ELi5: When a baby is born, how are their lungs instantly able to breathe air if they haven’t been breathing air for 9 months?

Question

ELi5: When a baby is born, how are their lungs instantly able to breathe air if they haven’t been breathing air for 9 months?

In: Biology

Answer 1

The negative pressure inside the lungs just pulls the air from outside. After that, there are CO2 receptors at the brainstem that regulates breathing frequencies. Its not active before because the blood from the mother is already regulated, and the pressure inside the lungs are stabilized with the amniotic fluid.

Sometimes the baby can’t breathe because the upper airway is obstructed, mantaining the pressure. Thats why the peds take the baby from the mother first and aspirate any obstruction.