To overcome unsuitable effects of controlled ovarian hyperstimulation (COH )while maintaining
large oocyte availability, investigators elaborated an innovative protocol (NATural Ovarian
Stimulation) that dissociates E2 production from multiple follicle development.
The purpose of this prospective, randomized trial is to demonstrate that, in a good prognosis
IVF-ET population, the physiological E2 environment resulting from NATOS significantly
improves IVF-ET outcome when compared to the conventional GnRH antagonist protocol.