IRCT2016031022795N3 IRCT 2016-04-03 Tehran University of Medical Sciences Comparison of fertility outcome in freeze embryo transfer cycles with endometrial preparation by natural cycle or artificial cycle The comparison of fertility outcome obtained from freeze embryo transfer in natural cycle and estrogen progestrone cycle for endometrial preparation 2015-09-23 anticipated 140 Complete https://irct.ir/trial/19587 interventional Randomization: Randomized, Blinding: Not blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment. N/A Infertility. Intervention 1: In the natural cycle group patients will be followed with several sonography for seeing dominant follicle more than 18 mm and then 10000 IU HCG will be administrated and 4 days later the embryos will be transferred. Intervention 2: On the artificial group in the months before starting the transfer cycle from 21 days of luteal phase GnRh agonist (busereline Merck) at a dose of 0.5mg (500mgr) daily will be started.Then on the 2th day of the next cycle estradiol valerate 2mg daily will be started and to 8mg will be adjusted based on the endometrial thickening.on the 10-12th cycle day TVS for evaluation endometr will be done and if ET>9 mm was observed SUPP progestrone (cyclogest 400mg/BD) will be added for 3 days at the same time .The embryo transfer will be scheduled at 72 hours after starting progestrone.