To compare a traditional 28-day cycle to an extended 49-day cycle of the 30 μg ethinyl estradiol (E2)/300 μg norgestrel monophasic birth control pill regimen.
Ninety subjects randomized to either 28-day cycles with 21 active pills or 49-day cycles with 42 active pills for a prospective open label trial over four 84-day reference periods or trimesters. Bleeding, pill taking, and symptom diaries were completed. The sample size with 80% power to detect a 40% reduction in bleeding days required 24 subjects in each arm.
Of the 90 women, 24 subjects (54.5%) on the 28-day cycle and 29 (63%) on the 49-day cycle completed the entire study (P = .41). There were no statistically significant differences between the two groups in demographics or continuation rates. There was a significant reduction in bleeding days in the experimental arm beginning in the first trimester (28-day = 10.9, 49-day = 6.4 mean days of bleeding, P < .001) and continuing to the fourth trimester (28-day = 11.3, 49-day = 5.8 mean days, P = .005). The number of spotting days was similar between both schedules in the first trimester (28-day = 4.8, 49-day = 3.7 mean days, P = .24) and continued into the fourth trimester (28-day = 3.4, 49-day = 2.9 mean days, P = .30). Annual expenditure for hygiene products was significantly less for extended use subjects (28-day = $41.45, 49-day = $17.54 spent, P < .001).
Extension of the 28-day oral contraceptive (OC) cycle to a 49-day cycle resulted in fewer bleeding days and no increase in mean spotting days or bleeding episodes.
Extension of a monophasic oral contraceptive regimen from 28-day to 49-day cycles significantly decreases bleeding and hygiene product use without increased spotting.
Department of Obstetrics and Gynecology, University of Washington School of Medicine, Seattle, Washington.
Address reprint requests to: Leslie Miller, MD, 325 Ninth Ave, Seattle, WA 98104–2499; E-mail: firstname.lastname@example.org.
Parke-Davis Women's Healthcare Research Award supported by The American College of Obstetricians and Gynecologists, 1997.
Study medication supplied by Wyeth-Ayerst Laboratories, Philadelphia, Pennsylvania.
The authors thank Elizabeth Pulos for her thoughtful and careful statistical advice and support.
Financial Disclosure: Author Miller received financial assistance and research support from Wyeth-Ayerst Laboratories and is a member of the company's speakers bureau.
Received February 16, 2001. Received in revised form June 11, 2001. Accepted July 16, 2001.