system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When humans/animals are born they go from not breathing to breathing with their first gasp of air. Why is this a one way process and why can't we go back to non breathing as in a womb/egg?
gpt
You wouldn’t need to breathe either if a steady supply of oxygen was pumped into your blood.  Your lungs function is to transfer oxygen into your blood and carbon dioxide out of your blood.  That is exactly what the umbilical cord does for babies.  Blood pumps through this and gets oxygen to all the necessary areas.  So the baby is really just using mom’s lungs until birth.