I agree, Prospect. If the article is going to claim there is overwhelming evidence for his statement, then it certainly would be appropriate (expected, really) to list some of that evidence.
The evidence in my mind is logic. If you think about it, it only makes sense that an unborn baby would be able to feel pain. Unborn babies are human at the moment of conception (this is the point where an anti-lifer might disagree with me). Humans feel pain. Therefore, unborn babies feel pain.
I suppose there is the issue of when all the circuitry for pain is developed in a fetus, but really this whole argument (babies feel pain) is irrelevant to me, anyway. Regardless of what the baby feels, you're still killing it, and killing is wrong.