Vegas, see it that way. There is an embryo, which might have the cognitive abilities of an ape or something around that point and then we have the mother. Usually, the mother will bring the unborn into the world, and if she can't take care of it, she can rely on giving it free for adoption.
In the cases, where we have abortion, there are special circumstances (normally), which put the mother in an enviroment, she cannot handle. Doctors will advise her on the situation, but she is dead set on abortion. You could call it evil, because you will destroy a life-in-potentia or you kill a being on level with an animal. Since there are no animal rights, that'd be not a really violation of anything.
Still, there is a potential life at hand, as you ascertain. But we are speaking of special circumstances and most likely the life of the women is threatened in one way or the other. Either by direct means that'd kill her or by means out of the social environment.
So, should the girl rather live unhappy, perhaps losing her life as it is, through the force of somebody else (those alleged thinkers of good), or should she take priority to her own life.
We can't judge whether the life is more precious than her life, because she hasn't done anything evil by being pregnant, so it is her choice alone to decide and I take it that they don't do a quick run on this.
So, the discussion is not on the level of intelligence and cognitive abilities of the unborn, because we can't truly determine it fully or the right of a life-in-potentia, because this would neglect and violate the rights of a life already in its full bloom.
Instead, we should rely on the reason and wisdom of a well-advised girl (via doctors amongst others) to find the right solution to the problem.
Thus it is a discussion of whether we give the woman the right to her life or not. I know that sounds hard, but I tend to trust women in this.