Oocyte retrieval will be performed 34-36 hours after hCG administration. Conventional IVF or intracytoplasmic sperm injection (ICSI) will be performed as appropriate. Embryos with 4-6 equally sized blastomers on day 2 with ≤ 20% fragmentation and no multinucleation will be considered top quality embryos. Embryos with 2-6 equally or unequally blastomers with ≤20% fragmentation and no multinucleation will be considered good quality embryos. Embryos will be transferred on day 2 or 3 under ultrasound guidance, with a C.C.D. embryo transfer catheter ( Laboratoire C.C.D., Paris, France). Luteal support with progesterone in oil (Progesterone, Aburaihan Co., Tehran, Iran) 100 mg daily IM will be started on the day of oocyte retrieval.