Twin pregnancy--the effects of recent socioecological factors.
D001789:Blood Group Antigens; D036861:Delivery, Obstetric; D005260:Female; D006801:Humans; D008423:Maternal Age; D010298:Parity; D011159:Population Surveillance; D011247:Pregnancy; D011248:Pregnancy Complications; D011263:Pregnancy Trimester, Third; D011272:Pregnancy, Multiple; D012606:Scotland; D013223:Statistics as Topic; D014427:Twins
D001789:Blood Group Antigens