Not magical but physical/hormonal from the stress that results from it, according to intelligent callers to the Charlie Brennan show.
So if you were on a jury in a rape case and the victim was pregnant as a result of the rape, would you accept the Defense making an argument that her pregnancy was evidence that the sex was actually consensual?
Sorry, I, and most people, will believe the scientific evidence rather than the "intelligent callers" you cite. I never heard anything about this "natural defense" in medical school. Based on studies, this is nonsense. Repeating it will only make people look more ridiculous.