Received November 11, 2021
Accepted May 29, 2022

Objective: To investigate whether the timing of rLH addition to rFSH during controlled ovarian stimulation (COS) impacts ovarian response and the outcomes of intracytoplasmic sperm injection (ICSI) cycles. Methods: Data of 1278 patients undergoing ICSI between 2015 and 2018, in a private university–affiliated IVF center were analyzed. Patients were divided into groups according to the timing of LH addition to the COS protocol: Group LH-start (n=323), in which LH was administered since day 1 of ovarian stimulation; and Group LH-mid (n=955), in which LH was administered concomitantly with gonadotropin releasing hormone (GnRH) antagonist. Data were also stratified according to female age and response to COS. The outcomes of COS and ICSI were compared between the groups. Results: For the general group and in patients aged ≥ 35 years, higher blastocyst development rates were in Group LH-mid compared to Group LH-start. In patients with poor response to COS (POR), higher fertilization rate, blastocyst development rate and implantation rate were observed in Group LH-mid. Conclusion: rLH supplementation in POR patients may improve laboratorial and clinical outcomes when started in the mid-follicular phase, in GnRH antagonist ICSI cycles.