More Americans Now Pro-Life

I know that I just posted, but I found this article by Gallup which states that, according to the Gallup poll, a majority of Americans now consider themselves pro-life (51%) than pro-abortion ("pro-choice"/42%) for the first time since Gallup began polling on this issue in 1995. Also, roughly the same amount (23%) think abortion should be illegal in all cases as think it should be legal in all cases (22%). I find this interesting considering that, on the whole, Americans seem to be growing more "liberal" on social issues. I wonder what has caused the shift in the "right" direction on the abortion issue.