Effects of Letrozole During the Luteal Phase After Controlled Ovarian Stimulation in Oocyte Donors.

The objective of this trial is to determine whether the use of letrozole during the luteal phase in oocyte donors diminishes the ovarian volume, as well as to evaluate its effect on the duration of the luteal phase, taking into account hormonal and biochemical markers. Two groups will be established with random allocation of patients and 1:1 proportionality, as follows: * Control group: No specific treatment. * Study group: Oral administration of letrozole 5 mg (each capsule is 2.5 mg) once a day for 5 days starting on the night of the follicular puncture.