I'm redating this post, which I did over a year ago.
One of the difficulties pro-life advocates have with the pro-choice position is the idea that once the right to life is denied inside the womb, there is no nonarbitrary reason for not denying it outside of the womb. Birth, after all, is going from inside to outside, and a law that makes being born the criteria for a right to life is like passing a law that there are certain buildings in which a person may freely be killed, but outside those buildings it's murder.
Peter Singer is one of those who has pushed the pro-choice argument outside the womb. He defends infanticide in cases where babies are disabled.
Of course, Christianity did not face the abortion issue in its early years, since only modern medicine has made abortion safe. However, early Christians (and early Muslims like Muhammad) opposed the exposure of children after they were born. Typically, of course, it was the female babies that got exposed in the ancient Roman world. So much for gender equality back then.
Is there a good way to defend abortion but not infanticide? Or is it only our sentimental attachment to born babies that keeps "choice" from extending outside the womb?