IRCT20210216050385N1 IRCT 2021-11-13 Dezfoul University of Medical Sciences effect of sildenafil citrat on endometrial thickness Comparative effect of oral and vaginal sildenafil on endometrial thickness in infertile women with thin endometrium in frozen embryo transfer cycles 2022-03-21 anticipated 72 Complete https://irct.ir/trial/54414 interventional Randomization: N/A, Blinding: Double blinded, Placebo: Not used, Assignment: Single, Purpose: Treatment, Blinding description: In this double-blind study, sick people, ie infertile women, will be unaware of how the study groups are divided into two groups receiving placebo and the main drug, and also those who will perform the intervention in the clinic, ie researchers will be unaware from the distribution of study groups receiving placebo and The main drug. N/A infertility. Intervention 1: Intervention groupe 1:The second group, in addition to the estradiol treatment protocol, will be given oral sildenafil citrate tablets. Then, in the next stage of progesterone injection, 100 mg intramuscular for three to four days. Intervention 2: Intervention groupe 2: In the third group, in addition to the estradiol treatment protocol, sildenafil citrate tablets will be given to the vagina. Due to the unavailability of vaginal sildenafil, the patient is asked to moisten the oral sildenafil citrate tablet and place it in the vagina. 100 mg intramuscular for four days. Intervention 3: Control groupe 1: The first group will receives only oral estradiol 3 times a day and then in the next stage of progesterone injection for three to four days at a rate of 100 mg intramuscular. 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 There is not more information