ABSTRACT
OBJECTIVES: To investigate whether adding letrozole in the early follicular phase of a gonadotropin-releasing hormone (GnRH) antagonist (GA) stimulation cycle improves in vitro fertilization (IVF) outcomes in poor responder patients. MATERIAL AND METHODS: To be included in this study, patients had to have had at least one previous GA cycle and a subsequent GA cycle with added early follicular phase letrozole (LzGA). A total of 41 poor responder patients were identified based on the Bologna criteria. RESULTS: The LzGA group had a lower dosage of follicular stimulating hormone (FSH) (p = 0.001), the duration of stimulation days (p = 0.015) and the duration of GnRH antagonist stimulation days (p = 0.033) when compared with controls. Comprehensive analysis of the cycle characteristics showed that the number of oocytes retrieved, the number of MII oocytes retrieved, the number of fertilized oocytes, and the fertilization rate were significantly higher in the LzGA cycle (p = 0.041, p = 0.019, p = 0.008, p = 0.01, respectively). The rate of cycle cancellation was lower in the LzGA group (24.4%) than in the GA group (48.8%), (p < 0.001). Although LzGA administration demonstrated a trend toward improved implantation and clinical pregnancy rates, this was an insignificant trend (p = 1.000, p = 0.177, respectively). CONCLUSIONS: Adjunctive letrozole administration seems to restore an IVF cycle by improving the cycle characteristics and reducing the total gonadotrophin dosage.