Umbilical cord from and contains remnants of the yolk sac and allantois. It forms by the fifth week of development, replacing the yolk sac as the source of nutrients for the embryo. The cord is not directly connected to the mother's circulatory system, but instead joins the placenta, which transfers materials to and from the maternal blood without allowing direct mixing. The length of the umbilical cord is approximately equal to the crown-rump length of the fetus throughout pregnancy. The umbilical cord in a full term neonate is usually about 50 centimeters (20 in) long and about 2 centimeters (0.75 in) in
Umbilical cord prolapse Umbilical cord prolapse Umbilical cord prolapse is when, during labor, the umbilical cord comes out of the uterus with or before the presenting part of the baby. The concern with cord prolapse is that pressure on the cord from the baby will compromising blood flow to the baby. The greatest risk factor is having had more than two previous children with the current baby in an abnormally positioned within the uterus. Other risks include a premature or small baby, twin pregnancy, and too much amniotic fluid. Whether medical rupture of the amniotic sac is a risk is controversial. The diagnosis