This research examines the toll the current drug war in Mexico is having on the early-life health of the next generation. Specifically, this analysis, through the study of a sudden and violent event and use of rich longitudinal data that allows sibling comparisons, measures the birth outcome impact of exposure to increased local conflict, while examining and controlling for behavioral responses (migration and family planning) to that violent environment. The estimates, across multiple samples and specifications, consistently indicate that exposure, early in gestation, to the average increase in local violent crime between the pre-escalation of violence period and 2009 in Mexico leads to substantial decreases in birth weight (75 grams and a ~40% increased risk of being <2,500 grams) that are exacerbated for mothers of low socioeconomic status (~120-125 grams).