Components of unexpected fertility decline in sub-Saharan Africa

This paper studies four sub-Saharan countries -- Ghana, Kenya, Senegal, and Zimbabwe -- in which fertility has declined by a greater amount than would be expected on the basis of increases in contraceptive prevalence. The analysis is based on the results of two surveys conducted in each country under the Demographic and Health Surveys program. Surveys in Ghana were conducted in 1988 and 1993, in Kenya in 1989 and 1993, in Senegal in 1986 and 1992/1993, and in Zimbabwe in 1988 and 1994. The study reveals that several factors have contributed to larger than expected fertility declines: the use of more effective methods of contraception; the lag effect of rapid increases in contraceptive adoption; stability in the duration of postpartum insusceptibility; and changes in marriage and sexual behavior. Also, a multivariate analysis using the survey data suggests that fertility regulating behavior not captured by the standard measurement of contraceptive use exists to some degree in all four countries. Specifically, women who want no more children and those who want to delay the next birth by at least 2 years have lower coital frequency than those who want another child soon. Further, the differences between these groups has widened over time, at least in Ghana and Zimbabwe. Finally, while no common factor explains the fertility decreases in the four study countries, the evidence shows that in Kenya and Zimbabwe, declines that began in the mid-1980s are continuing and have perhaps increased their velocity in the 1990s; it also confirms earlier, tentative indications that in Senegal and Ghana, fertility had begun to decline. Includes references. (Author abstract, modified)