http://www.blueletterbible.org/Bible.cfm?b=Exd&c=21&t=KJV#22Based on the penalties involved, the Bible does not equate abortion with murder - accidental murder carried the death penalty while accidentally killing the unborn was punished with a fine. (Exodus 21:22)
That being said, I am not pro-abortion. I am against Christians working to pass laws to force non-believers to act in accordance with Christian mores as a substitute for evangelism. The Church needs to be there before a woman gets pregnant with an unwanted child with the Gospel, not working to pass laws to punish her for being a sinner.
Or, put another way, if we work to pass laws to make unbelievers act like Christians, how then will we present an example to the World.