Like a discussion on a previous thread, why is being pro-life exclusive to Christianity? I would think even an athiest could grasp the concept that a fetus is a baby, since it has its own DNA, its own brain, it's own body...and that ending a pregnancy with abortion is murdering that baby.
One of the best articles against abortion I have ever read was written by a left leaning atheist for those and other reasons.
It isn't really a Christian issue, it is a human issue.