Effectiveness of the antagonist/letrozole protocol for treating poor responders undergoing in vitro fertilization/intracytoplasmic sperm injection: a systematic review and meta-analysis.

In view of the conflicting data regarding the efficacy of the gonadotropin-releasing hormone (GnRH) antagonist/letrozole (A/L) protocol for treating poor responders undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI), this systematic review and meta-analysis aimed to compare the effectiveness of the A/L protocol and the microdose GnRH agonist flare up (MF) protocol for such treatment. MEDLINE, EMBASE, Web of Science, and the China National Knowledge Infrastructure were searched for studies comparing the A/L and MF protocols for treating poor responders undergoing IVF/ICSI. We retrieved reports of three trials with data for 688 cycles in women. The clinical pregnancy rate was significantly decreased with the A/L compared with MF protocol (RR 0.70; 95% CI: 0.57-0.86; p = 0.001), the duration of gonadotrophin stimulation was lower with the A/L than MF protocol (MD -1.25; 95% CI: -2.37 to -0.12; p = 0.03). Moreover, there was no significant difference in cycle cancellation rate, number of oocytes retrieved, and the total dose of gonadotrophin between the two protocols. In conclusions, the clinical pregnancy rate may be lower with the A/L than MF protocol for treating poor responsers undergoing IVF/ICSI, but large-scale randomised controlled trials are needed to assess the A/L protocol.