Nature's contraceptive / by Iqbal Shah and Jitendra Khanna

'' Nature's contraceptive" In spite of its apparently reduced prevalence in modern times, breastfeeding still prevents more pregnancies than any other contraceptive method, particularly in the developing countries by lqbal Shah and Jitendra Khanna Considering that the world's po-pulation notched up the five billion mark in July 1987, it is hard to imagine that our nomadic an- cestors probably had the lowest rate of reproduction among all living mammals. It is believed that one of the factors that contributed to this re- markably low fertility rate was pro- longed breastfeeding, the contracep- tive effect of which, along with other factors, gave rise to an average inter- val between two consecutive births of some four years. Over the millennia, changes in life- style from hunter-gatherer to a settled rural, and now urban, way of life have - inter alia - led to a decline in the proportion of women breast- feeding their children and to a re- duced duration ofbreastfeeding. The resulting gradual erosion of the con- traceptive effect, has contributed to reduced birth intervals. Paradoxically, in spite of its apparently decreased prevalence in modern times, breast- feeding still prevents more pregnancies than any other contraceptive method, particularly in developing countries. It is not surprising, then, that breastfeeding is sometimes called "Nature's contraceptive." Unlike other so called "natural" methods of fertility regulation, the contraceptive action of breastfeeding does not de- pend on such "unnatural" things as measurements of body temperature to determine the time of ovulation or calculation of menstrual dates, as is the case with the calendar method of periodic abstinence. Intensive breastfeeding, on the other hand, naturally stops the dis- charge of eggs from the ovaries, 10 which is commonly experienced as a delay in the return of menses after the birth of a baby. The obvious draw- backs are that, for breastfeeding to produce a contraceptive effect, a suc- cessful pregnancy and suckling are essential prerequisites, and that it is not possible to predict when the con- traceptive protection might cease. So in terms of fertility regulation, breastfeeding is seen as a birth-spac- ing method rather than as a contra- ceptive method per se. Interesting evidence in support ofthis has come from a study in the Kung hunter- gatherers of Botswana, who have a low fertility of some 4. 7 births per woman without abstinence or contraceptive use. The typical weaning age was found to be later than three years. Furthermore, day-time nursing ses- sions were mostly brief - a few se- conds to a few minutes - but frequ- ent. It is believed that this nursing pattern largely contributes to the average birth interval of 44 months among these people. Certain other populations in deve- loping countries also achieve long birth intervals by prolonged breastfeeding. A burgeoning family in a Latin Ameri- can slum. Breastfeeding still prevents more pregnancies than any other con- traceptive method. Photo WHO/UNICEF/R. Mera W oRLD HEALTH, November 1987 For example, the average birth inter- val in rural Bangladesh is 33 months, which can be primarily attributed to the average lactation period of 19 months found there. The average pe- riod of absence of menses as a result of this long lactation period is 17 months. Similar intervals have been found in rural communities of Java, Senegal and Nigeria, and in many other traditional societies that do not, as yet, use modern contracep- tives but do practice prolonged breastfeeding. The sooner the menses return after a birth, the shorter the birth in- terval is likely to be, assuming that the woman is sexually active, there are no miscarriages and no contra- ceptives are being used. It has been found that in women who do not breastfeed, the menses usually re- turn within two to three months after delivery. But in those who breastfeed intensively for one or two years, the menses generally return within 6 to 10 months or 15 to 18 months, re- spectively. These are average figures and of course do not necessarily apply to individuals. It appears that the ideal way of pro- longing the birth interval would be by combining prolonged breastfeed- ing with the commencement of con- traceptive use at the appropriate time, provided this time were known. A particularly important advantage of this approach is that part of the birth interval would be prolonged natural- ly, (that is, without any burden of con- traceptives, some of which are known to reduce milk production), not to mention the innumerable benefits for the nursing child in terms of bet- ter and safer nutrition, protection from diseases and so on. Unfortun- ately, this combination ofbreastfeed- ing followed by the use of a contra- ceptive is not often seen. The popula- tions that use modern contraceptives rarely rely on prolonged breastfeed- ing to increase the birth interval, and conversely, those who practice prolonged breastfeeding rarely use contraceptives. In the absence of contraceptive use and breastfeeding the birth interval averages 16 months, but with pro- longed and intensive breastfeeding it could potentially be extended by a further 18 months, giving an average interval of 34 months. (It should be borne in mind that the birth interval includes the nine-month period of the next pregnancy.) This implies that the fertility of those who do not W oRLD HEALTH, November 1987 A plump baby still on the breast in Bangladesh. Many mothers know that nursing a baby helps postpone the next pregnancy. Photo WHO/UNICEF/A Khan breastfeed (and do not use contracep- tives) could be halved by breastfeed- ing alone. But it has been observed that most of the women who in the process of "modernisation" choose not to breastfeed, or who have re- duced its duration, do not simulta- neously start using contraceptives; so their fertility can be potentially double what it might have been if they had continued with the tra- ditional, prolonged breastfeeding practices. This tendency for fertility to in- crease during the early stages of mo- dernisation is seen in countries such as Kenya, Nigeria, Sudan and Zaire, as well as in certain others in Asia and Latin America, where the trend away from a tradition of prolonged breastfeeding has not been accompa- nied by increased use of modern con- traceptive methods. In Africa and most of Asia, breastfeeding is still a dominant factor in keeping fertility in check, whereas contraception has be- come the important determinant in Latin America, where fewer women breastfeed and the duration is shor- ter. With regard to modernisation, it should be noted that it is probably as much out of compulsion (separation of the mother from the child owing to work and so forth) as it is out of ignorance and the desire to be "modern" that women give up the traditional practices. While it is widely known that nurs- ing a baby helps postpone the next 11 "Nature's contraceptive" Midday meal for a small child in Boli- via. Many cultural and religious prac- tices relate to weaning -the age when it should be started and what foods should be given. Photo WHO/UNICEF/R. Witlin pregnancy, practices and beliefs vary by region and ethnic group. Socially sanctioned durations of breastfeed- ing are usually prolonged in traditi- onal societies, and it is rare to find a woman in such communities who re- ports that she was unable to nurse her own child. The "appropriate" time to wean is usually determined either by the return of the menses, by the child's physical development or at- tainment of a particular age, or by the onset of pregnancy. Whereas in some cultures, women breastfeed until they become preg- nant again, elsewhere there are strong taboos against conceiving while an infant is still breastfeeding. This is the case in traditional societies of sub-Saharan Africa and in some other communities to ensure that the 12 baby at breast is not weaned prema- turely by the onset of a new pregnan- cy. These societies have, or have had, taboos on post-partum intercourse as long as the child was being breastfed. A belief common to the rural areas of both Java and tropical Africa is that "the semen damages both the quality and the quantity of the mother's milk and thus the health of the child who is being breastfed is endangered." A study in rural Java revealed that 60 per cent of women felt that "abstin- ence should continue at least until weaning." Many other cultural and religious practices relate to weaning, including the age at which it should be started and the types of supple- mentary food given. Beliefs reinforcing breastfeeding were common but there has been a gradual erosion in modern times . Available evidence suggests that the duration of breastfeeding is declin- ing, at a varying pace, throughout the developing world. In countries such as Korea, Malaysia and Singapore, where modernisation has occurred during a relatively short space of time and where data are available for that period, the decline in breastfeeding has been rather substantial. General- ly within individual countries, we find shorter durations (and lower pre- valence) of breastfeeding among younger women, those with higher education, and those from upper socio-economic levels and living in urban areas than among older women or those who live in rural areas, are of lower socio-economic level and are less educated. As we have seen, breastfeeding de- lays the return of fertility by suppres- sing ovulation (the release of eggs from the ovaries), although exactly how this happens still remains a mys- tery. What is interesting is that the key factor appears to be the stimula- tion of the nerve endings in the nipple and the surrounding area ef- fected by the infant's sucking of the nipple, causing the secretion of at least three hormones from the pituit- ary gland, which is situated in the brain. Two hormones (prolactin and oxytocin) are secreted in increased quantities, while a third (luteinising hormone) is released in less than nor- mal quantity. Prolactin and oxytocin mainly act on the breast, but may also have some action on the ovaries. The former stimulates the production of milk and the latter the release of it. Luteinising hormone is known to be required for the normal development of the eggs and their release from the ovaries. Thus, by frequent suckl- ing, a mother can ensure a continu- ing supply of milk and, at the same time, postpone the restoration of her fertility. The WHO Special Programme of Research, Development and Re- search Training in Human Reproduc- tion has for a long time been involved in the study of natural methods of fertility regulation, keeping in mind the needs of populations where the acceptability of other methods is low for religious or other reasons, and of people who do not yet have easy ac- cess to modern contraceptives. But as noted earlier, there are differences among populations with regard to breastfeeding patterns and the timing of return of fertility. Therefore, in order to be able to give sound advice on this issue to family planning pro- grammes, it is important that WHO continues to study breastfeeding in different ethnic and social groups and, simultaneously, to conduct research into the mechanism of "nature's birth-spacing method". • WoRLD HEALTH, November 1987