I've said in the past that I don't "like" abortion, but I'm not passionate about the issue. People who are passionate about it make me uncomfortable, and anytime I write about it I know I'm inviting passionate people to descend upon me. Thus I don't mention it often.
I do not believe a zygote has rights-- you can't violate it. I believe a full-term baby does have rights, even though it isn't capable of exercising many of them yet. I believe those things as strongly as I believe gravity is a real force which I can depend on to be consistent, but I can't think of a way to prove it so I can't be 100% positive.
That means I believe somewhere along the path from zygote to blastula to embryo to fetus to baby, this living tissue- the zygote into the future, undergoing continual cell division- becomes a human. Not just human tissue or a unique human genetic thing, but A Human with human rights no one has the right to violate. And I don't know how to know where that happens so my position would be to err on the side of assuming rights earlier rather than later.
I do absolutely believe pregnant women have every human right.
It seems to me that rights could probably be said to correlate to nervous system function in some way. Yes, I know this opens the door to debating how functional a human's brain must be before I would say they have rights. And, like all the rest of this, I don't know.
This lack of knowing is why I can't be passionate about it. It's why I'm not going to go hard against others for their opinion, whichever way they believe. I'm not going to argue very hard for my opinion on the topic. Because, no matter how passionate you are on either side, it is an opinion (not based on enough facts) you are passionate about. You don't know, even if you believe you do. No one does. It depends on subjective definitions and assumptions. It leads to absurd declarations from both sides when passion gets involved.
And, usually, it leads to calls to make something "illegal". I don't believe it's ever right to get government or its "laws" involved in anything.
If you are passionate about the topic, on either side, do what you feel you must. Just don't expect much support or attention from me.