Coital rate, sex ratio, and season of birth.
D001723:Birth Rate; D003075:Coitus; D036861:Delivery, Obstetric; D004739:England; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008393:Marriage; D011247:Pregnancy; D012621:Seasons; D012744:Sex Ratio; D014481:United States; D014798:Vital Statistics; D014852:Wales