Children under 5 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 proportion of young children residing in polygynous households over a 20-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 5 years of age, we estimate the proportion residing in a polygynous household over time and compare it to the proportion of women of reproductive age in polygynous unions over time. We then disaggregate this change by maternal marital status and wife rank. Results: Despite substantial variation between countries in the sample, the proportion of young children in polygynous households declined almost universally in sub-Saharan Africa from 2000 to 2020. The proportion of children in polygynous households declined more rapidly than the proportion of women of reproductive age in polygynous unions in almost all countries. Children in West Africa are increasingly living in monogamous households, while children in Central and Southern Africa are 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.