title: Risk of pregnancy among women seeking emergency contraceptives from pharmacists in British Columbia.
abstract: OBJECTIVE
  Recent revision of the method used to estimate risk of pregnancy among women requesting medication for emergency contraception (EC) suggests that the effectiveness of EC may be lower than is generally believed. We undertook a population-based study to estimate the risk of pregnancy among women requesting EC from pharmacists in British Columbia under conditions of routine care.
  
  
  METHODS
  We obtained data on time since unprotected intercourse and medication provided for women in British Columbia requesting EC from January 1, 2001 to December 31, 2002.
  
  
  RESULTS
  More women obtained levonorgestrel (60.7%) than the Yuzpe regimen (39.3%) for EC, and of those reporting contraceptive failure, 90% requested EC because of condom failure. Overall, the estimated risk of pregnancy among the 11 795 women who obtained EC was 4.12 % (95% confidence interval 3.77-4.49).
  
  
  CONCLUSIONS
  Under routine conditions, the population-based predicted risk of pregnancy is lower than has previously been estimated. This suggests that the relative reduction in pregnancies achieved with EC is lower than is currently assumed by clinicians and patients.
authors.affiliation: Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver BC; Department of Pharmacy, Children's and Women's Hospitals of British Columbia, Vancouver BC.
authors.forename: Marc
authors.initials: M
authors.lastname: Levine
authors.affiliation: Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver BC.
authors.forename: Judith A
authors.initials: JA
authors.lastname: Soon
mesh_terms: D000328:Adult; D003267:Contraception / Q000379:methods* / Q000706:statistics & numerical data; D003281:Contraceptives, Postcoital / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D012307:Risk Factors; D013997:Time Factors; D017211:Treatment Failure; D016896:Treatment Outcome
chemical_list: D003281:Contraceptives, Postcoital