Long-term safety of an extended-cycle oral contraceptive (Seasonale): a 2-year multicenter open-label extension trial

Am J Obstet Gynecol. 2006 Jul;195(1):92-6. doi: 10.1016/j.ajog.2005.12.045. Epub 2006 Apr 21.


Objective: The purpose of this study was to assess the long-term safety of Seasonale, 91-day extended-cycle oral contraceptive (OC).

Study design: Following completion of a 1-year Phase 3 multicenter trial, patients from selected centers were invited to participate in this 2-year extension trial. In this open-label study all participants received the 91-day extended-regimen OC, Seasonale.

Results: There were 189 study participants enrolled from 27 sites. Patient exposure included 1130 completed 91-day cycles. Overall rates of study discontinuation and the incidence of adverse events were similar to the earlier Phase 3 clinical trial. Seasonale was well tolerated and the number of reported bleeding and/or spotting days reported diminished during the course of the study.

Conclusion: This study confirms the findings from the previous clinical trial and demonstrates that Seasonale is a safe and effective therapy for long-term use.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Contraceptives, Oral, Combined / administration & dosage*
  • Contraceptives, Oral, Combined / adverse effects
  • Ethinyl Estradiol-Norgestrel Combination / administration & dosage*
  • Ethinyl Estradiol-Norgestrel Combination / adverse effects
  • Female
  • Humans
  • Menstruation / drug effects


  • Contraceptives, Oral, Combined
  • Seasonale
  • Ethinyl Estradiol-Norgestrel Combination