Recurrent pregnancy loss and incident arthritis in midlife: an exploratory longitudinal analysis of the Study of Women's Health Across the Nation.

Purpose: To explore the association between recurrent pregnancy loss (RPL) and incident arthritis in midlife women.

Methods: We analyzed the U.S. Study of Women's Health Across the Nation, a multi-ethnic cohort following pre- or peri‑menopausal women, using data from baseline up to the tenth annual follow-up visit. Discrete survival analysis was used to estimate adjusted hazard ratios and 95% confidence intervals for risk of incident arthritis at annual intervals in women with versus without RPL.

Results: Of the 2159 participants analyzed, 8.5% reported a history of RPL. Cumulative incidence of arthritis was 43.3% in women with RPL and 40.1% in women without RPL, though differences between groups varied over time. Significant associations were observed only at visits three to seven, with the strongest associations at visits four to six. The adjusted hazard ratios (95% confidence intervals) were 1.80 (1.30-2.50) at visit 4 (median age = 50 years), 1.95 (1.38-2.75) at visit 5 (median age = 51 years), and 1.82 (1.28-2.58) at visit 6 (median age = 52 years).

Conclusions: Women with previous RPL may have elevated risk of arthritis specifically when entering their 50s, on average. Additional research is needed to determine whether women with a history of RPL may benefit from early detection of arthritis in midlife.