IRCT201205131141N12 IRCT 2012-07-13 Royan Institute The effect of low dose Aspirin in increasing the chance of pregnancy To evaluate the effect of low dose Aspirin in increasing the chance of pregnancy in frozen embryo transfer cycles 2012-05-01 anticipated 60 Complete https://irct.ir/trial/205 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment, Other design features: The patients will be followed until 20 weeks of gestation and the results of treatment cycle will be compared in two groups. Data analysis will be performed by means of SPSS software program. 3 Infertility. Intervention 1: With the onset of endometrial preparation and estrogen treatment, the study group will receive 100 mg of oral aspirin. Intervention 2: With the onset of endometrial preparation and estrogen treatment, the control group will receive placebo.