The umbilical artery is a blood vessel that carries deoxygenated blood from the fetus to the placenta during pregnancy. It plays a crucial role in fetal development by facilitating the exchange of nutrients and waste products between the mother and the fetus. Typically, there are two umbilical arteries in the umbilical cord. After birth, the umbilical arteries usually close off and become fibrous cords known as the medial umbilical ligaments. This closure is part of the normal transition from fetal to independent life, as the newborn begins to breathe air and rely on its own circulatory system.