title: Contraception and unexplained abdominal pain.
abstract: OBJECTIVE
  To test the hypothesis that hospital referral for unexplained abdominal pain might occur less frequently in oral contraceptive (OC) users and more frequently in intrauterine device (IUD) users than in other women.
  
  
  METHODS
  Prospective cohort study of 17 032 women using different methods of contraception [the Oxford-Family Planning Association (FPA) contraceptive study].
  
  
  METHODS
  Referral to hospital for unexplained abdominal pain (including pelvic pain) coded to ICD rubric 785.5 in the 8th Revision of the ICD.
  
  
  RESULTS
  Referral was decreased by 13% (95% CI 0%-25%) in current or recent users of OCs in comparison with non-users, a difference that just reached statistical significance. No significant difference was found in the corresponding analysis for IUD users. Past users of OCs had much the same risk of referral as non-users, but the risk of referral in past users of an IUD was increased at all intervals examined, varying from 17% (95% CI -14%-55%) 13-24 months after discontinuation to 56% (95% CI 15%-107%) 73-96 months after discontinuation. Referral was 29% (95% CI 11%-50%) higher in smokers of 15 or more cigarettes a day than in non-smokers.
  
  
  CONCLUSIONS
  Referral to hospital for unexplained abdominal pain may be slightly reduced in current or recent OC users and moderately increased in past IUD users. The types of IUD used most commonly in the Oxford-FPA study are, however, no longer in current use today. Hospital referral for unexplained abdominal pain seems to be moderately increased in heavy cigarette smokers.
authors.affiliation: Unit of Health Care Epidemiology, Oxford University Department of Public Health, Institute of Health Sciences, Headington, Oxford, UK. martin.vessey@dphpc.ox.ac.uk
authors.forename: Martin
authors.initials: M
authors.lastname: Vessey
authors.forename: Rosemary
authors.initials: R
authors.lastname: Painter
mesh_terms: D015746:Abdominal Pain / Q000139:chemically induced / Q000175:diagnosis / Q000209:etiology*; D000328:Adult; D003276:Contraceptives, Oral / Q000009:adverse effects*; D005260:Female; D006760:Hospitalization; D006801:Humans; D007434:Intrauterine Devices / Q000009:adverse effects*; D011446:Prospective Studies; D012017:Referral and Consultation; D018570:Risk Assessment; D012307:Risk Factors
chemical_list: D003276:Contraceptives, Oral