Dear Mohan, from all studies by the team of Professor Stuart Hooper and Professor Arjan te Pas, we know that aeration of the lungs is the master switch to transistion a baby from placental circulation to autonomous circulation. As long as the placenta is not delivered, there is gas exchange and the newborn receives oxygen-rich blood via the placenta. It is therefore important that the baby aerates its lungs before cutting off placental circulation - to ensure that baby's heart receives sufficient oxygen rich blood from the placenta during transition. When the placenta has been delivered, there will no longer be any gas exchange, but there still may be a possibility for placental transfusion, which has some benefit to increase blood volume. This is a nice article on this topic: https://www.frontiersin.org/articles/10.3389/fped.2019.00405/full