From the article: ...researchers asked the participants to rank their own Political Orientation on a scale of 1 to 7, where 1 is extremely conservative and 7 is extremely liberal. That means that if the average participant had come out to 4.0, it would indicate a perfect balance on liberal vs conservative sentiment. This group came out to 4.7, which is close to balanced, showing a slight liberal bent, much like the general population.

Your source does not support your claim that "close to half of American women do not support abortion."

46% may reasonably be described as close to half, but the details on the support for legal abortion in the poll (both on the page you linked and the additional information from the poll linked from that page) is inconsistent with the idea that "pro-life" identity equates to not supporting legal abortion, as the proportion of the population opposed to legal abortion is much less than half the proportion identifying as "pro-life".