I still think abortion should be legal. Now, I don't happen to believe that a fetus is a person - for me that hinges mostly on cognitive capacity, rather than DNA or "living" status, or obviously on what the Bible supposedly says. But for the sake of argument, let's grant that the fetus is a "person," a fully fledged human being with the rights and protections of an independent adult.
I still think abortion is perfectly justifiable. That is because it is perfectly justifiable to kill a fully fledged adult human being, under certain circumstances. And those circumstances are always present in a pregnancy. If someone is threatening you with imminent, severe bodily harm, you are allowed to kill them. Even if they are not mentally competent, and even if they aren't trying to kill you. I think in pretty much every U.S. jurisdiction, deadly force would be justifiable to prevent an assailant from forcibly inserting a large object into the victim's vagina.
It is true that this assault is not imminent at the point most abortions occur - it is still months away. However, the situations are analogous, because there is no opportunity to avoid the assault other than by use of deadly force. In an attempted rape, you can kill the attacker if you have no reasonable ability to obtain protection by retreating or contacting law enforcement. Likewise, it is justifiable to kill a fetus because you have no reasonable ability to prevent significant bodily harm in any other way.
So, there we are. I don't see how anyone could accept killing an insane rapist in self defense, while simultaneously arguing that abortion should be illegal. Perhaps some people are truly so pro-life (across the board) that they would object to killing a mad attacker in self defense. But I'm guessing that position is rare.