This study was performed to evaluate pituitary-ovarian recovery in the pill-free interval during use of three low-dose combined oral contraceptives (COC). Either the estrogen component or the progestin component was comparable in the study groups, to evaluate their relative influence. Serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol (E2) levels were measured and follicle number and size estimated by transvaginal sonography daily during the 7-day pill-free interval in 44 healthy volunteers using three different low-dose oral contraceptives. Healthy volunteers were enrolled using 20 micrograms ethinyl estradiol (EE) + 75 micrograms gestodene (GSD) (Harmonet, Wyeth-Lederle; n = 15), 20 micrograms EE + 150 micrograms desogestrel (DSG) (Mercilon, Organon n = 17), or 30 micrograms EE + 150 micrograms DSG (Marvelon, Organon, n = 12) given according to the usual regimen of one tablet daily during 3 weeks and 1 week pill-free interval. No ovulations were observed. Pituitary hormones were not statistically significantly different at the beginning of the pill-free interval between the study groups. FSH concentrations were significantly higher at the end of the pill-free interval in the 30 micrograms EE group compared with both 20 micrograms EE groups (7.0 [0.6-12.4] IU/L vs 4.9 [1.4-6.1] IU/L and 4.5 [2.4-7.4] IU/L; p = 0.001). In both 20 micrograms EE groups, a single persistent follicle (24 and 28 mm) was present in one subject. Follicle diameters were statistically significantly smaller at the beginning and at the end of the pill-free period in the 30 micrograms EE group compared with both 20 micrograms EE study groups. Dominant follicles (defined as follicle diameter > or = 10 mm) were observed at the end of the pill-free interval in both 20 micrograms EE groups (in 27% and 18% of women, respectively) but not in the 30 micrograms EE group. Finally, the area-under-the-curve for E2 was statistically significantly lower in the 30 micrograms EE group compared with both 20 micrograms EE groups. In conclusion, the EE content rather than the progestin component in the studied COC determined the extent of residual ovarian activity at the beginning of the pill-free interval. Dominant follicles were encountered only in the 20 micrograms EE study groups.
PIP: This article reports on a study that evaluated pituitary-ovarian recovery in the pill-free interval during a period of use of one of three low-dose combined oral contraceptives (COC). 44 female volunteers using low-dose oral contraception were subdivided into three groups in this comparative study: 15 women used 20 mcg ethinyl estradiol (EE) + 75 mcg gestodene; 17 used 20 mcg EE + 150 mcg desogestrel; 12 used 30 mcg EE + 150 mcg desogestrel. No ovulations were observed. Pituitary hormone levels between the study groups were not significantly different at the beginning of the pill-free interval. Follicle-stimulating hormone (FSH) concentrations were significantly higher at the end of the pill-free interval in the 30 mcg EE group than in both 20 mcg EE groups. In each of the 20 mcg EE groups, a single persistent follicle (24 mm and 28 mm, respectively) was found in 1 subject. In conclusion, the EE content rather than the progestin component in the studied COC determined the extent of residual ovarian activity at the beginning of the pill-free interval.