Extended Combined Oral Contraceptives: Do They Work?

Peter Kovacs, MD, PhD


January 28, 2010

The Efficacy and Safety of a Low-Dose, 91-Day, Extended-Regimen Oral Contraceptive With Continuous Ethinyl Estradiol

Kroll R, Reape KZ, Margolis M
Contraception. 2010;81:41-48


Numerous contraceptive methods (calendar, barrier, surgical, and hormonal) are available. Hormonal and surgical methods are the most popular and, when used properly, are associated with high efficacy. Hormonal methods include progestin-only or, more commonly, combined preparations. Combined preparations contain both estradiol and progestin. Over the years, the combined oral contraceptive pill has undergone several important changes. First, the dose of the estradiol component (ethinyl estradiol) was reduced significantly. This has led to improved safety and fewer side effects. Later, the progestin component was changed to new progestins with improved tolerance profiles. Traditionally, the pill regimen follows the course of a spontaneous menstrual cycle, and cyclic withdrawal bleeding occurs every 28 days. To better manage certain medical problems (eg, premenstrual symptoms, menorrhagia, endometriosis), extended pill use that does not involve monthly withdrawal bleeding has been evaluated. Most users would desire less frequent menstrual bleeding with the maintenance of efficacy and a favorable side effect profile. This study evaluated the efficacy and side effect profile of a low-dose, extended-regimen oral contraceptive pill.

Study Summary

The study drug contained ethinyl estradiol (20 µg) and levonorgestrel (100 µg). The regimen consisted of 84 hormonally active pills followed by 7 days' worth of pills containing only ethinyl estradiol. The study lasted for 14 months, which included a 1-month pretreatment evaluation cycle, 12-month-long study cycles, and a posttreatment evaluation cycle. Reproductive-aged women who were at risk for pregnancy and had no contraindication to hormone use were recruited, and 2235 women were enrolled. Of these, 2185 took at least 1 dose of the study drug and 1249 completed the entire study. Contraceptive efficacy, bleeding pattern, and side effect profile were assessed. During the entire study period, 36 pregnancies were reported. The Pearl index was 2.74 overall and 1.73 among women adherent to the regimen. An important finding was that body mass index had no effect on efficacy. Bleeding or spotting was self-reported. Scheduled and unscheduled bleeding episodes were most common during the first 91 days, and the incidence continuously decreased during the study period. The mean number of unscheduled bleeding days was 5 during the first 91-day cycle and 0 during cycles 3 and 4. During the first cycle, the mean number of days with spotting was 10, but this was reduced to 3 days by cycle 4. Laboratory values and weight did not change significantly during the study period. Reported side effects were similar to those with a 28-day pill schedule.


Hormonal contraception is effective, is associated with few side effects, and has noncontraceptive benefits as well. Extended pill use was first evaluated in cases when monthly withdrawal bleeding was undesirable. Women with severe dysmenorrhea, bleeding disorders, and recurring premenstrual symptoms do benefit from less frequent menstruation. However, some "regular" users of oral contraceptive pills would also prefer fewer bleeding episodes. This multicenter, open-label, single-treatment study evaluated extended use of a low-dose oral contraceptive pill among healthy reproductive-aged women. No serious side effects occurred with extended pill use. Previous studies have shown that extended pill use has no negative effect on the endometrium; in fact, it led to inactive endometrium.[1] Adherence with the study drug was similar to that seen in previous studies of oral contraceptives.

Bleeding and spotting episodes are most common during the first few months of use. The patient needs to be educated about this side effect because many women discontinue the pill during the first few months because of concerns about the irregular bleeding. As with monthly use, the frequency of unscheduled bleeding or spotting was reduced with prolonged use of the extended regimen. Overall, an acceptable failure rate was seen with the extended regimen.

When a woman plans to use oral contraceptives for years, the extended regimen, with its less frequent and smaller amount of bleeding, may be an attractive choice. Women who have painful menstruation or heavy bleeding would also benefit from this regimen. The extended regimen could also benefit someone given a diagnosis of endometriosis or ovarian cysts. The use of low-dose estrogen should lead to lower risk for venous thromboembolism and may be associated with a more favorable cardiovascular profile. The efficacy appears to be maintained despite the extended use and the lower estrogen dose. Because up to half of all pregnancies are unplanned and at least half of unplanned pregnancies are terminated, any favorable change with regard to contraceptive methods is welcome.[2] The extended, low-dose pill regimen appears to be an important addition to women's contraceptive choices.



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