Surveillance system of chromosome abnormalities in early embryonic stage of induced abortions

Chromosome analysis was made in induced abortions within 12 gestational weeks after the first day of the last menstrual period. There were 22 cases (7.3%) of gross chromosome anomalies in 300 materials. About a half of aberrant embryos were born to mothers who had positive histories of drug treatments or X-irradiation for various reasons.