From what I remember discussion of abortion in the Bible is pretty vague and ambiguous. What's more interesting is that there was a strong and almost universal moral prohibition against abortion early in the Christian tradition, from at least the Didache (so likely 1st century).
This is a good, concise summary. One of the biggest falsehoods that gets passed around about Christianity today is that Christian opposition to abortion did not exist until the 1970s. The thing is that this talking point is targeted at Evangelicals, who as a rule do not put significant emphasis on extrabiblical writings. American thought tends to take the Evangelical tradition as the "normal" form of Christianity, to the point that they really don't know how to talk to people who come from churches that put weight on historical as well as scriptural evidence.
Very true, though admittedly St. Augustine, St. John Chrysostom, and Aquinas (among other early Christians) came to their conclusions about abortion more through their understanding of human philosophy and not from a reasoning from the scriptures. Yet, the churches that are the most anti-abortion generally are the ones that claim that their only authority are the scriptures (which are vague at best regarding the beginning of life, and totally silent about the actual practice of abortion), and want nothing to do with church history predating Luther.
