The effect of ambient temperature shocks during conception and early pregnancy on later life outcomes

A large body of research has recently shown that early life or in utero shocks, especially climatic shocks, may affect long-run human capital outcomes. Most of these effects are assumed to be biological – including poor nutrition during critical windows of fetal development, or through increased maternal stress. However, in addition to these biological effects, climatic conditions at the time of conception may also cause changes in parental behavior, not only affecting the mix of parents who conceive, but also the characteristics of the children once born. This paper explores whether increases in ambient temperature at the time of conception, while in utero, or after birth affect educational and health outcomes as adults. Using Census and Demographic and Health Survey data from sub-Saharan Africa, we show that individuals conceived during high temperatures have higher educational attainment and literacy. In addition, we find evidence of temperature effects at other times in utero, especially during the first trimester. We then explore the biological and behavioral mechanisms through which this effect may occur, including heat-induced changes in sexual behavior, differences in parental characteristics, and intensified fetal selection. We conclude that fetal selection is the most likely mechanism driving our result.