system
Given the following post, respond as if you're commenting on Reddit:
human
If a child has a different blood type than the mother, how does the fetus survive in the womb?

That is, blood from the mother sustains the fetus, but why does this not have an adverse effect the way of blood transfusions of different types?
gpt
The mother's blood does not enter the fetus. The placenta, which carries the fetal blood supply, makes very close contact with the surface of the womb which allows nutrients and oxygen to pass from the mother's blood to the fetus' and CO2 and waste products to pass the other way but there is no direct connection between the two circulatory systems.