A new model for ovarian follicular development during the human menstrual cycle

OBJECTIVE: To evaluate changes in ovarian follicle dynamics during the human menstrual cycle to test the hypothesis that folliculogenesis occurs in a wave-like fashion. DESIGN: Prospective longitudinal study. SETTING: Healthy volunteers in an academic research environment. PATIENT(S): Fifty healthy women of reproductive age (range 19-43 years) with a history of regular menstrual cycles not taking medications known to interfere with reproductive function were evaluated. INTERVENTION(S): Transvaginal ultrasonography was performed daily for one interovulatory interval (IOI). MAIN OUTCOME MEASURE(S): Changes in the diameter and number of follicles > or =5 mm were evaluated. RESULT(S): Sixty-eight percent of women exhibited two waves of follicle development during the IOI and 32% exhibited three waves. Waves were characterized by an increase and subsequent decrease in the number of follicles > or =5 mm occurring in association with the growth of > or =2 follicles to > or =6 mm. A day effect and day by wave interaction were detected in the mean diameter of the largest three follicles and the number of follicles > or =5 mm. CONCLUSION(S): The follicular wave phenomenon in women provides a new model for ovarian function during the menstrual cycle and will improve our understanding of the ovarian response to fertility and hormonal contraceptive regimens.