Does Daily Co-Administration of Gonadotropins and Letrozole during the Ovarian Stimulation Improve IVF Outcome for...

Address and identify the sub-group of patients that might benefit from letrozole co-treatment throughout the entire ovarian stimulation (OS).

A retrospective cohort study.

Patients who underwent two successive IVF cycle attempts, where the 2nd included the co-administration of 5 mg Letrozole from OS day 1 until trigger day.

IVF institute of a tertiary medical center.

First and second cycle attemtps were compared with regard to cycle characteristics and results. Different subroups according to ovarian response were considered.

Two hundred patients met the inclusion criteria and were included in the study. Of whom, 65 were poor responders (oocytes ≤3) during the first IVF cycle attempt, 85 were sub-optimal responders (4-9 oocytes), and 50 were normal responders (≥10 oocytes). The total dose of gonadotropins (4,525 ± 1,553 vs. 4,293 ± 2,166, p = NS) and length of stimulation (11.3 ± 2.2 vs. 11.1 ± 2.3, p = NS) were comparable between the two cycle attempts. Numbers of follicles ≥13 mm (7.2 ± 4.7 vs. 6.2 ± 4.3, p < 0.001), retrieved oocytes (8.6 ± 6.1 vs. 6.9 ± 5.5, p < 0.001), zygotes (5.7 ± 4.5 vs. 4.5 ± 3.7, p < 0.001) and number of top quality embryos (TQE) (2.5 ± 2.5 vs. 1.8 ± 1.9, p < 0.001) were significantly higher in letrozole cycles. Sub-analysis according to patients' ovarian response during the first attempt revealed that the poor and sub-optimal responders significantly benefit from the letrozole co-administration, while the normal responders did not.

Letrozole co-administration during OS for IVF increases the number of retrieved oocytes, zygotes, and TQE in poor and sub-optimal responders but not in normal responders.