When a baby is growing inside its mother, it can’t breathe to eat food on its own. Instead, it gets the oxygen and the nutrition from the mother through a tube. This tube connected to the baby’s belly and is known as the umbilical cord. After the baby is born, it can breathe and feed on its own. So, the doctor cuts the umbilical cord and a tiny stump is left. This stump falls off a few weeks and the baby is left with a belly button.