Mongolism, delayed fertilization and human sexual behaviour.
D000293:Adolescent; D000328:Adult; D002869:Chromosome Aberrations; D003075:Coitus; D004314:Down Syndrome / Q000453:epidemiology*; D005260:Female; D005306:Fertilization; D006801:Humans; D008297:Male; D008393:Marriage; D008423:Maternal Age; D008875:Middle Aged; D008938:Mitosis; D010063:Ovum / Q000502:physiology; D011247:Pregnancy; D012725:Sexual Behavior; D014314:Trisomy