIONAL LEVEL.

Fig. 18. Effect of educational status on duration of lactational amenorrhea (Madurai, India).

their infants for longer than 12 months [ 12, 2 11. It is hardly surprising that this group experiences a rapid return of menstruation (Fig. 2) [ 2 11. But with the widespread use of contraception by all segments of the population in developed countries and by the urban elite in developing ones, the fertility consequences of these poor breast-feeding practices are offset [21 I.

The poorer traditional segments of the urban and most of the rural populations in developing countries observe the socioculturally accepted norm of a traditional pattern of prolonged breast-feeding. The strongest evidence of the importance of psychosocial influences on breast-feeding practices is the fact that successful initiation and continuation of lactation for a period of 18-24 months occurs in almost 100% of women in these areas; and that this occurs despite the widespread prevalence of undernutrition, ill health and many other adverse factors [ 12,2 11. There is ample evidence to show that this traditional practice not only has a vital role in reducing infant

mortality, but also in prolonging the inter- pregnancy interval. It has been estimated that, in 1973, breast-feeding alone provided some 34 million couple-years of protection in developing countries (China excluded) compared to 27 million couple-years provided by Government and privately sponsored family planning programs [ 181. There is the added advantage that the protective effect is most obvious in illiterate, indigent, rural women amongst whom contraceptive acceptance is very low [ 161.

One of the most important sociocultural factors that has to be taken into consideration concerning fertility during lactation is the set of traditional taboos associated with intercourse during lactation. In some traditional societies, abstinence is mandatory during lactation, and this practice contributes towards extending the inter-pregnancy interval. In societies where there are no such taboos on intercourse during lactation, two distinct trends are observed. Some women continue to breast-feed their infants for prolonged periods


with the belief that this will result in the postponement of the next pregnancy. Others avoid coitus, believing that the start of the next pregnancy will curtail lactation. These beliefs and practices are not readily brought out during routine enquiries, but are of vital importance in understanding the relationship between breast-feeding practices and fertility during lactation as measured by interbirth intervals in traditional societies.

Discussion

It is obvious that there are still many lacunae in our knowledge about the interactions between breast-feeding practices and their implications for health, nutrition and fertility. To a large extent this is inevitable because interest in and research on this highly compli- cated topic began only within the past one or two decades. “Research in spite of impressions to the contrary is not an organized process of asking a question, developing methods to find the answer and reaching clear cut conclusions. Often steps are uncertain, false trails are followed, obvious opportunities missed and conclusions are often no more than hopeful guesses” [7]. When all these factors are con- sidered, it is astonishing that so much progress has been made.

The interactions between lactation, infant nutrition and mortality, maternal nutrition and fertility vary not only from country to country but also from one segment of the population to another within the same country. At the moment, we do not have adequate information on these interactions in different situations. It is possible that some existing breast-feeding practices are in fact harmful. But it is also possible that others may have evolved by trial and error over millenia, and are in fact best suited for the population under the prevailing conditions.

Ample data demonstrate that breast-feeding practices not only influence infant nutrition, morbidity and mortality but also have profound effects on maternal nutrition and fertility. Maternal nutritional status has some

205

effect on the return of fertility. Attempting to alter existing practices without understanding these interactions may result in the expected benefit not occurring - as shown by the absence of weight gain in undernourished lactating women after food supplementation. At times, attempts to alter practices may result in obvious adverse effects, such as an earlier return of fertility as the result of the early introduction of infant food supplements. If these interactions are taken into consideration when planning and implementing intervention strategies so that nutrition, health and contraceptive services are provided as a part of an integrated package, it is possible that the dividends in terms of improvements in maternal and child health and reductions in family size may be more impressive. In view of the health, nutritional and fertility implications of breast-feeding practices, it is essential that well planned and funded research is undertaken to provide additional information on these interactions.

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1

2

3

4

5

6

10

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16 Prema K, Philips FS: Lactational amenorrhea - a survey. Indian J Med Res 71: 538, 1980.

17 Prema K, Naidu AN, Neelakumari S, Ramalakshmi BA: Nutrition fertility interactions in lactating women of low income groups. Br J Nutr 45: 461,198l.

18 Rosa FW: Breast feeding in family planning. PAG Bull 5: 5,1976.

19 Waterlow JC, Thomson AM: Observation on the adequacy of breast-feeding. Lancet ii: 238, 1979.

20 Whitehead RG, Paul AA, Rowland MG: Lactation in Cambridge and in the Gambia. Proc Paediatric Conf of Royal College of Physicians (ed BA Wharton). Pitman Medical, London, 1980.

21 WHO Collaborative Study on Breast Feeding. Contem- porary Patterns of Breast-Feeding. WHO, Geneva, 1981.

22 Wyon JB, Gordon JE: The Khanna study. Population problems in rural Punjab. Harvard University Press, Cam- bridge, Massachusetts, 1971.

Address for reprints:

Dr. Prema Ramachandran Deputy Director General Indian Council for Medical Research Ansari Nagar New Delhi 110029 India


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Breast-feeding and fertility: Sociocultural factors