Here's the thing, I get it. The condom breaks, birth control fails, shit happens. But it's still murder. If someone gets drunk, and accidentally kills someone, they don't get let off the hook. If they build something, and they fuck up, and someone dies, that's homicidal negligence, and they aren't let off the hook. In almost every abortion case, it's due to making mistakes at a young age (kids are very dumb), women getting raped, families can’t financially take care of a new child, birth control fails, just like you said. And that's no excuse for homicide. Only real thing is self-defense, and I guess you can argue that if the mother's life is truly in danger.