Abortion, premature delivery, stillborn, and malformations

Since A-bomb disaster in Hiroshima and Nagasaki, genetic effects of A-bomb radiation have been investigated in the offspring of A-bomb survivors. This paper outlines the results of the previous studies in the context of the historical backgrounds. An earlier survey using a cohort of 71,280 children of Hiroshima and Nagasaki A-bomb survivors and a suitable control population of non-exposed 55,870 persons have dealt with the stillborn, neonate death, 9-month-old infant death, malformations at birth and 9 months after birth, and sex ratio in F1 offspring; it was found that there was no significant difference in these items between the exposed and non-exposed groups. The other survey using fetal and neonatal autopsy cases has revealed that the incidence of malformations was significantly higher in children born to A-bomb survivors than those of the control population (18.5% vs 11.0%); however, there was no evidence of genetic abnormalities specific to the group of A-bomb survivors. Until now, no definitive conclusions of the sex ratio at birth have been drawn. Regarding height in F1 offspring, no significant difference existed between the exposed and non-exposed groups. Nor was there significant difference in malformations in F1 and F2 offspring between the group of A-bomb survivors and the suitable control group. (N.K.)