First of all, I think that abortion in most cases, while not virtuous, is morally acceptable. However, the argument based on the assumption that we should be able to do whatever we want with our bodies, is unsound. An argument for abortion being moral might go like this:
- If someone chooses to do something to their body, then that act is morally permissible.
- Abortion is choosing to do something to one's body.
- Abortion is morally permissible.
Now, this is a valid argument clearly. However, the first premise is questionable. We might ask, well what about public masturbation? Is this okay just because it is someone doing something to their body? Most people would say that if the people in view of the person masturbating disapprove, or are hurt, or scarred by it in some way, that it wouldn't be morally permissible.
However, the proponent of this argument might say,Well, maybe it isn't just because they are doing something to their body that makes it right. Maybe its because it doesn't hurt anyone. Abortion doesn't scar anyone, or mentally traumatize anyone , unlike public masturbation". But to that you might say, what about the relatives who wanted to see a baby? Are they not hurt by the abortion? You might say "Well yes, but the pros outweigh the cons". Many people would actually be inclined to agree, but you know what? This is no longer an argument of "My body, my choice", it is "the positive outcomes outweigh the negative outcomes".
There are some reasons for why abortion is morally permissible, but having some inalienable right to do whatever you want with your body isn't one.