The hidden costs of terrorism: The effects on health at birth.

We study the effects of in utero exposure to terrorism in Spain on birth outcomes, focusing on terrorism perpetrated by ETA during the period 1980-2003. We find that in utero exposure to terrorism early in pregnancy, as measured by the number of bomb casualties in the mother's province of residence in the first trimester of pregnancy, has detrimental effects on birth outcomes: in terms of average birth weight (lower), prevalence of low birth weight (higher) and fraction of "normal" babies (lower). While our findings are robust to a host of potential threats to validity, they seem to be driven by exposure to a relatively large number of bomb casualties. Focusing on the deadliest ETA terrorist attack, the Hipercor bombing of 1987 in Barcelona, we find substantial effects on birth outcomes. We then attempt to assess the mechanisms at stake by presenting evidence suggesting that exposure to bomb casualties decreases self-reported health and increases smoking among women, but not among men. While exposure to terrorism during conception does not affect total fertility, there seems to be a compositional change: during bombing periods, those women who conceive are more likely to be married, and married women tend to have better birth outcomes, on average. In addition, we find that exposure to bomb casualties increases fetal deaths. Thus, we interpret our estimated negative effects on health at birth as providing lower bounds to the true effects of in utero exposure to terrorism.