My ex crusaded a lot about this one issue, because she'd actually read the relevant scientific papers and people in the popular press don't seem to. People in the mainstream press basically just started reporting it was "discovered" or it "turns out" that the Pill prevents implantations, when no such thing was discovered -- pro-life political flacks just suddenly started pointing out that it was *possible* and turned it into a political issue, and the idea that the Pill prevents implantation suddenly became "common knowledge". (Really, most scientists just don't know, and the scientists who have an opinion say it probably doesn't.)