title: Twins and perinatal mortality: a comparison between single and twin births in Minnesota and in Norway, 1967--1973.
mesh_terms: D001722:Birth Order; D001724:Birth Weight; D001827:Body Height; D005260:Female; D005313:Fetal Death / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D008297:Male; D008910:Minnesota; D009664:Norway; D011247:Pregnancy; D011272:Pregnancy, Multiple; D012737:Sex Factors; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic