Continuous combination oral contraceptive pills to eliminate withdrawal bleeding: a randomized trial

Obstet Gynecol. 2003 Apr;101(4):653-61. doi: 10.1016/s0029-7844(03)00014-0.


Objective: To compare bleeding profiles of a traditional 28-day oral contraceptive pill cycle with continuous administration.

Methods: After a 28-day run-in cycle, women were randomized to either 28-day cycles (21 active pills and a pill-free week) or continuous use of the same 20 microg ethinyl estradiol/100 microg levonorgestrel formulation for 12 study cycles (336 days). The number of bleeding and spotting days were measured by daily diary. A subset underwent cycle 1 (n = 16), and nine (n = 14) pelvic ultrasound and endometrial histology sampling. Blood pressure, weight, hemoglobin, and adverse events were measured at revisit. The sample size with 80% power to detect a 67% reduction in bleeding days required 27 subjects in each arm.

Results: Of the 79 subjects randomized, 28 (70%) of the 28-day cycle and 32 (82%) of the continuous-use subjects completed the entire study (P =.6). With continuous use, 49%, 68%, and 88% of women reported no bleeding during cycles 2, 6, and 12, respectively. Amenorrhea or infrequent bleeding was present in 68% of continuous users during cycles 1-3 and increased to 88% during cycles 10-12. Spotting during cycle days 1-21 increased initially with continuous use but reduced over time, and by 9 months was less than the spotting reported by cyclic users. Adverse events, blood pressure, weight, and hemoglobin findings were similar between groups.

Conclusion: Extension of the 28-day oral contraceptive cycle to continuous use with a low-estrogen dose combination oral birth control pill resulted in significantly fewer bleeding days.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Contraceptives, Oral, Combined / administration & dosage*
  • Drug Administration Schedule
  • Endometrium / diagnostic imaging
  • Endometrium / pathology
  • Ethinyl Estradiol / administration & dosage*
  • Female
  • Humans
  • Levonorgestrel / administration & dosage*
  • Menstrual Cycle / drug effects*
  • Treatment Outcome
  • Ultrasonography
  • Uterine Hemorrhage / prevention & control*


  • Contraceptives, Oral, Combined
  • Ethinyl Estradiol
  • Levonorgestrel