Birth order, maternal age, and mental retardation.
D000293:Adolescent; D000328:Adult; D001722:Birth Order; D002674:Child, Institutionalized; D004314:Down Syndrome / Q000150:complications; D005260:Female; D005315:Fetal Diseases / Q000150:complications; D006801:Humans; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000209:etiology*; D008423:Maternal Age; D008875:Middle Aged; D011247:Pregnancy; D012306:Risk