The goal of this dissertation is to provide new insights into how the social, physical and health environment during gestation affect the early and later life outcomes of the in utero child. This work is grounded in a biologically-informed model of in utero development and applies state-of the-art econometric methods to populationrepresentative data in order to rigorously examine the impact of a mothers mental and physical wellbeing during the fetal period on both the early-life health and long-term economic outcomes of the in utero child. After a brief introduction, the second chapter reexamines the pioneering work by Douglas Almond (2006), which is thought to establish that in utero exposure to an adverse disease environment has a large, negative impact on health and socioeconomic prosperity that reaches well into adulthood. The analysis in this section casts doubt on the identification strategy used in that seminal work, and suggests that conclusions about the deleterious impact of in utero exposure to the influenza pandemic on socioeconomic prosperity in adulthood are, at best, premature. The third and fourth chapters delve into the topic of the impact of a mother’s mental health during pregnancy on the birth outcomes of the in utero child. Utilizing two traumatic and unanticipated events, the terrorist attacks of September 11th, 2001 and the surge in Mexican Drug War violence, these chapters provide strong evidence that exposure to increased maternal anxiety has a significant negative impact on the early-life health of the in utero child.