The use of birth control pills, but not estrogen therapy, lowers the risk of developing rheumatoid arthritis, according to a new report. The findings suggest a dose-related effect, as estrogen drugs are typically one-sixth as potent as birth control pills.

Although previous reports suggest a role for sex hormones in the development and progression of rheumatoid arthritis (RA), the authors explain in the February issue of The Journal of Rheumatology, studies investigating the influence of estrogen drugs on the development of RA have yielded conflicting results.

Scientists investigated whether exposure to either birth control pills or estrogen therapy influenced the devel-

opment of rheumatoid arthritis in women. The researchers used data from The Rochester Epidemiology Project.

Women who ever used birth control pills had a 43 percent lower risk of having RA, the authors report, though there was no association between the current use of such pills and RA.

In contrast, exposure to estrogen therapy did not influence the development of RA, the researchers found.

The investigators calculate that the number of women who develop RA could drop by about 38.6 percent if the entire female population of Rochester were exposed to birth control pills.

Source: Journal of Rheumatology, February 2004