Children under five in polygynous households in Sub-Saharan Africa, 2000 to 2020.

Background: Cross-sectional analyses have identified polygyny as a prevalent family form across sub-Saharan Africa, though it has been declining over time in most countries. Yet, how the prevalence of young children in polygynous households has changed over time concurrent to changes in other demographic indicators is not well understood. Trends in polygynous living arrangements and selection into these households may have consequences for related disparities in health and mortality over time. Objective: We describe the prevalence of young children residing in polygynous households over a twenty-year period of significant social and demographic change. Methods: We analyze nationally representative household survey data from 83 Demographic and Health Surveys from 27 sub-Saharan African countries collected between 2000 and 2020. Among children under five years of age, we estimate the changing prevalence over time of residing in a polygynous household and compare to the prevalence of women of reproductive age in polygynous unions. We then disaggregate this change by maternal marital status and wife rank. Results: There is substantial variation in the proportions of young children in polygynous households across countries in the sample, though the prevalence has declined in almost all countries over time. Children have experienced a more rapid decline in almost all countries than women of reproductive age in polygynous unions. Over time, children in West Africa are shifting towards monogamous households, while children in Central and Southern Africa are becoming more likely to have a mother who is divorced, widowed, or never married. Contribution: This paper provides new estimates of the characteristics and trends over time of young children residing in polygynous households across sub-Saharan Africa.