Too hot to hold: the effects of high temperatures during pregnancy on endowment and adult welfare outcomes

We examine the relationships between high temperatures during pregnancy and birth weight and later outcomes using random temperature fluctuations across 131 counties in China. One standard deviation increase of high-temperature days during pregnancy triggers about 0.07 kg lower birth weight, and, in adulthood, a 0.80 cm decrease in height, 0.27 fewer years of schooling, 13.30% less annual earnings, and 8.77%, 10.96%, and 7.31% of one standard deviation lower for evaluated health, word-, and math-test score, respectively. The impacts seem to be concentrated in the second trimester. Such effects should be included in calculations of the costs of global warming. Back-of-the-envelope predictions suggest that at the end of the 21st century, newborns on average will weigh 0.02-0.09 kg less; losses in height and education years will be 0.27-1.05 cm and 0.09-0.35 years, respectively. We also conclude that adverse effects of high temperatures are more likely to be consistent with physiological effects than income effects, because: (i) places with the high proportion of heat-tolerant crop area do not mitigate any estimated temperature sensitivity during pregnancy and (ii) total precipitation and high temperatures in the last year growing season before birth have no significant effects on all outcomes.