I've witnessed childbirths too. I've also seen some weird, crazy 'pornos' where the women try to use dildos that are the same diameter of a baby. You can tell just by the expression on their face that they're doing it for the camera. I can't see how childbirth could be orgasmic... I hear that some people have to have an incision made on the perineum to accommodate the size of the baby during delivery. In some countries, this is mandatory for all births. Yow! That's a really sensitive area, especially on guys.
This reminds me of that documentary about the women who have orgasms during birth. I've never watched it myself - just seen previews. Sounds pretty ridiculous to me.