Congenital Malformations and Perinatal Deaths among the Children of Atomic Bomb Survivors: A Reappraisal.

From 1948 to 1954, the Atomic Bomb Casualty Commission conducted a study of pregnancy outcomes of children of atomic bomb survivors who had received radiation doses from zero to near-lethal levels. Past reports (1956, 1981, and 1990) on the cohort did not identify significant associations of radiation exposure with untoward pregnancy outcomes such as major congenital malformations, stillbirths, or neonatal deaths, individually or in aggregate. We have re-examined the risk of major congenital malformations and perinatal deaths in the children of the atomic bomb survivors (N=71,603) using fully reconstructed data to minimize the potential for bias, with refined estimates of the gonadal dose from the Dosimetry System 2002 and refined analytical methods for characterizing dose-response relationships. The analyses show that parental exposure is associated with increased risk for major congenital malformations and perinatal deaths, but the estimates are imprecise for direct radiation effects and most are not statistically significant. Nonetheless, the uniformly positive estimates for untoward pregnancy outcomes among children of both maternal and paternal survivors are useful for risk assessment purposes, although extending them to circumstances other than atomic bomb survivors comes with uncertainty as to the generalizability of the Hiroshima and Nagasaki populations.