IRCT20160815029374N5 IRCT 2019-05-11 Mazandaran University of Medical Sciences PRP in infertility The effect of intrauterine infusion of platelet-rich plasma and number of infusion on increasing the thickness of endometrium and pregnancy rate in patients with thin endometrium. 2019-01-21 anticipated 20 Complete https://irct.ir/trial/29901 interventional Randomization: Randomized, Blinding: Not blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: Randomization is done based on the random number table on the day of estrogen initiation in freeze embryo transfer cycle by one nurse. In fact, only the nurse knows which patient is under the one or two PRP infusion. Physicians do not know which patient is undergoing one or two PRP, but patients know about the intervention due to informed consent,therefore, it is not possible to concealed the patients in this group. 2 Diseases of the genitourinary system. Intervention 1: Intervention group: Intrauterine infusion of 0.5 CC of autologus platelet-rich plasma (has 4-6 times platelet concentration rather than peripheral blood by IUI catheter(Takvin company, Iran) on day 11 of freeze embryo transfer cycle. Intervention 2: Intervention group: Intrauterine infusion of 0.5 CC of autologus platelet-rich plasma (has 4-6 times platelet concentration rather than peripheral blood by IUI catheter(Takvin company, Iran) on day 13 of freeze embryo transfer cycle. Intervention 3: Control group: Transfer of three Freeze embryos by chateter ( Cook, USA) under ultrasonographic guidance. Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is No more information