The decline in fertility in Botswana, Kenya, South Africa and Zimbabwe is in contrast with what is happening in the rest of sub-Saharan Africa. Fertility in this region is still regarded as the highest in the world and shows few signs of decline even though there is disputable evidence that fertility may have begun to decline in Senegal, Mali, Togo and Nigeria (Caldwell 1994). The total fertility rate for the continent is about 6.3 children per woman (van de Walle and Foster 1990) while it is 4.3 in Zimbabwe (ZDHS 1995), 4.9 in Botswana (BDHS 1988) and 5.4 in Kenya (KDHS 1993). The persistence of high fertility in most parts of sub-Saharan Africa has led many researchers to seek social, cultural, economic and biological explanations for the persistence of high fertility regimes (Caldwell and Caldwell 1987, Cohen 1993, Jolly and Gribble 1993, Lesthaeghe et al. 1981). However, there are very few studies that have attempted to decompose and analyze the fertility transition that has started to occur in some African countries in an attempt to identify the sources of fertility change or to establish what one might call the "components" and determinants of reproductive change. Establishing the sources or components of fertility change simply refers to an identification of where changes in fertility behavior that are specific to parity and woman's age have occurred and to establish whether the decline has been confined to certain ages and parities.