The stimulation protocol will start on day 2 using 450-300 IU HMG ( Merional® IBSA, Lugano, Switzerland) and gonadotrophin releasing hormone antagonist, cetrorelix (Cetrotide® Merck Serono, Darmstadt, Germany) 0.025 mg daily. Gonadotropins will be administered for 4 to 5 days, after which the dose will be adjusted according to the ovarian response. The ovarian response will be monitored by transvaginal ultrasound and serum E2 levels. When three or more follicles reached a maximum diameter of 16 mm, highly purified HCG 5000 or 10,000 IU (Choriomon ®IBSA) will be administered. The procedure will be cancelled if less than 3 follicles 16 mm in size are present 12 days after starting gonadotropins despite doses reaching 450 IU. The cycle will be also cancelled if there is risk of ovarian hyperstimulation like massive ovarian enlargement or serum estradiol exceeds 3000pg/L Transvaginal oocyte retrieval will be performed 34-36 h after the administration of HCG. Oocytes will be fertilized either via IVF or ICSI based on the couple's history. Fertilization will be assessed 16-18 h after IVF or ICSI . Embryos will be transferred on Day 3 or 5. Vaginal tablets containing progesterone (Prontogest® IBSA) 400 mg/day will be given when fertilization is confirmed. A pregnancy test will be done 2 weeks after embryo transfer. For patients with a positive pregnancy test, progesterone is to be continued for an additional 4 weeks. Clinical pregnancy will be defined as Visualization of an intrauterine gestational sac 5 weeks after embryo transfer. And ongoing pregnancy will be defined as the sonographic confirmation of fetal heart pulsations at 12 weeks.