How can a pregnancy surrogate carry a zygote/fetus when surrogate and baby are not biologically related?

Question

Specifically wondering why surrogate’s body doesn’t attack the zygote/fetus as if it’s a foreign body.

Of course as I’ve typed this out I’m wondering if it’s the same reason babies aren’t attacked in the womb in any other situation, the placenta?

In: 3

Answer 1

Same question goes for any pregnancy, actually. Not counting mitochondrial DNA, 50% of your genetic material comes from your father, which is foreign to your mother’s body. What’s to stop a pregnant woman’s immune system from attacking her gestating fetus? We don’t really know all the details. The hand-wavy incomplete answer is that the mothers immune system is suppressed by hormones from the placenta. Exceptions exist.