Demographic Transition in Africa: The Polygyny and Fertility Nexus

Roland Pongou, Université d'Ottawa
Paul Cahu, World Bank Group
Falilou Fall, Université de Paris I, Sorbonne

Sub-Saharan Africa is the only region of the world where the demographic transition is not completed. Though mortality has declined since the 1960s, fertility remains very high. We examine the role played by the common practice of polygyny in sustaining a high level of fertility in this region. We find that polygyny has opposite effects on individual and aggregate fertility. A woman married to a polygynous man tends to have fewer children than if she is the only wife. However, the practice of polygyny increases the number of marriages, resulting in higher aggregate fertility. Furthermore, fertility is contagious, whereby a woman, regardless of whether she is married to a monogamous or a polygynous man, tends to produce more children as fertility level in her neighborhood increases. We estimate these distinct effects using household data. These estimates further allow us to simulate the impact of polygyny on total fertility.