Progesterone is a physiological trigger of ovulatory gonadotropins
Article In Press
Dmitri Dozortsev, M.D., Ph.D., Antonio Pellicer, M.D., Michael P. Diamond, M.D.
The process of ovulation in the human is central not only to the field of infertility, but to obstetrics and gynecology in general, and has been a subject of thousands of research projects for more than a century. The holy grail of ovulation is the mechanism triggering the surge of gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which according to the current paradigm is caused by a critically timed, sustained elevation of estradiol that culminates in the end of the follicular phase of the menstrual cycle. However, a recent prospective, randomized study has clearly demonstrated that continued administration of letrozole throughout the follicular phase, with well documented suppression of estradiol, did not have any effect on the timing of ovulation in normally menstruating women. This observation led authors to conclude that the role of estradiol (E2) in ovulation has been “misinterpreted” (1).