Twinning.
D005260:Female; D005313:Fetal Death; D006801:Humans; D007231:Infant, Newborn; D008428:Maternal Mortality; D007752:Obstetric Labor, Premature / Q000517:prevention & control; D006473:Postpartum Hemorrhage / Q000517:prevention & control; D011225:Pre-Eclampsia / Q000517:prevention & control; D011247:Pregnancy; D011272:Pregnancy, Multiple; D014428:Twins, Conjoined