Aggregating the Fertility Transition: Intergenerational Dynamics in Quality and Quantity

Fertility change is distinct from other forms of social and economic change because it directly alters the size and composition of the next generation. This paper studies how changes in population composition over the fertility transition feed back into the evolution of average fertility across generations. Theory predicts that changes in the relationship between human capital and fertility first weaken and then strengthen fertility similarities between mothers and daughters, a process that first promotes and then restricts aggregate fertility decline. Consistent with these predictions, microdata from 40 developing countries over the second half of the 20th century show that intergenerational fertility associations strengthen late in the fertility transition, due to the alignment of the education-fertility relationship across generations. As fertility approaches the replacement level, the strengthening of these associations reweights the population to raise aggregate fertility rates, pushing back against aggregate fertility decline.