Multiple pregnancy.
D000022:Abortion, Spontaneous / Q000453:epidemiology; D000748:Anemia, Macrocytic / Q000453:epidemiology; D000773:Anesthesia, Obstetrical; D001724:Birth Weight; D036861:Delivery, Obstetric; D005260:Female; D005313:Fetal Death / Q000453:epidemiology; D006801:Humans; D008131:London; D007752:Obstetric Labor, Premature / Q000453:epidemiology; D006831:Polyhydramnios / Q000453:epidemiology; D006473:Postpartum Hemorrhage / Q000453:epidemiology; D011225:Pre-Eclampsia / Q000453:epidemiology; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000453:epidemiology; D011272:Pregnancy, Multiple; D014427:Twins