eli5: Why does blood type not matter when choosing a surrogate mother?

Question

Organ transplants require that the donor have a blood type that is compatible with the recipient.

Why is that not a requirement when you are actually growing the organs themselves during a surrogate pregnancy?

Thanks in advance!

In: Biology

Answer 1

The same reason they don’t matter when people have babies without the surrogate, parents’ blood doesn’t mix, and nor does the blood of the foetus with the mother’s. Placenta exchanges nutrients, oxygen/CO2 and waste products with the mother’s circulatory system, but blood cells never cross that barrier.