Frequency of Live Births among Survivors of Hiroshima and Nagasaki Atomic Bombings

Abstract

The purpose of this report is to present the results of an analysis of the distribution of live births among atomic bomb survivors in Nagasaki and Hiroshima. It represents a segment of an effort to assess the long-term effects of the radiation on fertility. The importance of research on the fertility of the survivors has been recognized since the earliest investigations in those cities. The Joint Commission for the Investigation of the Atomic Bomb in Japan reported on the period just subsequent to the bomb (1). A diminution in sperm counts correlating with distance from the hypocenter was noted. Histological changes, particularly in the germinal epithelium of the testes, were seen in fatal cases within the first few weeks after the bomb. Abnormal terminations, mostly inviable, were relatively frequent in a sample of pregnancies in Nagasaki observed during the three months after the bomb. Neel and Schull' studied pregnancy terminations in the two cities between 1948 and 1953. Whereas small alterations in the sex ratio were noted, no well-defined relationships were observed in their malformation or stillbirth data. The above studies were not directly concerned with the long-term effect of radiation on fertility. The former was a study of the immediate postbomb months, and the interest of the latter was in genetic effects. Most of the links in the chain of events leading to the production of viable births cannot conveniently be analyzed. Some are unknown to the subject, such as quality and number of gametes. Others are highly personal and not readily reported, such as frequency of intercourse, use of contraceptives, and the practice of abortions. Affecting this chain, moreover, are covariables that may be partially confounded with radiation. These include education, age, and income, for example.