Marital coital rates, spouses' ages, family size and social class.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D003075:Coitus; D005260:Female; D006801:Humans; D008297:Male; D008393:Marriage; D008875:Middle Aged; D010298:Parity; D012923:Social Class; D013997:Time Factors