(HealthDay News) – For women with rheumatoid arthritis (RA), exposure to methotrexate is associated with a reduced risk of induced abortions, according to a study published online April 16 in Arthritis Care & Research.

Évelyne Vinet, MD, from Montreal General Hospital, and colleagues performed a nested case-control study to examine the rate of induced abortions in women with RA exposed to methotrexate compared with unexposed women with RA. One hundred twelve cases of induced abortions were identified among women with RA, and these cases were matched for age, calendar time, and cohort entry, with 5,855 women with RA.

The researchers found that 10.7% of cases and 21.7% of controls were exposed to methotrexate. Exposure to methotrexate correlated with a significantly lower rate of induced abortions (rate ratio, 0.47). In multivariate analysis, women exposed to anti-tumor necrosis factor (TNF) agents had a trend for an increased rate of induced abortions (rate ratio, 2.07; 95% confidence interval, 0.81–5.27).

“In summary, women with RA exposed to methotrexate appeared to have a lower (not higher) rate of induced abortions than unexposed women. Women with RA exposed to anti-TNF agents may have an increased rate of induced abortions compared to unexposed women,” the authors write. “These results raise concerns on the rate of unplanned pregnancies in women with RA, particularly those on anti-TNF agents, and should prompt future research on counseling, contraception use, and unplanned pregnancies in these women.”

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