Intervals between childbirths and between contracting a marriage and giving birth to the first child.
D000328:Adult; D001721:Birth Intervals; D001723:Birth Rate; D002648:Child; D004493:Education; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008393:Marriage; D011247:Pregnancy; D013997:Time Factors