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Contraception. 1996 Aug;54(2):71-7.

Shorter pill-free interval in combined oral contraceptives decreases follicular development.

Author information

1
First Department of Obstetrics and Gynecology, University of Vienna, Austria.

Abstract

The objective of the study was to determine the suppressive effect on ovarian activity of 20 micrograms ethinylestradiol plus 75 micrograms gestodene administered for 21 or 23 days. The study was designed as a double-blind, randomized, multicenter trial in 60 women. A pre-treatment cycle, three treatment cycles and a post-treatment period were monitored by ovarian ultrasound and by LH, FSH, 17 beta-estradiol and progesterone measurements every other day. No ovulation and no luteinized, unruptured follicle were observed. Suppression of ovarian activity was more pronounced by the 23-day regimen. 17 beta-Estradiol serum levels during the last six days of a cycle and during the first six days of the next cycle were significantly less (p < 0.05) in the 23-day regimen. The superiority of the 23-day regimen in comparison to the 21-day regimen with regard to the suppression of ovarian activity was shown in this study. The observed differences in the 17 beta-estradiol levels and follicular development between a 21-day and 23-day preparation combine to suggest that shortening the pill-free interval in combined oral contraceptives may increase the contraceptive safety margin in women on low-dose formulations.

PIP:

The objective of a double-blind randomized multicenter trial enrolling 60 women was to determine the suppressive effect on ovarian activity of 20 mcg ethinyl estradiol plus 75 mcg gestodene administered for 21 or 23 days. The sites were at the Department of Obstetrics and Gynecology, University of Manchester, UK, and the Institute for Sterility Treatment, Vienna, Austria. The 60 women were healthy volunteers 19-35 years old, and they were randomized with 30 subjects each entering the treatment phase for either the 21-day regimen or the 23-day regimen. A pre-treatment cycle, 3 treatment cycles, and a post-treatment period were monitored by ovarian ultrasound and by measurements of luteinizing hormone (LH), follicle stimulating hormone (FSH), 17-beta-estradiol, and progesterone every other day. Two women on the 21-day regimen forgot to take 1 pill each. Side effects were minor including breast tension, vomiting, nausea, acne, and weight loss or weight gain. Withdrawal bleeding commenced in the 23-day group 2 days later than in the 21-day group. The frequency of intracyclic bleeding decreased when progressing from treatment cycle 1 to 3. No ovulation and no luteinized, unruptured follicle were observed. After stopping the medication, spontaneous ovulations were observed in all volunteers in the 23-day regimen. Suppression of ovarian activity was more pronounced in the 23-day regimen. 17-beta-estradiol serum levels during the last 6 days of a cycle and during the first 6 days of the next cycle were significantly less (p 0.05) in the 23-day regimen. The superiority of the 23-day regimen in comparison to the 21-day regimen with regard to the suppression of ovarian activity was shown. The observed differences in the 17-beta-estradiol levels and follicular development between the 21-day and 23-day preparations suggest that shortening the pill-free interval in combined oral contraceptives may increase the contraceptive safety margin in women on low-dose formulations.

PMID:
8842582
[Indexed for MEDLINE]

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