IRCT20150310021420N4 IRCT 2018-07-13 Tehran University of Medical Sciences The effect of letrozole on treatment of endometriosis-related infertility Evaluation of the effect of letrozole addition to GnRH-antagonist protocol on IVF/ICSI cycle outcome in women with endometriosis 2018-05-22 anticipated 144 Complete https://irct.ir/trial/31976 interventional Randomization: Randomized, Blinding: Not blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: According to Stratified Block randomization, the samples will be divided into two groups of intervention and control (based on the PCOS variable), the number of blocks will be 6. The random allocation list is solely available to the epidemiologist. For Concealment of the random allocation process, treatments will be written on 144 cards, respectively. then the cards are placed inside sealed envelopes. When the physician announces the eligibility of a patient, the methodologist will provide the physician with the envelope. N/A endometriosis-related infertility. Intervention 1: Intervention group: Adding letrozole at a dose of 2.5 mg per day from the third day of the cycle to the antagonist treatment cycle for 5 days. Intervention 2: Control group: Antagonist protocol without placebo. 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 The research team has not yet made a decision on how to publish the results or the statistical analysis map.