Letter: Oral contraception and sex ratio at birth.
D001724:Birth Weight; D003276:Contraceptives, Oral / Q000494:pharmacology*; D005260:Female; D006801:Humans; D006814:Hungary; D008297:Male; D012744:Sex Ratio; D013223:Statistics as Topic; D006113:United Kingdom; D014481:United States
D003276:Contraceptives, Oral