Football may get all the attention, but it’s not the only dangerous sport on the field. Researchers say female high school athletes, especially soccer players, are more likely than boys in any sport to be diagnosed with concussions. They presented their research at the 2017 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS).

As neuroscientists learn more about the long-term effects of traumatic brain injury (TBI) on professional athletes, the public has grown more concerned about the safety of youth sports. A blow to the head is not good for anyone, but it can be especially dangerous for kids’ and teens’ developing skulls and brains, causing more severe symptoms and a more difficult recovery.

Experts estimate that 300,000 teenage athletes experience concussions every year. To better understand that number, researchers pulled data from the High School Reporting Injury Online (RIO) survey for the years from 2005 to 2015. The RIO survey includes injury reports for nine sports: boys’ football, soccer, basketball, wrestling, and baseball; and girls’ soccer, basketball, volleyball, and softball.

In that time, athletic trainers using the RIO system documented 40,843 injuries, of which 6399 were concussions. A breakdown of those incidents revealed something surprising: Girls were significantly more likely than boys to be diagnosed with concussions, even when playing the same sport. From 2010 to 2015, the concussion rate in girls’ soccer was higher than that for boys’ football. In the last year of data collection, female soccer players had the highest concussion rate of all athletes.

Lead author Wellington Hsu, an orthopedics expert at Northwestern University’s Feinberg School of Medicine, said that not only were girls’ concussion rates higher than boys’ but that they were also rising faster.

There are a number of reasons this could be happening. The first is that fears about football-related TBI have prompted changes in the way the sport is played on high school fields. The second is that girls may just be getting diagnosed more than boys. “Girls may be more likely to report symptoms from concussion than boys for potential social reasons,” Hsu tells mental_floss.

Male and female bodies are also developing differently in particular places, at varying rates. Hsu says girls’ neck muscles may not be as supportive as boys of the same age, putting them at higher risk for injury.

More research is needed to understand these numbers and their causes, but Hsu said in a statement that his team’s work is a good start. “The new knowledge presented in this study can lead to policy and prevention measures to potentially halt these trends.”