RENO, NEV. — Patients taking extended-cycle oral contraceptives had about the same number of total bleeding days over 6 months as women taking a standard, 28-day oral contraception regimen but had significantly fewer days of moderate to heavy bleeding.
“There is lower serum and urinary estrogen, [as well as] smaller ovaries and follicles, thinner endometrium, and improved patient symptomatology with a continuous oral contraceptive pill regimen,” Dr. Richard S. Legro reported at the annual meeting of the Society for Gynecologic Investigation.
The findings support the use of extended cycle suppression with oral estrogen (20 mcg) and progestin norethindrone acetate (1 mg) in a continuous regimen for indications such as endometriosis, hirsutism, and acne, Dr. Legro said at the meeting, where he presented the findings in poster form.
No pharmaceutical companies contributed funding for the study, which was financed in part by the National Institutes of Health, said Dr. Legro, a reproductive endocrinologist at Pennsylvania State University in Hershey, Pa.
Dr. Legro and his coinvestigators enrolled 62 normally cycling women in a double-blind, randomized, controlled trial and followed them for symptoms, bleeding patterns, endometrial histology, follicular development, and serum and urinary levels of sex steroids as they took oral contraceptives for 28 days per month with the traditional 7-day pill-free interval or continuously.
The number of moderate to heavy bleeding days dropped to 1 day/month or less by cycle 2 in the continuous OC group, decreasing more slowly over time in women taking the 28-day OC regimen.
Women taking continuous OC pills had a 25%–30% greater suppression of serum estrogen levels than those on the 28-day regimen. Total ovarian volume, maximum diameter of the largest follicle, and endometrial thickness were all reduced significantly more in patients on the continuous regimen. Scores on premenstrual pain, behavior, and distress scales were also lower for women assigned to receive continuous OC pills.