Researchers at Yale University School of Medicine say a special form of acupuncture can help reduce the back and pelvic muscle pain many pregnant women suffer from.

The study appearing in The American Journal of Obstetrics and Gynecology found that women who had acupuncture needles held in place on three pressure points on the ear for a week reported significant reductions in muscle pain, compared to those who had acupuncture needles placed in areas not believed to help in pain relief or those who didn’t have any acupuncture, according to Reuters.

In addition, the women who had the ear acupuncture had lasting relief. A week after treatment ended, 68 percent said they still had a 30 percent reduction in pain.

According to the study’s author, the muscle pain experienced during pregnancy can set the stage for chronic pain afterwards.

Researchers involved with the study say the ear acupuncture method is an inexpensive, all-natural way to treat pain during pregnancy with few side effects. They note that more studies are needed to determine if extended continuous ear acupuncture yields a more sustained effect.