How is it possible for a woman to carry someone else's baby?

Invitro Fertilzation. Invitro fertilization is when egg & sperm get together outside the human body & then the developing egg or embyro is transferred into the woman's uterus. Some women have medicat problems that prevent them having a normal pregnancy. It is possible for a totally unrelated woman to carry a child who came from an egg from another woman. It is complicated: medical, legal, social & emotional thing.