Early origins of disadvantage: Maternal stress, birth weight and educational outcomes

A growing body of research highlights that in-utero conditions are consequential for individual outcomes throughout the life cycle, but research assessing causal processes is scarce. This paper examines the effect of one such condition "prenatal maternal stress" on birthweight, an early outcome shown to affect cognitive, educational, and socioeconomic attainment later in life. Exploiting a major earthquake as a source of acute stress and a difference-in-difference methodology, I find that maternal exposure to stress results in a significant decline in birthweight and an increase in the proportion of low birthweight. This effect is focused on the first trimester of gestation, and it is mediated by reduced gestational age rather than by factors affecting the intra-uterine growth of term infants. The findings highlight the relevance of understanding the early emergence of unequal outcomes and of investing in maternal wellbeing since the onset of pregnancy.