The umbilical cord serves an amazing function as a link between the mother, through the placenta, and the growing fetus. A developing embryo or fetus receives oxygenated, nutrient-rich blood from the placenta through the umbilical cord.
The umbilical cord serves as a conduit to move oxygen and nutrients from the mother to the growing fetus during pregnancy. The umbilical cord also takes away waste materials from the developing baby and allows the mother's body to eliminate the waste.
A healthy umbilical cord has three blood vessels: two umbilical arteries and one umbilical vein. The umbilical cord is usually about 18 to 24 inches long and is nearly an inch in diameter, which is much larger than many people realize. A special coating called Wharton's jelly strengthens the umbilical cord and protects the blood vessels.
The umbilical cord first develops around the fifth week of pregnancy and is created from the leftover yolk sac. It starts out no longer than the length of the baby's head to tail but soon grows larger and longer until it reaches full size.
The maternal end of the umbilical cord attaches to the placenta, a large, blood-filled organ that helps exchange nutrients, oxygen and waste between mother and fetus. On the other end, the umbilical cord attaches to the fetus at the abdomen, through what will be the site of his belly button after birth. The umbilical cord blood vessel splits with a portion of the blood going to the liver and the larger portion of the blood going to the heart.
There are several complications related to the umbilical cord that can occur during pregnancy. Sometimes only one artery develops in the umbilical cord making only two total vessels and in these cases the baby has heart defects in up to 20 percent of cases. Rarely a cord fails to develop at all and the baby is attached directly to the placenta, or the abdominal organs don't close into the body and are herniated out of the body attached to the umbilical cord. Another set of serious complications that can cause stillbirths include cord compression, cord prolapse or a knot tied in the cord that pulls and cuts off the blood supply.
After birth, changes in the baby's body cause the blood vessels of the umbilical cord to clamp down and stop pulsating, which stops the exchange of blood between baby and placenta. This happens naturally within 10 minutes of the infant's first breath and many parents choose to wait until after the cord stops pulsating before clamping and cutting the umbilical cord. After the cord has been cut, any remaining stub on the baby's belly will slowly dry and fall off, leaving the infant with a navel, or belly button. This usually happens within 10 days after birth.