title: Decreased fertility rates in 9639 women diagnosed with inflammatory bowel disease: a United Kingdom population-based cohort study.
abstract: BACKGROUND
  Clinical studies have reported reduced fertility in women with inflammatory bowel disease (IBD).
  
  
  OBJECTIVE
  To compare fertility rates in women with IBD to those in women without IBD and assess whether the relative fertility differed following IBD diagnosis, flares and surgery.
  
  
  METHODS
  Women aged 15-44 years in 1990-2010 were identified from a UK primary care database. We estimated overall and age-specific fertility rates by 5-year age bands for women with and without IBD. We used Poisson regression to calculate adjusted fertility rate ratios (AFRR), adjusted for age, smoking and socioeconomic deprivation.
  
  
  RESULTS
  There were 46.2 live births per 1000 person-years [95% confidence interval (95% CI); 44.6-47.9] in 9639 women with IBD and 49.3 (95% CI 49.2-49.5) in 2 131 864 without (AFRR: 0.93; 95% CI: 0.89-0.96). Excluding periods of contraception use, the AFRR was 0.99 (95% CI: 0.95-1.03). Before diagnosis, the AFRR for women with ulcerative colitis (UC) was 1.07 (95% CI: 0.99-1.16) and was 0.88 (95% CI: 0.81-0.97) for women with CD. After diagnosis, AFRRs were 0.87 (95% CI: 0.82-0.94) for CD and 0.92 (95% CI: 0.86-1.00) for UC. The fertility rate was lower following flares (AFRR: 0.70; 95% CI: 0.59-0.82) or surgery (AFRR: 0.84; 95% CI: 0.77-0.92). Women with pouch and non-pouch surgery had similar overall fertility though the reduction after surgery was greater for pouches (AFRR: 0.48; 95% CI: 0.23-0.99).
  
  
  CONCLUSIONS
  Women with Crohn's disease have marginally lower fertility rates. These rates decreased following flares and surgical interventions. Fertility rates returned almost to normal when women were not prescribed contraception but the reduction following surgical intervention remained. As the lifetime effect of pouch vs. nonpouch surgery on fertility is small, the reduction post-pouch surgery should be interpreted with caution.
authors.affiliation: Division of Epidemiology & Public Health, University of Nottingham, Nottingham, UK.
authors.forename: L
authors.initials: L
authors.lastname: Ban
authors.affiliation: Division of Epidemiology & Public Health, University of Nottingham, Nottingham, UK.
authors.forename: L J
authors.initials: LJ
authors.lastname: Tata
authors.affiliation: Division of Epidemiology & Public Health, University of Nottingham, Nottingham, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Humes
authors.affiliation: Division of Epidemiology & Public Health, University of Nottingham, Nottingham, UK.
authors.forename: L
authors.initials: L
authors.lastname: Fiaschi
authors.affiliation: Division of Epidemiology & Public Health, University of Nottingham, Nottingham, UK.
authors.forename: T
authors.initials: T
authors.lastname: Card
mesh_terms: D000293:Adolescent; D000328:Adult; D001723:Birth Rate / Q000639:trends*; D015331:Cohort Studies; D003093:Colitis, Ulcerative / Q000150:complications / Q000453:epidemiology; D003424:Crohn Disease / Q000150:complications / Q000453:epidemiology; D016208:Databases, Factual; D005260:Female; D005298:Fertility / Q000502:physiology*; D006801:Humans; D007247:Infertility, Female / Q000150:complications / Q000453:epidemiology*; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000453:epidemiology*; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult