Are you saying that this then would no longer be a question of figuring out how to best satisfy our moral principles, but a difference in moral principles themselves? Information can be used to change a moral position because you can discover that something does or doesn't satisfy your moral principles. But in theory, information shouldn't change your moral principles -- they are independent of facts and logical justification. If a fetus has innate intrinsic value, then wouldn't that be a moral principle? People might argue in pro-life debates that the fetus has value because it is human, or because it has potential, or reason X, or reason Y, but perhaps none of these reasons are the real reason, because the value of a fetus isn't derivative. In which case, this would explain something to me about the apparent lack of logic when people discuss pro-life arguments. People could be making the mistake that morality has 'reasons' and that moral principles can be justified via argument. When all they really need to say is that the life of a baby is sacred. (By the way the lack of logic I was referring to is that some subset of pro-life proponents, that many of my family members happen to represent, argue sincerely that fetuses should be protected because human life is sacred, but then they support fighting in wars. They will argue that soldiers make a choice, and another people or culture are threatening our way of life, etc, but these seem like after-the-fact excuses. Logically, the bottom line is not that human life must be protected, no matter what. So it doesn't matter that fetuses are 'human'. It would make sense that it only matters that they're human babies.)

Let me turn your question around. If your utility function puts value in the mere existence of people, regardless of how they interact with the larger world, doesn't that mean having babies is as wonderful as killing people is terrible? Is somebody with 12 kids a hero?