Polygynous unions are on the decline in sub-Saharan Africa, although uncertainty surrounding the prevalence and characteristics of children in these households remains. Emily Treleaven and Emma Banchoff find that the proportion of children under 5 living in polygynous households has declined faster than polygynous unions across almost all countries in the region since 2000.
Polygyny – the practice of one man taking multiple wives – is a traditional family form in sub-Saharan Africa. While this type of union remains common in the region, the prevalence of polygyny has steadily declined during the past several decades, against a backdrop of rapid economic development, urbanization, and increased access to education (Chae and Agadjanian 2022). While the number of reproductive-age women in polygynous marriages in sub-Saharan Africa has declined, we know less about the status of children in polygynous households. Has the proportion of children under 5 who are growing up in polygynous living arrangements declined at a similar rate, held steady, or even increased during the same period, possibly due to differing fertility rates and demographic characteristics between polygynous and non-polygynous families? Given that family structure has significant and well-documented implications for child health outcomes and under-five mortality (Omariba and Boyle 2007; Wagner and Rieger 2015), understanding the experiences of young children in polygynous households is a pressing global health issue.
Polygyny dynamics: comparing changes in union status and children’s household structure
Our analysis of Demographic and Health Surveys (DHS) from 27 sub-Saharan African countries highlights the considerable heterogeneity in polygyny across the region, with the highest prevalence in West Africa (Treleaven and Banchoff 2024). Consistent with shifts in polygynous unions (Chae and Agadjanian 2022), the proportion of children growing up in polygynous households – so defined if any reproductive-age woman in the home self-reports being in a polygynous union – has decreased substantially over the past two decades in the majority of sampled countries.
Beyond regional and country-level differences, our analysis reveals that polygynous and non-polygynous households also differ in several key socio-demographic metrics. In general, polygynous households with young children tend to be poorer and more rural. Children in polygynous households also tend to have older parents and less educated mothers.
Figure 1 shows that between 2000 and 2020, in most countries, the proportion of children under 5 living in polygynous households declined at a faster pace than polygynous unions. This trend is especially pronounced in the Republic of the Congo, Gabon, and Mozambique. In countries where polygyny is more common, such as Senegal and The Gambia, the proportion of children in polygynous households is notably higher than the prevalence of women in polygynous unions.
The decline in polygyny has occurred in tandem with an increase in children living with single mothers (i.e., never-married, widowed, or separated). Their proportion has increased in all regions since 2000, as has the proportion of young children whose mother is in a monogamous union (Figure 2). The increase in monogamy is especially dominant in West Africa, whereas the shift towards single motherhood is more significant in Central and Southern Africa. Even within polygynous family structures, the number of wives per household appears to be shrinking, at least within Central and Southern Africa; the likelihood that a young child’s mother is a third or higher order wife has declined more than the likelihood of having a polygynous mother of first or second wife rank, suggesting a trend towards smaller polygynous families over time in this region. Polygynous households have also become less likely to include foster and adopted children across all regions, while the opposite is true for non-polygynous households.
Drivers and implications of changes to household structure:
The faster decline of children living in polygynous households relative to women in polygynous unions likely reflects a confluence of social, economic, and legal factors. As polygyny has decreased in prevalence, changes to household structure, such as a rise in the proportion of young children with unmarried mothers and a decrease in the number of wives per polygynous household, have occurred simultaneously. Polygynous households may also be experiencing changes to fertility patterns at a different rate compared with non-polygynous households, though empirically examining trends in fertility across polygynous and non-polygynous families is beyond the scope of this analysis.
Furthermore, previous research suggests that children in polygynous households are more likely to die before age five, compared with children in non-polygynous households (Adedini and Odimegwu 2017; Smith-Greenaway and Trinitapoli 2014). A relative increase in the share of under-five mortality among children in polygynous households could also be a contributing factor to the decline in the prevalence of polygynous living arrangements among children. These trends likely intersect with the policy environments in differing countries and regions, as the legality of polygynous unions may affect household organization and resource allocation (Zeitzen 2008).
Conclusion
Polygyny remains a common family arrangement in many countries of sub-Saharan Africa, although changes to polygyny, and household composition more broadly, are taking place across the continent against a backdrop of other social and demographic changes, including urbanization, increased educational opportunities for women, and a shift towards single motherhood. As children in polygynous and non-polygynous households may have differing lifetime outcomes, these changing demographic patterns may have significant policy and public health implications.
References:
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Chae, Sophia, and Victor Agadjanian. 2022. “The Transformation of Polygyny in Sub-Saharan Africa.” Population and Development Review 48(4):1125–62. doi: 10.1111/padr.12524.
Omariba, D. Walter Rasugu, and Michael H. Boyle. 2007. “Family Structure and Child Mortality in Sub-Saharan Africa: Cross-National Effects of Polygyny.” Journal of Marriage and Family 69(2):528–43. doi: 10.1111/j.1741-3737.2007.00381.x.
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Wagner, Natascha, and Matthias Rieger. 2015. “Polygyny and Child Growth: Evidence From Twenty-Six African Countries.” Feminist Economics 21(2):105–30. doi: 10.1080/13545701.2014.927953.
Zeitzen, Miriam Koktvedgaard. 2008. Polygamy: A Cross-Cultural Analysis. London: Routledge.