This phrase is currently seen most often on the rear bumpers of anti-abortion
ists, aka pro-life
rs. It's a pretty little sticker, with a rose on it and "Choose life" in blue script. I want to get one and put it next to a sticker that says, "If you're against abortion, don't have one
The point is (or should be) choose life. If we make abortion illegal, then it will happen in two cases: rich people who can bribe a doctor to do it anyway, and poor desperate saps who will have it done in back alleys by unqualified creeps. These women will probably get a nasty infection and possibly holes in their uterus, all because the moralists couldn't trust other people to make good decisions on their own. Do you really want someone to be a mother if she can't make decisions for herself? Then her kids won't be able to make decisions either.
Planned Parenthood has a motto: Make every child a wanted child. So many people try to shut them down because some (NOT ALL!) of their clinics also perform abortions. But their true mission is to help make sure that people only get pregnant in the first place if they actually want the kid. See Why are anti-abortion activists also anti-birth control?