A new study suggests that both men and women in the United States are getting more kidney stones.

Between 1984 and 2012, kidney stones diagnoses increased more than fourfold among women and twofold among men, according to the study published Monday in the Journal Mayo Clinic Proceedings and reported on by CNN .

Kidney stones are common, affecting roughly 10% of the population at some point in their lives. They’re formed when a person’s urine contains more crystal-forming substances like uric acid, calcium, and oxalate, than fluid, according to the Mayo Clinic,.

The reason women’s numbers seemed to grow much more than men’s is due to the fact they started from a relatively low base. The largest increase came for young women from 18 to 39. In 1984, 62 women in every 100,000 would have kidney stones annually. By 2012, that number had jumped to 252.

Another reason for the increase could simply be improved methods to diagnose kidney stones, which are usually found through CT scans. In 1995, there were just 2.7 million CT scans performed in the U.S. compared to 80 million in 2016.

Kidney stones can often be prevented by drinking plenty of water.