title: Increased access to emergency contraception: why it may fail.
abstract: BACKGROUND
  To explore why increased access to emergency contraception (EC) failed to reduce pregnancies in a recent randomized controlled trial.
  
  
  METHODS
  We used multivariable logistic regression to identify risk factors for unintended pregnancy using data from a trial involving sexually active women (n = 1490, aged 14-24 years) randomly assigned to either increased access or standard access to EC. We used predictive modeling to generate estimated pregnancy risk scores for each participant. We then examined EC use among women at low or high baseline risk of pregnancy.
  
  
  RESULTS
  Gravidity, recent history of unprotected sex (within 14 days of enrollment to study) and lower aversion to pregnancy predicted unintended pregnancy. Women in the increased access group were more likely than women in the standard access group to use EC repeatedly. This difference was significantly stronger (P = 0.03) among low risk women than high risk women [Relative risk (RR) 10.0, 95% confidence interval (CI) 6.5-15.4 and RR 5.5, 95% CI 3.8-7.9, respectively].
  
  
  CONCLUSIONS
  Increased access to EC had a greater impact on women who were at lower baseline risk of pregnancy. This may explain in part why increased access to EC has had no measurable benefit in clinical trials.
authors.affiliation: Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, 101 Manning Drive, CB #7570, Chapel Hill, NC 27514, USA. lbaecher@hotmail.com
authors.forename: Laura
authors.initials: L
authors.lastname: Baecher
authors.forename: Mark A
authors.initials: MA
authors.lastname: Weaver
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Raymond
mesh_terms: D000293:Adolescent; D044363:Contraception, Postcoital / Q000706:statistics & numerical data* / Q000639:trends; D003281:Contraceptives, Postcoital / Q000008:administration & dosage; D005260:Female; D006297:Health Services Accessibility / Q000706:statistics & numerical data; D006801:Humans; D016015:Logistic Models; D011247:Pregnancy; D012307:Risk Factors; D014481:United States; D055815:Young Adult
chemical_list: D003281:Contraceptives, Postcoital