It sounds far-fetched — sticking needles in women to help them become pregnant — but a scientific review suggests acupuncture might improve the odds of conceiving by in-vitro fertilization if done right before or after embryos are placed in the womb.

The surprising finding is far from proven and there are only theories for why acupuncture might work. However, some U.S. fertility specialists say they are hopeful the relatively inexpensive and simple treatment may ultimately be recognized as a useful addition to traditional methods.

"It is being taken more seriously across our specialty," and more doctors are training in it, said Dr. William Gibbons, who runs a fertility clinic in Baton Rouge, La., and is past president of the Society for Assisted Reproductive Technology.

"I have not seen proof ... but we wouldn't mind at all" if it turned out to work, he said.

The analysis was led by Eric Manheimer, a researcher at the University of Maryland school of medicine, and paid for by a U.S. government agency, the National Center for Complementary and Alternative Medicine. Results were published Friday in the British medical journal BMJ.

Conception rates increased 65 per cent

Acupuncture involves placing very thin needles at specific points on the body to try and control pain and reduce stress. In fertility treatment, it is thought to increase blood flow to the uterus, relax the cervix and inhibit "fight or flight" stress hormones that can make it tougher for an embryo to implant, Manheimer said.

The analysis pools results from seven studies on 1,366 women in the United States, Germany, Australia and Denmark who had in-vitro fertilization, or IVF. The procedure involves mixing sperm and eggs in a lab dish to create embryos that are then placed in the womb.

Women were randomly assigned to receive IVF alone, IVF with acupuncture within a day of embryo implantation, or IVF plus sham acupuncture, in which needles were placed too shallowly or in spots not thought to matter.

Individually, only three of the studies found acupuncture beneficial, three found a trend toward benefit and one found no benefit. When results of these smaller studies were pooled, researchers found the odds of conceiving went up about 65 per cent for women given acupuncture.

Experts warn against focusing on that number, because this type of analysis with pooled results is not proof acupuncture helps at all, let alone by how much.

IVF results in pregnancy about 35 per cent of the time. Adding acupuncture might boost that to around 45 per cent, the researchers said.