"I don't believe in the right to life. If everyone has a right to life, then God is a big sinner; He takes people's lives." I heard someone say that a few years back. That statement could be taken to attack those who say that abortion is murder; which is what most people will probably think when they read it. There is another way to view that, though.
It could also be taken to say that the argument against murdering children in the womb should not be based on an issue of "rights". Although rights might seem to be a key issue to those outside the Church, Catholics should not make their main defense of the Law of God an issue of one's rights. Yes, rights do come up in various aspects of God's commandments, but to say that a baby should not be killed because it has "rights" misses much of the main point.
If we center our discussion on rights, then we must realize that someone can take away rights. It happens every day, either rightly or wrongly (no pun intended). And, furthermore, not everyone agrees on who has what rights, so that does little to support the argument.
What then should we base the discussion on? I have read a few other "pro-life" defenses and, sadly, many of them miss the simple point of "God said so". It is true that pagans (and even some so-called Christians) will disagree that God said so, but that does not make it false. If God said it and revealed such to the Church, then we are obligated to submit to the Church (even if we do not like it).
This is to say, that the argumentation needs to be re-worked. The emphasis needs to change. If we cannot convince people of the authority of God and His Church, then it does little to convince them to grant someone rights (just look at what immoral things are supported in the name of so-called rights!). I must admit I do not know exactly what those changes in argumentation should look like, but we must keep the discussion on the truth, and not let it get sidetracked. We are dealing with people's eternal salvation.