Mortality rate of Japanese twins: infant deaths of twins after birth to one year of age.
D001722:Birth Order; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007231:Infant, Newborn; D007564:Japan; D008297:Male; D008423:Maternal Age; D011247:Pregnancy; D012737:Sex Factors; D014427:Twins