title: Implications of cycle length immediately after discontinuation of combined oral contraceptives on use of the Standard Days Method.
abstract: OBJECTIVE
  To determine when after discontinuing the use of combined oral contraceptives (COC) women can start using the Standard Days Method (SDM)-a fertility awareness-based family-planning method that is appropriate only for women for whom most menstrual cycles last 26-32 days.
  
  
  METHODS
  We reviewed data from the medical records of women who attended the Human Reproduction Unit at the University of Campinas, Brazil, between October 16, 1979, and May 5, 2006. The study population comprised women younger than 40 years of age who had recently switched from COC to copper intrauterine devices and whose clinical records contained the information necessary for determining the length of the first menstrual cycle immediately after discontinuing COC.
  
  
  RESULTS
  In total, 47.2% of the 2845 women included in the study had a first post-COC cycle of 26-32 days; 40.5% had a second cycle within that range.
  
  
  CONCLUSIONS
  A first post-COC cycle within the 26-32-day range did not predict a second cycle within range. Women discontinuing COC should not start using the SDM in their first or second post-COC cycle, even if the first cycle falls within the stated range. Instead, they should use a backup method until they meet the necessary eligibility criteria.
authors.affiliation: United States Agency for International Development, Dhaka, Bangladesh.
authors.forename: Marcos
authors.initials: M
authors.lastname: Arévalo
authors.forename: Irit
authors.initials: I
authors.lastname: Sinai
authors.forename: Bruna
authors.initials: B
authors.lastname: Olivotti
authors.forename: Luis
authors.initials: L
authors.lastname: Bahamondes
mesh_terms: D000293:Adolescent; D000328:Adult; D001938:Brazil; D003267:Contraception / Q000379:methods; D003268:Contraception Behavior; D003277:Contraceptives, Oral, Combined / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007435:Intrauterine Devices, Copper; D008597:Menstrual Cycle / Q000187:drug effects*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D003277:Contraceptives, Oral, Combined