The umbilical cord is attached on one end to the placenta and on the other end to the fetus. It's the lifeline that allows the fetus to get essential nutrients from the mother's blood.
According to the American Pregnancy Association, the umbilical cord can grow to about 60 centimeters long, which allows the baby to move around freely within the placenta without being restricted. Once the baby is born, the umbilical cord and the placenta are expelled and are detached by cutting the cord. The remainder of the cord that is attached to the baby will heal and eventually fall off, forming the baby's belly button.