How should we answer the statement that being pro-choice does not mean being pro-abortion?
First, ask, “What is the choice you’re defending to be protected by law?” Explain that it can’t be the choice to bear a child, which was protected by U.S. law long before U.S. law made abortion legal.
So they can’t reasonably argue that they’re defending the right of a couple, or even that of an unwed mother, to have a child. Again, that was already enshrined in U.S. law and thus is not a genuine issue in the abortion debate.
(However, as an important aside, Margaret Sanger, the founder of Planned Parenthood, one of the largest abortion providers worldwide, actually advocated “to protect society against the propagation and increase of the unfit” by means of her “Baby Code.”)
Second, point out that the choice "pro-choicers" are defending is the choice for a couple—or a woman alone—to abort a child. Acknowledge that pro-choicers do not favor the mandating of abortion in many or most cases, as has been the case in China for many years, despite a recent and minor relaxation in its one-baby-per-couple quota. Still, despite their presumably opposing such a government-enforced mandate, the choice pro-choicers are defending is the legal right for anyone who desires an abortion to have that procedure performed on their unborn child. Consequently, to that extent, they're undeniably “pro-abortion,” because they are defending legalized abortion in those cases as a morally good thing that should be available for couples and individuals who seek them.
For more on this subject, please see Trent Horn’s account of his debate with a pro-abortion philosopher.