title: Oral contraceptive effectiveness according to body mass index, weight, age, and other factors.
abstract: OBJECTIVE
  The purpose of this study was to assess the use-effectiveness of oral contraceptives (OCs) in Europe according to body mass index (BMI), weight, age, and other factors.
  
  
  METHODS
  In a planned secondary analysis, we used data from the European Active Surveillance Study on Oral Contraceptives, which was a prospective active cohort surveillance study of 59,510 OC users, to assess the effectiveness of OCs overall and by BMI, weight, age, duration of use, ethinylestradiol dose, regimen type, starting/switching status, and parity. Self-reported unplanned pregnancies during OC use were confirmed by interview.
  
  
  RESULTS
  An analysis of OC effectiveness (112,659 women-years of exposure and 545 unplanned pregnancies) found little variation in effectiveness by BMI/weight. Failure rates decreased after 30 years of age and with an increasing duration of use.
  
  
  CONCLUSIONS
  OC users in Europe reported high contraceptive effectiveness with "typical use." Failure rates decreased with age and duration of use. BMI and weight had little, if any, influence on effectiveness.
authors.affiliation: ZEG-Center for Epidemiology and Health Research, Berlin, Germany. dinger@zeg-berlin.de
authors.forename: Jürgen C
authors.initials: JC
authors.lastname: Dinger
authors.forename: Maureen
authors.initials: M
authors.lastname: Cronin
authors.forename: Sabine
authors.initials: S
authors.lastname: Möhner
authors.forename: Ilka
authors.initials: I
authors.lastname: Schellschmidt
authors.forename: Thai Do
authors.initials: TD
authors.lastname: Minh
authors.forename: Carolyn
authors.initials: C
authors.lastname: Westhoff
mesh_terms: D000367:Age Factors; D015992:Body Mass Index; D001835:Body Weight; D003276:Contraceptives, Oral / Q000494:pharmacology; D005060:Europe; D005260:Female; D006801:Humans; D015993:Life Tables; D049168:Pregnancy, Unplanned; D012307:Risk Factors; D013997:Time Factors; D017211:Treatment Failure
chemical_list: D003276:Contraceptives, Oral