The probable explanation for the falling twinning rate in Scotland.
D000293:Adolescent; D000328:Adult; D001723:Birth Rate; D001827:Body Height; D001835:Body Weight; D003276:Contraceptives, Oral / Q000009:adverse effects; D005260:Female; D005298:Fertility; D006801:Humans; D009747:Nutritional Physiological Phenomena; D010298:Parity; D011247:Pregnancy; D011272:Pregnancy, Multiple; D012606:Scotland; D012907:Smoking; D012923:Social Class; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
D003276:Contraceptives, Oral