The problem is, of course, that those polls are questionable due to the very thing Jamesrage just pointed out.
"Pro-Life" means a lot of things to a lot of different people.
If given a poll with only the choices of "Pro-Life" or "Pro-Choice", I'd go pro-choice.
If give a poll with only choices of "Pro-Life" or "Pro-Choice", I imagine most people who believe it should be illegal except for cases of rape, incest, or health of hte mother would hcoose "pro-life"
But according to some, like Jamesrage, that would be a "pro-choice" person. Which begs the question as to what the definition of "pro-life" those polls are using.