How do babies know to breath after they are born?

Question

How do babies know to breath after they are born?

Answer 1

Once the mouth and airway is clear, a baby's first breath is a cry. (Most of the time. ) The brains medulla oblongotta -forgive the spelling- is what controls breathing in the human body.  So a signal is sent from the brain to the lungs and diaphragm to do their jobs.  The baby does not "know" how to breathe.

Answer 2

It is their instinct to breathe when they are exposed to air and/or they are not getting oxygen from the mother through the umbilical cord.  That's why some parents ask for delayed cord cutting, it helps to ease the baby's transition from inside the womb to the dry world outside.  That's also why it's safe to give birth in the water. :)