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

Letrozole is a widely used drug in the context of hormone-dependent malignant tumors due to its antiestrogenic effect. Its mechanism of action allows its application to the field of Assisted Reproductive Medicine, mainly as an inductor of ovulation, by means of a blockage in the negative feedback signalization of the hypothalamus-pituitary-gonadal axis. In the last years, it has also been tested with the goals of preventing ovarian hyperstimulation syndrome (OHSS) or analyzing its effects on several endocrinological and biochemical markers such as LH, progesterone or VEGF. However, the results are inconsistent on every account. Data regarding the effect on ovarian size and the duration of the luteal phase following the administration of letrozole after the oocyte pick-up can be useful to evaluate the benefit of this drug in patients with a tendency towards hyperresponse, in which both the discomfort after the stimulation and the risk of ovarian torsion are increased.

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

• To determine the levels of VEGF, VEGF/sFlt-1 ratio, LH, FSH, oestradiol, progesterone and testosterone in the plasma of oocyte donors depending on whether or not they receive the study treatment during the luteal phase. [Срок оценки: On the day of ovarian puncture, 5 days post-puncture and 10 days post-puncture.]
• To determine the duration of the luteal phase in oocyte donors depending on whether or not they receive the treatment under study during the luteal phase after ovarian stimulation. [Срок оценки: On the day of ovarian puncture and 10 days post-puncture.]