A new study suggests that women who have acupuncture while they receive IVF treatment have less chance of getting pregnant.
Acupuncture is believed to affect the autonomic nervous system, which is involved in the control of muscles and glands, and it has been suggested that the therapy can make the lining of the uterus more receptive to receiving an embryo.
And research published last year found that acupuncture could double a woman's chance of getting pregnant when combined with IVF.
But the latest study suggests that women given acupuncture in conjunction with their IVF treatment are 37% less likely to get pregnant than those who are not treated.
Experts from the University of Oklahoma Health Sciences Centre in the US split a group of patients into two groups.
The first group was given acupuncture for 25 minutes before and after embryo transfer, while the other group received no such treatment and acted as controls.
The results showed that more of the women acting as controls (69.6%) became pregnant following IVF than those given acupuncture (43.8%).
Dr LaTasha Craig, a fertility expert at the University of Oklahoma, said out of 43 women in the control group, 28 had babies, while only 18 members of the 46 who had received acupuncture went on to have children.
But Mark Bovey, from the British Acupuncture Council, said: "Up to now all the published research has indicated an increase in pregnancy rates and take-home baby rates.
"Some practitioners treat hundreds of women having IVF each year and largely have good results with it."