There was a cool article in the BBC News about a man who hypnotized himself for an operation on his hand. This man had been practicing hypnosis for many years, so was able to do this himself for this operation. I have heard of others who have used hypnosis for different medical procedures using hypnosis, but typically with hypnotherapists there to guide them.
The great thing about birth is it is a natural thing that your body does, so it is an ideal situation to use hypnosis. With Hypnobabies, moms learn to get themselves into deep self hypnosis in 3 seconds using the finger drop technique.
If hypnosis can work for operations, then of course it can work for birth!