A long-term study suggests young women are more likely than their male peers to have a stroke. Researchers analyzed a claims database of insured people in the United States from 2001 to 2014, tallying the number of ischemic (clot-caused) strokes based on hospital admissions.

The data showed no difference in the number of strokes between men and women ages 15 to 24 and in those 75 and older. And more men had strokes among 45- to 74-year-olds.

However, women between the ages of 25 and 44 had more strokes than men in the same age group.

What accounts for the higher incidence of stroke in young women?

According to the lead author of the study, pregnancy, birth control pills, and conditions such as migraines and autoimmune disorders, which are more prevalent in women, may help to explain the findings.

“Non-cardiovascular risk factors play a much bigger role than we had originally thought,” said Dr. Michelle Leppert, an assistant professor of neurology at the University of Colorado.