NOT only a direct risk to babies, the indiscriminate promotion of infant formula in the Third World also often increases women’s fertility. The result? Further damage to women and children’s health. It does this both directly — as breast-feeding has long been known to be nature’s own contraceptive — but also indirectly, as children’s early deaths encourage parents to have more.
The decline of breastfeeding in the Third World over the last thirty years is frightening. In South Korea, for example, prolonged breastfeeding fell between 1950 and 1970 from 55 to 35 per cent of first births. The figure for four week old babies who are breastfed in Brazil has dropped from 96 per cent in 1940 to 40 per cent by 1974. Perhaps the most startling figures come from Chile, where 25 years ago 95 per cent of mothers breastfed their babies for one year, while now only 20 per cent do at two months.
The fertility effect of this decline in breast-feeding has only recently been studied. Formerly little was known about the length or degree of protection from pregnancy afforded by breastfeeding, or indeed whether this was primarily due to suckling itself or to linked customs in traditional societies such as sexual abstinence.
As a result of this ignorance, when modern contraceptive technology becomes available, the emphasis was against relying on the breast. Instead artificial contraceptives were encouraged, even though most Pills are known to inhibit milk production in nursing mothers. But often artificial contraceptives were not used regularly. In Bangladesh, where breastfeeding accounts for a long natural birth interval in rural populations, there is evidence that indiscriminate promotion of the Pill meant that even breast-feeding women took it. Their milk then dried up, so they abandoned the Pill. They then had protection neither from breastfeeding nor artificial contraception. As a result women became pregnant much sooner than they would have done in normal circumstances.
This lesson learnt, family planners are now looking at exactly what kind of protection from pregnancy breastfeeding gives. The International Fertility Research Programme has started one such study in Durango, Mexico, on a small group of breastfeeding women. The area is not perfect for the study, there is no tradition of long breastfeeding and as the study supervisor Dr Bhiwandiwala wryly remarks, ‘They start on Coca-Cola very early.’ However, preliminary results show that it is not just the presence or absence of breastfeeding which counts, but the amount of suckling which takes place. Mothers who nurse often, on demand, return to fertility much later than those who do not feed at night, or who stick to regular, separate feeding intervals.
The contraceptive effect of breastfeeding comes from the release of a hormone (prolactin) directly after stimulation of the nipples, which in 5 to 15 minutes increase almost 20 times its normal level in the bloodstream. Prolactin is short-lived in the blood, however, so that half of this quantity will have vanished 10-30 minutes after suckling stops, so that regular feeding is needed to keep the level high enough to inhibit fertility. But the picture is still more complicated than that, because if a woman does ovulate, it may be what is called an ‘inadequate ovulation’, where the corpus luteum — a section of the ovary which after the release of its egg then regulates the progress of the pregnancy— does not function normally and even if the egg is fertilised, will not allow the pregnancy to continue.
A further study on this theme has been carried out among the Kung people of northwestern Botswana where there was an unusually low natural fertility — about 4.7 live births per woman, well spaced out. Children were normally weaned at three years old, and day-time suckling followed an unusual pattern — very brief— a few seconds or minutes — and very frequent When, late in the child’s second year, its playing meant longer separations from the mother, breast-feeding started to decline and fertility shortly returned.
How much can we generalise from these two examples on the contraceptive effects of breastfeeding in the Third World? The World Fertility Survey concludes that ‘on average, breastfeeding for one month adds one week to the birth interval’ — that is, six months breastfeeding adds one- and- a- half months, 1 year adds three months, and two years six. This may not seem much, but it has to be compared with the effectiveness of artificial contraception. In Bangladesh, Sri Lanka and Indonesia where breastfeeding is long— on average 29 months in Bangladesh— this adds about nine months to the average birth interval, the use of contraception added less than one month. In Jordan, Peru, Guyana, Colombia and Panama, breast-feeding added an average of five months to the length of the birth interval. Only in Colombia and Panama did artificial contraception increase the birth interval by more than the effect of breastfeeding.
In conclusion, countries like Colombia and Panama, which are heavily Westernised in the urban areas and where traditional cultures are largely eroded — aggressive Western provision and marketing of artificial contraceptives may just offset the aggressive Western marketing of breastmilk substitutes, at least as far as fertility is concerned. Elsewhere, bottle-feeding may well have increased unwanted pregnancies.