Ovarian stimulation was performed using GnRH antagonist protocol. All matured oocytes were inseminated by ICSI. Injected oocytes were cultured in medium supplemented with 2ng/ml of GM-CSF (Embryogen, Origio) until day of transfer. Embryo evaluation was performed at ﬁxed time points of 18 and 44 hour after fertilization. Embryo transfer was performed 2 days after ovum retrieval.