In placental mammals, the umbilical cord is a tube that connects a developing embryo or fetus to its placenta.
It contains one or two major vessels, buried within Wharton's jelly, for the exchange of nutrient- and oxygen-rich blood between the embryo and placenta.The umbilical cord develops from, and contains, remnants of the yolk sac and allantois.
In humans, the umbilical cord in a full term fetus is usually about 50 cm long and about 2 cm in diameter.
In the third stage of labour, the uterus expels the placenta along with the cord from the mother's body.
After the cord is separated from the placenta, the umbilical stub on the newborn's belly dries and comes off after a few days.
It leaves only a small scar (the umbilicus) behind.
In humans, the cord is clamped or cut after birth.