A growing body of research explores the effects of prenatal insults caused by natural disasters on life-cycle outcomes. This paper joins the literature by exploring the long-run effects of prenatal exposure to earthquakes on adulthood and old-age mortality. Using Social Security Administration death records (1975–2005) linked with the full-count 1940 US census and implementing a difference-in-difference methodology, I show that exposure during the first trimester is associated with 1.8 months lower longevity, conditional on survival up to age 34. This effect is equivalent to 22 percent of the white-nonwhite gap in the outcome. The results implicate the relevance of the in-utero period and specifically the onset of pregnancy for later-life health outcomes.