title: A survey on maternal age and karyotype in Down's syndrome in Japan, 1947-1975.
mesh_terms: D000328:Adult; D004314:Down Syndrome / Q000175:diagnosis* / Q000453:epidemiology; D004787:Environmental Pollution; D005260:Female; D006801:Humans; D007564:Japan; D007621:Karyotyping; D008423:Maternal Age