SES differences in marital fertility widened during the fertility transition—evidence from global micro-level population data

The decline in human fertility during the demographic transition is one of the most profound changes to human living conditions. To gain a better understanding of this transition we investigate the association between socioeconomic status (SES) and marital fertility in different fertility regimes in a global and historical perspective. We use data for a large number women in 91 different countries for the period 1703–2018 (N = 116,612,473). In the pre-transitional fertility regime the highest SES group had somewhat lower marital fertility than other groups both in terms of children ever born (CEB) and number of surviving children under 5 (CWR). Over the course of the fertility transition, as measured by the different fertility regimes, these rather small initial SES differentials in marital fertility widened, both for CEB and CWR. There was no indication of a convergence in marital fertility by SES in the later stages of the transition. Our results imply a universally negative association between SES and marital fertility and that the fertility differentials widened during the fertility transition.