title: Continued use of the Standard Days Method.
abstract: OBJECTIVE
  To examine the long-term effectiveness and continuation of the Standard Days Method (SDM)®, a fertility awareness-based method of family planning that identifies Days 8-19 (inclusive) of the cycle as the fertile window. On these days users avoid unprotected sexual intercourse to prevent pregnancy. The method works best for women with cycles that are usually in the range of 26-32 days, which is an important reason for method discontinuation in the first year of use. The authors determine if this continues to be an issue in the second and third years of method use.
  
  
  METHODS
  Participants in an earlier efficacy study (478 women in three countries) and method introduction studies (1181 women in four countries) were followed for 2 years beyond the original 1-year study period, to determine their continued use of the method, intended and unintended pregnancies, and reasons for discontinuation. Life-tables were used to approximate typical use pregnancy rates.
  
  
  RESULTS
  The method continues to be effective in the second and third years of use, and compares favourably to other user-directed family planning methods. Women with no more than two cycles outside the 26-32-day range within a year are likely to continue having cycles within this range.
  
  
  CONCLUSIONS
  Women who complete the first year of SDM use are likely to continue to be able to use the method successfully and effectively. The method presents a viable longer-term option for women who prefer this approach to family planning.
authors.affiliation: Institute for Reproductive Health, Georgetown University, Washington, DC., USA. sinaii@georgetown.edu
authors.forename: Irit
authors.initials: I
authors.lastname: Sinai
authors.forename: Rebecka I
authors.initials: RI
authors.lastname: Lundgren
authors.forename: James N
authors.initials: JN
authors.lastname: Gribble
mesh_terms: D005260:Female; D006801:Humans; D008597:Menstrual Cycle / Q000502:physiology*; D012252:Natural Family Planning Methods / Q000379:methods*; D012111:Residence Characteristics; D012959:Socioeconomic Factors; D013997:Time Factors