Perinatal mortality of twin fetuses and newborns.
D001724:Birth Weight; D004200:Diseases in Twins; D005260:Female; D005313:Fetal Death / Q000453:epidemiology*; D005865:Gestational Age; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000401:mortality; D008297:Male; D011044:Poland; D011247:Pregnancy; D014427:Twins