Author(s): Zbigniew Szymoniak (ABCD), Robert Zawrotniak (B), Marcin Korman (DEF), Martyna Si?kowska (B), Mateusz Trzci??ki (A), Agnieszka Mitkowska (B), Robert Spaczy?ski5 (D), Leszek Pawelczyk5 (AG), Beata Banaszewska5 (AD)
Introduction. Oral contraceptive pills are based on two fundamental compositional formulas: pills with estrogens and progestins as well as pills with progestins alone. The study was conducted to evaluate ovarian function during the use of oral contraception by comparing 5 products differing in the dose of ethinyloestradiol (EE) and the type of progestin. Material and methods. It was a single-center, open-label, comparative study conducted in 89 healthy women divided into five groups: group 1: 0.03 mg of EE + 0.075 mg of gestodene (GSD), group 2: 0.03 mg of EE + 0.15 mg desogestrel (DGS), group 3: 0.02 mg of EE + 0.15 mg of DGS, group 4: 0.035 mg of EE + 0.25 mg of norgestimate (NGS), group 5: a triphasic preparation with 0.03–0.04 mg of EE + 0.05–0.125 mg of levonorgestrel (LNG). The 21+7 regimen was followed. On days 1–2 and 20–21 of the cycle, the number and diameter of ovarian follicles as well as endometrial thickness were measured with ultrasound. Moreover, estradiol and FSH concentrations were determined. Results. There were no significant differences in estradiol levels between the groups. However, the mean FSH level on day 20–21 of the cycle in group 4 was significantly higher (p = 0.006) than the mean levels observed in groups 1, 2 and 5. The greatest number of ovarian follicles was found in group 5 (16.4), and the lowest in group 3 (12.6), but these differences were not statistically significant. Moreover, differences were also noticed in the diameter of follicles on day 1–2. The mean value in group 5 (4.6 mm) was significantly higher than in the remaining groups: 3.6 mm, 3.4 mm, 3.3 mm and 3.4 mm, respectively. The endometrium on day 20–21 of the cycle was the thickest in group 5 (7.2 mm) and was significantly thicker than in all the remaining groups (p = 0.000005). Conclusions. All the tested products prevented ovulation in an effective way when used correctly. However, the level of follicular suppression and endometrial growth differed across the groups. Combined triphasic oral contraceptive pills with 30–40 μg of EE and 50–125 μg of LNG were characterized by lower suppressive capability than the products with lower EE doses. It can be suspected that the level of follicular suppression does not depend only on the EE dose, but also on the type of progestin, but the precise mechanism underlying this phenomenon remains unclear.