The effect of zygosity on the birth weight of twins.
D001724:Birth Weight; D005260:Female; D005306:Fertilization; D005333:Fetus / Q000276:immunology; D005838:Genotype; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D008431:Maternal-Fetal Exchange; D010060:Ovulation; D010063:Ovum; D010298:Parity; D010920:Placenta; D011247:Pregnancy; D012737:Sex Factors; D014427:Twins