Increased risk of rheumatoid arthritis in women with pregnancy complications and poor self-rated health: a study within the Danish National Birth Cohort.

OBJECTIVE: This study assessed the suggested association between pregnancy-associated hypertensive disorders, hyperemesis and subsequent risk of RA using a cohort with information about pre-pregnancy health. METHODS: Self-reported information on pre-pregnancy health, pregnancy course, gestational hypertension, pre-eclampsia and hyperemesis was available from 55 752 pregnant women included in the Danish National Birth Cohort. Information about pregnancy-related factors and lifestyle was obtained by interviews twice during pregnancy and at 6 months post-partum. Women were followed for RA hospitalizations identified in the Danish National Patient Register. Hazard ratios (HRs) and 95% CIs were calculated using Cox proportional hazards models. Women with RA and non-specific musculoskeletal problems at the time of pregnancy were excluded. RESULTS: On average, women were followed for 11 years after childbirth and 169 cases of RA were identified. The risk of RA was increased in women with pre-eclampsia (n = 11, HR = 1.96, 95% CI 1.06, 3.63), a poor self-rated pregnancy course (n = 32, HR = 1.63, 95% CI 1.11, 2.39) and fair or poor self-rated pre-pregnancy health (fair health: n = 86, HR = 1.52, 95% CI 1.11, 2.09; poor health: n = 14, HR = 3.24, 95% CI 1.82, 5.76). Hyperemesis was not associated with risk of RA. CONCLUSION: We confirmed the previously suggested increased risk of RA in women with pre-eclampsia and also found an inverse association between self-rated pre-pregnancy health and risk of RA. These results suggest that the clinical onset of RA is preceded by a prolonged subclinical phase that may interfere with women's general well-being and pregnancy course or that some women carry a shared predisposition to pre-eclampsia and RA.