A widely used demographic model of fertility, based on the proximate determinants, is described. The model is fitted for three contrasting sub-Saharan African countries, using data from the 1980s round of Demographic and Health surveys, to establish a baseline profile of fertility for the period immediately before any widespread behavioural changes in response to the spread of HIV can plausibly have taken place. Regional variations in the relative significance of the different proximate determinants are noted, and considered in a discussion of the mechanisms through which HIV could influence future fertility levels. It is tentatively suggested that severe HIV epidemics are most likely to exert a downward pressure on fertility. More empirical data are required to test this theory.