I frequently hear advocates of choice and abortion basing their opinions on the foundation that "a woman has the right to chooose what happens to her body".
To a certain extent that is fair enough. Subjecting patients to unwanted medical procedures is classed as assualt and battery, although interestingly refusal of treatment is said to require a higher level of competence than consent.
However, when it comes to abortion we immediately hit a massive stumbling block, nay, a wall: the unborn child is not part of your body. Yes, it needs your body, it relies on your body, but it is not part of your body.
Here are some medical facts in support of this statement.
1. The baby has its own DNA, from both its parents. Genetically distinct, he or she is a human being in his or her own right. The baby is not a limb or an organ.
2. The body has an immune system which attacks anything which is not its own. That is why organ recipients have to take immunosupressants. Aha! That proves the baby is part of my body! No, it doesn't. There are two privileged sites in the body. One is found in the eye and the other is the uterus. That is why if you have the lens of your eye replaced with a plastic one ("getting your cataracts done") or you are pregnant you don't have to take immunosuppressants.
3. Haemolytic disease of the newborn. This occurs when there is incompatibility between the blood group of the mother and that of the baby, which leads to the mother's body producing antibodies against the child's blood cells. This condition can cause haemorrhage of the mother and child and (I think) shows that the mother's body recognises that the baby is "foreign".
4. The baby is not a parasite feeding off your body. Parasitism is a non-mutual relationship between organisms of different species where one organism benefits at the expense of the other. The mother and child are clearly the same species.