Ovulatory potential of preovulatory sized follicles during oral contraceptive treatment

The ovulatory potential of preovulatory follicles Mras studied in five women taking monophasic gestodene pills containing 20 mu g of ethinyl estradiol. After one normal pill cycle, follicles were allowed to grow to Ib mm in diameter by deliberate extension of the pill-free period. Once the size of the leading follicle reached 16 mm, the women resumed oral contraceptives for the following 21 days to investigate whether ovulation can be inhibited by late onset of the pill. In addition, 100 mu g of gonadotropin releasing hormone analog was given intravenously on the third pill day to induce ovulation. Follicular growth and activity were monitored by ultrasonography and by serum concentrations of ethinyl estradiol, progesterone, luteinizing hormone, and follicle stimulating hormone from the last pill day of the first cycle until the end of the second pill intake of 21 days. An increase in luteinizing hormone secretion started before intravenous administration of a gonadotropin releasing hormone analog in all women, eventually leading to ovulation in four of five women. One woman developed an unruptured follicle. Thus, the ovulatory potential of a 16-mm functional follicle cannot be inhibited by reintroduction of pills containing 20 mu g ethinyl estradiol and 75 mu g of gestodene. CONTRACEPTION 1999;60:275-279 (C) 1999 Elsevier Science Inc. All rights reserved.