In Israel, there was a study of 89 women undergoing In-Vitro Fertilization. Women who where having IVF were nearly twice as likely to become pregnant if they were hypnotized during embyo transfers as women whose transfers were trance free (53% versus 30%).
Hypnosis enhances relaxation during stressful procedures such as IVF. Stress hormones that increase uterine contractions and prevent the embryo from implanting are thought to be a reason by the researchers.
I know that when I have worked with IVF patients in the past, hypnosis indeed helped to relieve stress. Hypnosis also helped to relieve the fears of becoming a parent which might have been contributing to the overall feelings of stress and anxiety. One of the other ways in which I have used hypnosis for successful implantation ( a beautiful baby boy was concieved and born) was to actually have the client visualize the embryo sticking to the wall of the uterus.