Disease Progression in Relation to Parity among Women with Rheumatoid Arthritis
Women with rheumatoid arthritis (RA) often experience amelioration during pregnancy followed by a flare-up postpartum, but the relationship of pregnancy and childbirth to RA prognosis is unclear. We examined whether parity prior to RA onset was associated with longer-term disease severity and how elapsed time from birth of the last child to RA onset (latency) influenced this association. A cohort study was conducted on 222 women diagnosed with RA between 1986 and 1991, who returned for follow-up evaluation approximately 8 years later. Stratified analyses using Mantel-Haenszel methods were conducted to evaluate the association between parity and 7 specific RA severity measures based on radiographs, physical exams, and Health Assessment Questionnaires. Overall, after adjusting for age at RA onset and age at follow-up, we found limited evidence of altered risk of severe RA with respect to parity; relative risks (RR) ranged from 0.74 (95% confidence interval [CI] 0.48-1.15) for number of affected joints to 1.67 (95% CI 0.99-2.80) for joint space narrowing. When women with non-live birth pregnancies were excluded and latency was considered, increased risk of joint erosion (RR 2.57, 95%CI 1.12-5.92) and joint space narrowing (RR 2.97, 95%CI 1.18-7.44) were observed only for parous women with deliveries <15 years prior to RA diagnosis; no increased risks were observed for the other 5 outcome measures (number of affected joints, extra-articular disease, surgery, pain, and disability). If parity is associated with disease progression, our results suggest this relationship may be complex.