Birth control is an excellent tool to keep in your arsenal for reasons including — but certainly not limited to — keeping you from getting pregnant. And now, a new study suggests there might be another, unexpected use for birth control: preventing serious sports injuries. For the study, published in the current issue of Medicine & Science in Sports & Exercise, researchers looked at insurance claims and prescription information for 23,428 women between the ages of 15 and 39. Using that data, they were able to find that women on hormonal birth control were less likely to have anterior cruciate ligament (ACL) injuries that were serious enough to require surgery. The researchers also found that, among those between the ages of 15 and 19, those who did need surgery were 18% less likely to be on birth control than control participants of the same ages. Before puberty hits, boys and girls have about equal rates of injuries to their ACL, which are common in sports. But after puberty, girls are around two times more likely to have an ACL injury. The current thinking is that, along with other physical differences, estrogen may be playing a role here. It could even weaken the ligament, making it more vulnerable to injuries. And so, as this study suggests, regulating estrogen levels — especially in those wild teen years — can help prevent the injuries from being too serious. While this may not be a reason to go on birth control on its own, it does suggest that avoiding serious ACL injuries may be another nice benefit for those already on the medication.