[OlderWiser]

There's a theory that it's actually for the benefit of the baby. During birth, the baby is squished and squeezed and the bones in the skull literally overlap from time to time while the baby passes through the birth canal. A tiny fetus (who is about to become an infant) isn't going to be able to manufacture enough endorphins in order to deal with the pain, so the mother does, instead, in response to her own pain. The baby, being still attached via the umbilical cord and therefore still receiving the benefit of the mother's bloodstream, gets to share in the pain relief. Perhaps, for a tiny baby, there are enough endorphins to actually relieve a great deal of the pain, who knows?

Mind you, that's just a theory. Nobody can really test it, other than measuring levels of endorphins (which has been done, and women who have a natural birth do have higher levels of endorphins and so do their babies, but what that means is open to speculation).

Personally, I never found childbirth that horrifying (have given birth four times). Painful, yeah, but only for the half-hour or hour of transition. The rest of the time was tolerable, if very deeply uncomfortable. It was nothing I couldn't cope with. Sure, I'd rather have been doing something else, but it's not like the pain is constant. I mean, you get a break between contractions. A severe toothache or a migraine is a lot worse, in my experience.

And yes, I do know that my experience is not the same as every woman's, and I understand about complicating factors and so on and so forth, but most women I've talked to who have had both migraines and given birth naturally pretty much agree that labour is a lot more tolerable than a migraine. Your mileage may vary.