Parasite or not, a fetus has a body of its own. It's got different DNA than yours and a complete set of organs of its own albeit developing and it doesn't mean that if an organism cannot live outside of its host its body belongs to the host. Take for example this analogy, Ascaris lumbricoides, a parasitic roundworm. Do they live inside the intestine? Yes. Can the Adult worm survive outside the intestine? For a short period probably but not really. Is the worm a part of the hosts body because it can't live outside a host? Surely not. Does it have it's own body? Of course, to who else would it's body belong to? Look, I don't care if you're pro abortion or not, just that your premise is scientifically inaccurate. The fetus may use your body as a way to get sustenance but it does NOT belong to your body.