14th journées Louis-André Gérard-Varet

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Strategic Choices in Polygamous Households: Theory and Evidence from Senegal
Pauline Rossi

Last modified: 2015-03-10


This paper proposes a new framework to account for fertility choices in polygamous households. I specify the main drivers of fertility in the African context and I model explicitly how the fertility of one wife impacts the behavior of her co-wives. Each wife cares about her relative number ofchildren, compared to the others, while the husband cares about his total number of children with all wives. Moreover, marriage duration matters, because couples have only some imperfect control over births. I solve for the optimal fertility of wives in bigamous households using the concept of Cournot-Nash equilibrium. The model implies that the timing of successive marriages will impact completed fertility as well as birth spacing patterns. Exploiting this feature, I derive predictions to test empirically for the existence of strategic interactions. Combining original data from a household survey and the Demographic and Health Surveys in Senegal, I show that children of both wives are strategic complements : one wife will raise her fertility in response to an increase by the other wife. The reproductive rivalry between co-wives has been widely documented in the anthropology and sociology literature, but it had never been established empirically so far. By providing new insights into potential obstacles to the fertility transition, this paper has strong implications for population policies in Africa. It also contributes to the literature on household behavior as one of the few attempts to open the black box of non-nuclear households.


Noncooperative models; Polygamy; Fertility; Africa