Family Size of Children and Women during the Demographic Transition

This paper analyzes links between declines in the family size of women and declines in the family size of children during the demographic transition. We extend Preston’s (1976) model in two ways. First, we derive the relationship between the variance of women’s family size and children’s family size, a relationship that has important implications for inequality in children’s family size. Second, we analyze family size from the perspective of children of a given age rather than women of a given age. We apply the framework to 310 data sets from the IPUMS-International census project and the Demographic and Health Surveys, representing 101 countries. Consistent with Preston’s conjecture, we find that mean family size of children tends to fall more slowly than mean family size of women as fertility declines. The increase in resources per child is 5%-20% smaller than it would be if children’s family size decreased at the same rate as women’s family size. We show that inequality in children’s family size increases substantially as fertility declines, the result of increasing skewness in women’s family size.