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
Murder of pregnant women among women ages 20 to 24 and fifth among women ages 25–34 in 1999. The top cause of death in both age groups is accidents. The Unborn Victims of Violence Act, passed in 2004, defines a fetus as a "child in uterus" and a person as being a legal crime victim "if a fetal injury or death occurs during the commission of a federal violent crime." In the U.S., 38 states have laws with more harsh penalties if the victim is murdered while pregnant. Some of these laws defining the fetus as being a person, "for the purpose of criminal