In an article in the Times Online, Midwife Katrina Caslake reports on her experience achieving orgasm during childbirth. She says that the keys to achieving pain-free, even orgasmic births is for the woman to relax and allow herself to feel sexy. She has science to back up her claims, too: The same hormones that are involved in love and sex are also involved in childbirth.
The practise of midwifery lost popularity in the 18th and 19th centuries, when male doctors were too embarrassed to allow women to feel sexy during childbirth. Since the middle of the last century, midwifery has grown in popularity.