twin types. monozygotic or dizygotic placentation of twins, monochorionic

placenta newborn fetal anatomy growth medicine medical child white development womb vector prenatal biology pregnant pregnancy baby embryo fetus uterus human identical genetics monozygotic health fraternal unborn cord fertility reproduction diamniotic placentation maternity infant elements people month gynecology obstetrics umbilical stage science flat genes twin types dizygotic monochorionic monoamniotic dichorionic