No Partner, No Children? Union Formation, Assortative Mating, and Educational Inequalities in Fertility in Germany

Education is linked to whether and with whom individuals form partnerships. However, it is largely unclear how educational differences in union formation and matching with equally, more, or less educated partners shape educational disparities in fertility. Using data from the German Socio-Economic Panel, we applied marginal structural models to investigate how higher education affects the probabilities of ever having a first and a second child, and to what extent these effects operate through union formation (having a partner or not) and assortative mating (having a highly educated partner or not). We compared women and men socialised in East and West Germany before reunification, two contexts with distinct gender and stratification regimes. Findings indicate that higher education influenced fertility directly and indirectly through partnership formation, but only marginally through partners’ education. Moreover, findings varied across contexts. In West Germany, higher education reduced women’s probability of becoming mothers but had minimal impact on second births. For men, higher education increased the probabilities of having both a first and a second child. These gendered effects emerged because higher education influenced fertility directly and indirectly via union formation. In East Germany, higher education had limited effects on fertility, except for increasing men’s second birth probabilities. These weak effects resulted from small direct effects, counterbalanced by indirect effects linking higher education and fertility through union formation and assortative mating. Our study contributes to debates about precursors to family formation, underscoring the importance of union formation as a mechanism linking education and fertility.