If you make abortion "murder" you are right, but many pro choice (and in my opinion with very solid theological backing) would take the position that an unborn fetus is not alive, at least not until it breathed his first independent breath. Other theologians would argue that a fetus is alive if he "could" live independently outside the womb (about 26/27 weeks or so). Only a minority take the position that (IMHO) is contrary to Genesis, that life starts at conception.