Q. I can’t carry a pregnancy, so we’re thinking about using a gestational carrier with our own embryos. But why doesn’t a carrier’s body reject the embryo as a foreign body, since it isn’t genetically related to her?
A. Actually, no pregnancy is totally genetically related, because the embryo/fetus has genetic components from both the mother’s egg and the father’s sperm. Therefore, every pregnancy is like a “foreign body.” But a woman’s body has the ability to protect the embryo from her own immune defense system, whether the pregnancy is from her own egg or somebody’s else’s—a gestational carrier’s/surrogate’s or egg donor’s.