The Proximate Determinants of Exceptionally High Fertility

A not uncommon but simplistic view of changing reproductive behavior during the transition from high to low fertility holds that a rise in the practice of contraception is virtually the only proximate cause of fertility decline. Supporting evidence for this view of the transition in reproductive behavior includes the high degree of correlation (r=0.92) between the total fertility rate and the contraceptive prevalence level in contemporary populations. There are a number of developing countries however that have fertility rates far in excess of what one would expect on the basis of the level of contraceptive use. Clearly contraceptive prevalence is not the only proximate determinant of fertility rates. A plausible hypothesis to explain the high fertility in Yemen Kenya Syria Jordan and Zimbabwe is that marriage and breastfeeding behaviors in these societies exert less restraint on fertility than is the case in other societies with the same level of contraceptive prevalence. In each of these countries except Zimbabwe both breastfeeding and the marriage pattern exerted smaller fertility-inhibiting effects than in other societies with the same level of contraceptive prevalence and these differences account for a large part of the excess fertility. This brief review of the dynamics of fertility and its proximate determinants indicates that there is no necessary connection bertween trends in fertility and contraceptive prevalence at the onset of the fertility transition. It is quite possible for fertility to remain constant or even rise temporarily as contraceptive use increases because other proximate determinants can exert offsetting upward pressure on fertility.