The number of women diagnosed with rheumatoid arthritis has jumped significantly over the past decade, according to experts at the Mayo Clinic.
Ten years ago, 36 out of 100,000 women developed the condition every year.
The new data shows that number had jumped to 54 out of 100,000 women.
The researchers don't know why there's been an increase. The number of men with rheumatoid arthritis has remained steady.