Birth order of twins, Apgar score, and perinatal mortality. Second twin has higher mortality and lower Apgar score (numerical rating of condition) than first twin.
D001722:Birth Order; D005260:Female; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D008297:Male; D010808:Physical Examination; D011247:Pregnancy; D013223:Statistics as Topic; D014427:Twins