title: Natural selection, selection bias and the prevalence of Down's syndrome.
mesh_terms: D000028:Abortion, Induced; D000328:Adult; D002869:Chromosome Aberrations / Q000453:epidemiology; D025063:Chromosome Disorders; D004314:Down Syndrome / Q000453:epidemiology*; D005260:Female; D005313:Fetal Death / Q000453:epidemiology*; D006801:Humans; D008423:Maternal Age; D011247:Pregnancy; D012641:Selection, Genetic