t may not be the most pleasant experience to have it placed, but your IUD may lower your risk of cervical cancer.

Women with IUDs are reportedly one-third less likely to get the cancer than those who don’t use one, according to the study, which was published in Obstetrics & Gynecology. The research looked at data from studies on IUD use and cervical cancer history for more than 12,000 women around the world. Even taking different risk factors into account, researchers came to the same conclusion.

What the study didn’t say, however, is how or ​why IUDs lower a woman’s risk of cervical cancer. And since that’s yet to be determined, researchers can’t say for sure that getting an IUD is actually a method of cancer prevention. “It looks real. It smells real. But to be really convinced, we need to go back and do studies to find a mechanism,” Victoria Cortessis, an epidemiologist at the Keck School of Medicine at the University of Southern California, told Live Science.

Right now, the prediction is that it might have something to do with the body’s immune response when an IUD is inserted, since HPV—the virus that almost always causes cervical cancer—most often occurs when the body’s immune system is weak. An IUD might lower a woman’s risk of cervical cancer by helping prevent an HPV infection, according to Cortessis, but that’s just a hypothesis.

So you can rest assured knowing your IUD is preventing pregnancy—and maybe cancer—at the same time.