Revisiting the Polygyny–Fertility Nexus in Sub-Saharan Africa: The Role of Marital Dynamics

Xinyi Zhao , Max Planck Institute for Human Development
Ben Malinga John, University of Malawi

Polygyny remains a salient feature of marital systems in sub-Saharan Africa (SSA), where cultural norms and demographic structures have historically sustained its practice. Although prior research has documented lower fertility among women in polygynous unions relative to those in monogamous ones, these associations may reflect the confounding influence of marital instability and remarriage. This study re-examines the polygyny–fertility relationship by incorporating marital dynamics and assessing whether remarriage moderates the fertility outcomes associated with polygyny. Using nationally representative samples of women aged 15–49 from the most recent Demographic and Health Surveys (DHS) in 23 SSA countries, we estimate survey-weighted quasi-Poisson regression models for each country to assess cross-national variation in the effects of polygyny and remarriage on fertility. In contrast to the commonly reported negative association between polygyny and fertility, our results reveal substantial cross-national variation in these relationships across SSA, after controlling for individual socioeconomic characteristics. Moreover, these associations are shaped by women’s marital histories. Among women in intact unions, polygyny tends to be positively or neutrally associated with fertility, whereas among remarried women, the effects are weaker, often statistically insignificant, and in some cases reversed relative to those in monogamous unions—as observed in Sierra Leone and Burkina Faso. These findings indicate that marital trajectories condition the fertility implications of polygyny and that the fertility-depressing effect of polygyny is amplified among remarried women. By integrating marital history into cross-national analyses, this study refines our understanding of how union dynamics structure reproductive behavior in contemporary SSA.

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 Presented in Session P3. Families, Fertility, and the Life Course 3