Fewer Couples, Fewer Births: Decomposing the Fertility Decline

Abstract

We study the contribution of changing partnership patterns to recent fertility change. Using data for several European Union countries and the United States, we analyze fertility developments between 2005 and 2020. Applying a Kitagawa decomposition, we separate fertility changes into a composition component, i.e., shifts in partnership exposure, and a rate component, i.e.,changes in fertility within partnership statuses. We find that declines in marriage and cohabitation reduced total fertility rates in every country studied, including those where overall fertility increased. These results suggest that fertility trends cannot be understood solely as changes in childbearing behavior within unions, but also reflect a contraction in exposure to childbearing. Hence, the results highlight the importance of understanding union formation dynamics for explaining contemporary fertility change.