Acupuncture appears to cut the chances of successful IVF, research suggests.
Acupuncture is said to release the body's vital energy
It had been thought that acupuncture may impact on the nervous system to help make the lining of the uterus more receptive to receiving an embryo.
Previous research appeared to support this idea, with the pregnancy rate doubled when IVF was combined with the ancient therapy.
But the latest University of Oklahoma study found the twin approach led to a drop in pregnancy rates.
The researchers found women given acupuncture were 37% less likely to get pregnant than those who were not treated.
A total of 97 patients took part in the study. One group was given acupuncture for 25 minutes before and after the embyro was transferred from the test tube to the womb.
The pregnancy rate in the group who did not receive acupuncture was 69.9%, compared with just 43.8% among those who were given the therapy.
Researcher Dr LaTasha Craig, said: "The results of our study suggest women having fertility treatment should not be advised to have acupuncture."
But she added: "This contradicts the findings of previous studies. I think more research needs to be done."
Dr Craig said it was possible that the benefits of acupuncture might be counteracted by the stress of undergoing therapy directly before IVF.
Mark Bovey, from the British Acupuncture Council, said: "This seems to fly in the face of all the published research.
"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."