In women with rheumatoid arthritis (RA), giving birth before RA onset does not significantly affect the risk of developing severe RA, according to study results published in Seminars in Arthritis and Rheumatism. However, the results indicated that additional pregnancies resulting in miscarriage might increase the risk of developing severe RA.

The study included women with newly-diagnosed RA who had given birth before RA onset (n=222). Patients returned for follow-up evaluation a median of 8 years later. The researchers used Mantel-Haenszel methods to conduct stratified analyses. They evaluated 5 RA severity measures based on hand and wrist radiographs, physical exams, and Health Assessment Questionnaires for associations with the number of live births in the patients’ histories.

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After adjusting for RA onset age and time to follow-up, the researchers found little evidence that pre-onset parity was associated with altered risk for progression to severe RA.

When stratifying parous women who only had live births by latency (<15 years/15+ years), the results showed no difference in risk for severe RA compared with nulligravid women.

In women with 0 copies but not women with 1 or 2 copies of the RA-risk associated major histocompatibility complex, class II, DR beta 1 gene shared epitope sequence, live birth deliveries were significantly protective for erosion score (risk ratio [RR], 0.26; 95% CI, 0.09-0.89) and joint count (RR, 0.28; 95% CI, 0.09-0.87).

“Although reproductive history may influence a woman’s risk of developing RA, the relationship of parity with long-term RA prognosis appears to be complex,” the researchers wrote.

Reference

Pan TD, Mueller BA, Dugowson CE, et al. Disease progression in relation to pre-onset parity among women with rheumatoid arthritis [published online June 18, 2019]. Semin Arthritis Rheum. doi:10.1016/j.semarthrit.2019.06.011