Politically speaking, "pro-life" is the term groups founded to oppose legal abortion settled on to describe themselves. They've got first dibs on the expression. If you want to complain that in practice "pro-life" just means "anti-abortion," go wait in line for the time machine.*
While they're waiting, though, what do we say to the people who insist that opposing plastic water bottles is also a pro-life issue?
My proposal is to use the Catechism to provide a framework for "life issues" that is as good as any and better than most.
Here is the Catechism's framework for discussing the Fifth Commandment, "You shall not kill" (click to enlarge):
I propose, then, that for an organization, social program, political platform, etc., to be legitimately called "pro-life," it is necessary and sufficient that
it advocate a correct position on at least one of the above issues; and
it advocate an incorrect position on none of the above issues
(Individual Catholics, of course, are to hold correct positions on all the issues, and advocate for them as prudence dictates.) * The line for the time machine starts anywhere. Just leave a note saying where you're waiting.