The Social Gradient in Infant Health from a Couple-Level Perspective: Revisiting the Heterogamy Penalty Hypothesis

Sandrine Metzger , University of Vienna
Nadia Steiber, University of Vienna
Anna Baranowska-Rataj, Umeå University
Laura Zilian, University of Vienna

This study examines the consequences of educational assortative mating for infant health. Although the positive relationship between maternal education and infant health is well-established, less is known about the impact of both parents’ absolute and relative education. Yet, the heterogamy penalty hypothesis suggests that couples with dissimilar educational status face greater stressors than their homogamous counterparts, potentially resulting in unequal gestational outcomes between pairings. Using Austrian birth register data (N=455,191 singleton births; n=355,119 different-sex couples), we apply Diagonal Reference Models to disentangle the independent association of educational dissimilarity with infant health from each parent’s educational levels to test this assumption. Results indicate a pronounced couple-level educational gradient, with substantially better birth outcomes among higher-educated homogamous parents, as well as a relatively balanced contribution of maternal and paternal education in shaping infant health. While hypogamy shows no significant disadvantages for infant health, we find hypergamy to be associated with higher risks of excessive birth weight and atypical growth compared to homogamy. However, these heterogamy penalty patterns remain small when compared with the large couple-level gradient. Overall, this study provides new evidence on how parents’ educational pairing and combined resources are associated with neonatal health, highlighting a pathway linking couple-level characteristics to early-life health inequalities. The next step in this study is to determine whether these results reflect causal heterogamy effects or endogenous selection processes using an instrumental variable design that addresses non-random selection into heterogamous unions in Austria.

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 Presented in Session 118. Flash Session Families, Partnerships and Health