system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Where does the blood in a fetus comes from? Is it transferred from the mother or created by its own cells?
gpt
It’s created by its own cells.

No blood from the mother enters the fetus or vice versa, it stays separate.

The fetus’s blood and the moms blood both path close by each other in the placenta to transfer nutrients, but the blood itself isn’t mixing.