Apollo, either a fetus is not a person, as basically any measure of a person would conclude, or it is a person and entitled to be viewed as such and entitled to the same rights as everyone else. You can't really go halves with that. Or 3/5ths.
Also, first trimester fetuses are not people.
As far as personhood is concerned, note that even granting full legal personhood to foetii would not really restrict abortion when the mothers life or health is in danger. In that case, it is basically killing people in self-defense (or defense of others), and that is allowed no matter what.
I know that. I've just always been uncomfortable with abortion and that probably makes me take a fairly weak stance.
If I think about it rationally, I can conclude that abortion is acceptable as long as the fetus is not viable and hasn't developed enough to feel pain. After that, it has to be limited to cases where the mother's life is at risk.
A lot of my discomfort comes from the fact that I haven't done much research on the subject, so I have little idea when the cut-off point would be (though I imagine a first trimester fetus wouldn't have developed that far).
Here is an overview of possibilities:
http://en.wikipedia.org/wiki/Beginning_of_human_personhood#Biological_markersId go with the reverse of "higher brain death" when brainwaves appear, at 5-6th month.