I think it's hilarious that the anti-abortion camp uses the "pro-choice" label for their opponents. What's that make them, "anti-choice"?
Labeling is so important to controlling values arguments. That's why the gun manufacturers are "pro-Second Amendment" not pro-gun, why smokers are "pro-choice" not pro-smoking, why fracking fans are "pro-energy" not pro-earthquake-and-flammable-drinking-water.
The opponents of choice can call themselves anti-abortion without any negative connotations, but they cannot call their opponents "pro-abortion" because that would be grossly misleading.
If they really wanted to control the discussion they should reframe the argument, into two camps: life-begins-at-conception and life-begins-at-birth. Pro-choicers would have a hard time arguing that abortion does not take a life. They'd have to get into the weeds about the viability of a six-week fetus and that's not a strong emotional argument.