["Population and Development Review, Volume 47, Issue 4, Page 1025-1047, December 2021. ", "\nAbstract\nThis paper investigates the extent to which in utero exposure to temperature shocks affects birth weight outcomes in Vietnam. Exploiting the variations across districts and conception timing within districts, we show that a one standard deviation increase in temperature relative to the local norm (approximately 0.52°C) during the first trimester of pregnancy reduces the child's weight at birth by 67 g or 2.2 percent. Our heterogeneity analysis suggests that infants living in rural areas, born to poor and low‐educated mothers are especially vulnerable to temperature shocks.\n"]