When baby is born, he only has 2/3 of his blood is in his body. The remaining 1/3 remains in his umbilical cord and placenta. This blood does not flow into baby until the last stage of labor.
What is the last stage of labor? It is that period of time after baby is born until the time the placenta is born. It’s this stage of labor that the cord actively pumps the remaining blood into baby; blood that is very rich in iron, oxygen, and stem cells.