title: Increased risk of rheumatoid arthritis in women with pregnancy complications and poor self-rated health: a study within the Danish National Birth Cohort.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Department of Occupational and Environmental Medicine, Bispebjerg Hospital and Department of Rheumatology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.Department of Epidemiology Research, Statens Serum Institut, Department of Occupational and Environmental Medicine, Bispebjerg Hospital and Department of Rheumatology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark. kristian.tore.joergensen@regionh.dk.
authors.forename: Kristian Tore
authors.initials: KT
authors.lastname: Jørgensen
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Department of Occupational and Environmental Medicine, Bispebjerg Hospital and Department of Rheumatology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Harpsøe
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Department of Occupational and Environmental Medicine, Bispebjerg Hospital and Department of Rheumatology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Jacobsen
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Department of Occupational and Environmental Medicine, Bispebjerg Hospital and Department of Rheumatology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Tine
authors.initials: T
authors.lastname: Jess
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Department of Occupational and Environmental Medicine, Bispebjerg Hospital and Department of Rheumatology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Frisch
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000453:epidemiology* / Q000209:etiology; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006304:Health Status; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D012306:Risk; D057566:Self Report; D055815:Young Adult
keywords: pre-eclampsia; pregnancy; rheumatoid arthritis; self-rated health