Coitus, the proximate determinant of conception: Inter-country variance insub-Saharan Africa

There is a general consensus in the literature that fertility differences b etween populations can be accounted for by differences in just four key pro ximate determinants: nuptiality, the postpartum non-susceptible period, con traception and abortion. Natural fecundibility is generally assumed to be c onstant between populations. This paper puts the theoretical and empirical case for a re-evaluation of that assumption, drawing on the under-utilized data on sexual activity collected in the Demographic Health Surveys (DHSs). Using data for married women in nine African countries, the analysis finds substantial population level differences in mean monthly coital frequency, which, if accurate, suggest an important demographic effect. There is a cl ear regional patterning to these differences, with levels of activity consi derably lower among women in the West African populations included in the s tudy than those from East and southern Africa. For West Africa in particula r the data indicate the normality of exceptionally long periods of very inf requent or no intercourse by married women outside the period of postpartum abstinence. The findings challenge prevailing presumptions concerning susc eptibility to pregnancy in marriage on which statistics for unmet need for family planning are derived. While doubts are raised over the precision of the sexual activity data used, the paper argues for the need for a greater effort to operationalize the 'proximate determinant of conception', not onl y for more accurate fertility modelling, but also as a planning tool for a more sensitive provision of family planning services in Africa.