The baby's respiration and circulation change when the baby is born in the sense that it no longer relies/depends on the mother for oxygen.
While in the womb, the respiration and circulation of a baby is done by the mother. The mother and the baby inside are connected through the placenta. The placenta connects them through the circulatory system of the mother. The waste and carbon dioxide is also delivered through the blood vessels of the placenta which enters the blood stream of the mother to be eliminated.
When the mother receives nutrients and oxygen in her blood stream, it is also distributed to the fetus.
