Bump. I heard this today.
There are some who would follow up with the question, "Well, granted that the baby is not part of my body, still my womb definitely is: so why can;t I ejecte an embryo or fetus from my womb, just as I would eject an invader from my property?"
And the answer is, the baby didn't "invade" you. You in effect invited the baby to come, by allowing somebody to deposit 100 million live sperm into your genital tract. (News Flash: Now known to be the leading cause of pregnancy.) Even if you tried contracpetion, you knew, or should hve known, the risk, and so there's strict liability here.
Getting an abortion would be the equivalent of inviting a child onto your property-- in fact, bringing him onto your property (since he does not even have the power of independent locomotion) --- and then saying he was a trespasser and shooting him.