Published online by Cambridge University Press: 23 May 2014
Increasing attention has been paid to population growth in the Third World. Although it is commonly held that mortality decline has been responsible for the population increases that have occurred, in many instances fertility has contributed significantly to the population increases as well. Many traditional societies have relatively high fertility rates, but they are still often below the potential maximum. Fertility in these pre-modern societies has been held in check by health conditions of the society, by prolonged breastfeeding, and by sexual restraint, particularly after the birth of a child (Lesthaeghe, 1981: 3–23). The move from a traditional to a more modern society can mean increased health care and better nutritional status, both of which may improve the health of the mother and child and lead to increased fecundity and higher fertility. In addition, the relaxation of postnatal sexual abstinence and the decrease in the length of lactation which usually accompanies this transition can lead to shorter birth intervals and higher fertility levels. The time lag between the effects of fertility-increasing factors and the changes in values and norms which favor smaller family size allows rapid population growth to occur.
Evidence for this pattern of fertility increase can be found in many Third World countries (Nag, 1981). In Africa, for example, a rise in fertility during the beginning stages of modernization has been documented in Zaire (Romaniuk, 1980), Nigeria (Olusanya, 1969), and Sudan (Henin, 1969). In each case, the rise has been accounted for through the spread of social and economic change.