desirability of being in a polygynous union by women, several papers have documented that women and children in polygynous households exhibit poorer health outcomes because of competition for resources (see Bove and Valeggia, 2009, for a review of the empirical evidence on the relationship between polygyny and women’s health in Sub-Saharan Africa).<sup>34</sup> Female headship has often, but not always, been found to be associated with poverty and insecurity.<sup>35</sup> Horrell and Krishnan (2007) find that female-headed households in rural Zimbabwe are no different from male-headed ones in terms of income poverty, but they lack assets for agricultural production and are thus constrained in their capacity to improve productivity.

# **6.1.1 Data and results**

I use the sample of all married (or ever-married) women to explore whether polygyny and other marital outcomes are associated with the sex of their first-born child. Among polygynous married women (with at least one child ever born), 43 percent are ranked first, 47 percent second, 8 percent third, and 1 percent higher rank.<sup>36</sup> The probability of being in their first union is lower for higherrank wives (89 percent for rank one wives, 69 percent for rank two, 56 percent of rank three, while it is 91 percent for women in monogamous marriages).<sup>37</sup> I analyze the effect of a first-born daughter on four separate outcomes: that the husband takes another wife (the husband is polygynous), that he lives with his wife, and that the woman is ever divorced or separated or she is the head of the household. The empirical strategy is similar to that employed in the analysis of fertility outcomes illustrated in section 4.1.<sup>38</sup> Again, the identification assumption is that the sex of the first-born is conditionally exogenous. Each regression is run separately for all married (or ever-married women), and on the subsample of older women aged 30–49, who are more likely to have experienced the outcomes under consideration.

I exploit the information on the rank of each wife in a polygynous union and run a regression in which the dependent variable is equal to one if the woman is the first-rank wife, and zero if she is monogamously married (thus excluding wives of higher order rank). This is because the outcome of interest is whether the husband marries another woman as a consequence of the fact that the first wife had daughters instead of sons. Thus, I compare monogamous women to women who are

> 34Boserup (1970) and Goody (1976) argue that the prevalence of polygyny is positively associated with the degree of female involvement in agriculture. Jacoby (1995) finds a relationship between polygyny and women’s productivity in agriculture in Cˆote d’Ivoire.

> 35see Buvinic and Rao Gupta, 1997, for a review of the literature, and van de Walle, 2013, for a study of the welfare consequences of being a widowed female head in Mali.

> 36The rank is typically based on the duration of marriage, with women ranked first as the ones married the longest.

> 37Levirate marriage (traditional practice in which the wife of a deceased man is obliged to marry the husband’s brother) is not uncommon in Nigeria.

> 38Additional controls include the number of children ever born and household size.

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