Social stratification in the womb : the effect of social origin on birth outcomes

This dissertation is a collection of three empirical chapters contributing to the understanding of the relationship between family of origin socio-economic background and birth outcomes. For this investigation, I draw from high quality cohort studies from the United Kingdom and vital statistics from Spain. Overall, I find that there is a strong and persistent relationship between family of origin socio-economic background and birth outcomes. The first study shows that disadvantaged mothers delivered children with poorer birth outcomes respect to their advantaged counterparts for the large share of the last fifty years in the United Kingdom. And maternal unhealthy behaviors such as prenatal smoking play an important role in accounting for socio-economic disparities. In the second study, I report substantial geographical variation in the association between family socio-economic background and birth outcomes in Spain, suggesting that spatial patterns of intergenerational mobility found by previous research may be visible as early as at birth. In the third empirical chapter, I study a natural experiment and show that exposure to exogenous prenatal maternal stress is more detrimental for disadvantaged mothers, and that maternal behaviors or the complex biology behind stress may account for this result. All in all, these results bring novel evidence on the early transmission of status across generations, integrating classic stratification research with insights from epidemiological, economic and health research. Finally, I outline how further research may improve our understanding of the role of birth outcomes in the stratification process.