Abstract
YAMAMOTO. M., ITO, T., WATANABE, M. and WATANABE, G. Estimated Prevalence of Chromosome Anomalies in the First Trimester of the Japanese Pregnant Population. Tohoku J. exp. Med., 1981, 135 (1), 109-113 - Using the cytogenetic data we have collected in induced abortions, an estimation of the prevalence rate of chromosome anomalies in the first trimester of the general pregnant population was made. Since the maternal age distribution in induced abortions skewed toward the older age group in comparison with that of the general population in Japan in 1975, the maternal age adjustment was conducted. The projected rate was found to be 5.0 per cent. It is inferred that the present frequency may give the lowest limit value, for only the gross chromosome anomalies diagnosed by the conventional Giemsa staining method were counted in the present study.
