In the case of a woman who was raped and wants an abortion, then no. In the case of the couple who has to selectively abort a fetus so that another can live, I would say no.
I disagree, killing one person so another can live does not justify the act of murder. If we all adopted the mentality that we can kill a life to save a life, we'd eventually start removing undesirables from the gene pool to better the superiors. Sound familiar? *cough* Hitler *cough* It doesn't matter if the doctors say they both are going to die unless you take action. Let God decide who lives. Abortion is killing regardless of the circumstances or if the mother was raped or not. Contradicting that is like saying if I shoot a celebrity walking down the street that's murder, but if I kill a nobody who wants to jump off a bridge, it's not. No, it doesn't work like that. We don't have the right to choose if a person lives or dies. I wouldn't give the right to kill me to a soul.