Tehran University of Medical Sciences Journal of Family and Reproductive Health 1735-8949 9 1 2015 03 15 1 4 Elham Azimi Nekoo Tehran University of Medical Sciences, Tehran, Iran. Maryam Chamani Tehran University of Medical Sciences, Tehran, Iran. Ensieh Shahrokh Tehrani Reproductive Health Research Center, Tehran University of Medical Sciences, Tehran, Iran. Batool Hossein Rashidi Reproductive Health Research Center, Tehran University of Medical Sciences, Tehran, Iran. Fatemeh Davari Tanha Women's hospital, Tehran University of Medical Sciences, Tehran, Iran. Vahid Kalantari St Maarten School of Medicine, American University of Integrative Sciences, Cole Bay, St. Maarten. 2015 10 16 Objective: To investigate the reproductive outcome of artificial endometrial preparation with exogenous steroids for frozen-thawed embryo transfer with and without pre-treatment with depot gonadotropin releasing hormone agonist (GnRH-a) in women with regular menses. AMaterials and methods:This is a prospective randomized clinical trial conducted in two RT centers on 176 women undergoing frozen-thawed embryo transfer. All patients received oral estradiol valerate 4 mg daily from day 2 to day 5 and 6 mg per day from day 6 to the day of the pregnancy test. In day 13 of cycle, an ultrasound examination was performed. After ultrasound confirmation of endometrial thickness (≥8 mm) and no ovarian activity, progesterone in cyclogest supp (800 mg daily) was added. The dose of estradiol would be increased to 8 mg per day if the endometrial thickness was less than 8mm. Two or 3 embryos were transferred via transcervical route 48 hours after the beginning of progesterone administration. In group A (93 patients), Difereline (3.75 mg Im), as a depot GnRH agonist was administered in the midluteal phase (day 21) of previous cycle. In the other group B (n = 83) steroid supplementation was commenced without prior pituitary suppression. Chemical and clinical pregnancy rates were compared in two groups. Results:No significant differences were seen between two groups in terms of chemical pregnancy and clinical pregnancy rates. Conclusion:The findings support the artificial protocol without any pretreatment suppressive drugs to reduce the adverse side effects of GnRH agonists also to minimize the costs. https://jfrh.tums.ac.ir/index.php/jfrh/article/view/221 https://jfrh.tums.ac.ir/index.php/jfrh/article/download/221/216