Hi Charlie,
Ive not tried it, but believe that anything that helps calm the mum down during labour should be encouraged.
My mum, in 1972, was offered a trial of a course of hypnotism i dont think its the same though (please tell me if it is). She had a few sessions with a hypnotist and was supposed to callhim when she went into labour to be present at th birth and help her through the pain.
She never did call him, as she didnt realise she was in labour. She had no pain, just a funny feeling down below. The midwife came out twice and told my mum she wasnt in labour as she had no pain. The 3rd time she came out, my mum was almost ready to push, she only felt 2nd stage labour.
Whether can be attributed to the hypnotist I havnt a clue, it may be that she inhertited a condition my nan has where she cant feel contractions either. Who knows.
What i know is that the hope that i would be pain free as they are kept me calmer throughout my labour and i think helped dumb down some of the pain that i may have felt, purely because i wasnt nervous.
I wish you luck, please report back to let us know how it goes.