What Is the Function of the Umbilical Cord?

The umbilical cord connects the baby to the placenta in the mother's womb, transporting oxygen and nutrients to the baby, and carrying away waste products, such as carbon dioxide. Still attached to the baby's abdomen at birth, the average umbilical cord is 1/2- to 3/4-inch in diameter, and approximately 20 inches long.

The umbilical cord connects the mother's body to the developing fetus, and has three primary functions: supplying oxygen, delivering nutrients and taking away depleted nutrients and carbon dioxide. Two arteries and one vein in the umbilical cord transport blood through the placenta, which is where the exchange of vital substances between mother and baby occurs. After birth, the umbilical cord is cut and becomes the "belly button" in the child's abdomen.