The aim of this chapter is to analyze the environmental and socio-economic factors influencing fertility in five sub-Saharan African countries where fertility transition has begun in recent years (Benin, Ghana, Gabon, Kenya, and Rwanda). The analysis is based mainly on the description of the socio-economic context and the data of the Demographic and Health Surveys (DHS) in these countries. Overall, it appears that the current level of fertility remains relatively high in the five countries, the TFR ranging from 4.0 in Ghana (2008) to 4.9 in Benin (2011–2012). However, a comparison of the most recent DHS with the oldest DHS shows: (1) a decline in early and latefertility; (2) a delay in the age at first marriage; (3) an increase in modern contraceptive use; (4) a sharp decline in infertility; and (5) a substantial improvement in the level of education in women of childbearing age. The pace of progress of these indicators varied from country to country, which could be attributed to the differential in the socio-economic context of the countries studied. The decline in fertility and future changes in the age structure which would be favorable to harnessing a demographic dividend will take several decades, unless strong social policies in the education and health sectors are implemented.