IRCT20151013024512N6 IRCT 2020-02-29 Vice chancellor for research,Shahid Sadoughi university of medical science, Yazd ,Iran uterus preparation with letrozol for polycystic patients in frozen embryo transfer cycle Endometrial preparation with letrozol in frozen embryo transfer cycle in woman with pco syndrom 2020-01-20 anticipated 180 Complete https://irct.ir/trial/46112 interventional Randomization: Not randomized, Blinding: Not blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment. 3 female infertility. Intervention 1: Intervention group :Infertile 20-40 yr PCO candidate for frozen thawed embryo transfer will get 5mg letrozol from day 3 to 7 of cycle and vaginal sonography will be done on day 10.If we have 14mm or more dominant follicle ,vaginal sonography will be done every other day till reaching to 17mm follicle and 7-9 mm endometrium.if we don't have dominant follicle on day 10 ,75 mg daily HMG will be add to letrozol and follow up sonography will be done till reaching to our golds.after reaching to dominant follicle 10000 unit HCG will be prescribe at 10 pm and 400 mg daily progesterone will be prescribe after 2 days and after 5 days of injecting HCG ,embryo transferring will be done. Intervention 2: Control group: Infertile 20-40 yr PCO candidate for frozen thawed embryo transfer will get 6mg estradiol from second day of cycle and serial vaginal sonography will be done from 12th day of cycle when thickness reaches 7mm or more, they receive 400 mg progesterone for 3 days and then embryo transfer will be done. No - There is not a plan to make this available Justification or reason for not sharing IPD is No more information exist