Although it's been used in Eastern medicine for thousands of years, scientists are still unsure if acupuncture increases a woman's chance of getting pregnant.
A review of data from 13 recemt studies found that acupuncture did not improve the pregnancy rate among women undergoing in-vitro fertilization.
The review did find that acupuncture led to a slight improvement in the live birth rate. However, that benefit was only found among women who had acupuncture on the day embryos were transferred into the uterus.
Having an acupuncture treatment when eggs were being retrieved or in the days after embryos were implanted did not improve a woman's chance of getting pregnant.
Lead review author Ying Cheong said that two of the studies showed some benefit from acupuncture, "but they are not randomized, which is a method we use to ensure that the study is done fairly."
The review was conducted by researchers with The Cochrane Collaboration, an international organization that compiles and analyzes findings of medical studies.
The findings are published in The Cochrane Library.
The use of acupuncture to boost fertility dates back 8,000 years to Taoist traditional medicine, but has been used in Western medicine for less than 100 years.
An acupuncturist inserts tiny needles into pressure points throughout the body that are believed to be linked to internal organs and systems.
Until this review, acupuncture's effect on fertility treatments was unclear.
"There are several theories as to how acupuncture may work," said Cheong, a senior lecturer and consultant in obstetrics and gynecology at the University of Southampton in England. "Acupuncture has been shown to alter endorphin levels, which in turn can affect (sex hormone) secretion."
Animal studies have also shown that acupuncture can influence the release of stress hormones that actually benefit reproduction and pregnancy.
Acupuncture may also reduce uterine artery resistance, which may make the uterus more receptive to implanted embryos.
The researchers noted that there are some limitations to studying how traditional Chinese medicine may benefit a Western technique. In particular, the studies employed a variety of acupuncture techniques applied to different pressure points at different times during the reproductive process.
The reviewers did confirm one benefit of acupuncture. When they analyzed the studies for adverse effects, they found relaxation to be the most frequently reported reaction.
