Induced Abortions in Women With Rheumatoid Arthritis Receiving Methotrexate

Objective To determine the rate of induced abortions in women with rheumatoid arthritis (RA) exposed to methotrexate (MTX) compared with women with RA unexposed to this medication. Methods We performed a nested case–control study using administrative databases from Quebec. All women with RA ages 15–45 years were identified and cases were defined as women having an induced abortion. Each case was matched to ≥1 controls for age, calendar time, and cohort entry. Exposure was defined as having filled ≥1 prescriptions of MTX ≤16 weeks prior to the index date. Results We identified 112 cases of induced abortions in women with RA and 5,855 RA controls. Exposure to MTX occurred in 10.7% of cases and 21.7% of controls. Women exposed to MTX had a lower rate of induced abortions compared with unexposed women (rate ratio [RR] 0.47 [95% confidence interval (95% CI) 0.25–0.89]). In the multivariate analysis, there was a trend toward an increased rate of induced abortions among women exposed to anti–tumor necrosis factor (anti-TNF) agents (RR 2.07 [95% CI 0.81–5.27]). Conclusion Women with RA exposed to MTX have a lower 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.