IRCT20160722029027N10 IRCT 2022-03-14 Shahid Beheshti University of Medical Sciences the effect of sequential embryo transfer on pregnancy rate Comparison of the effect of sequential embryo transfer (at the stage of cleavage and blastocyst) with embryo transfer only at the blastocyct stage on pregnancy rate in patients with recurrent implantation failure 2020-11-21 anticipated 200 Complete https://irct.ir/trial/61501 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: Randomization will be done by generating random numbers in Excel software. 1. In a column of Excel we enter 100 samples in each group. 2. In the next column we generate random numbers using the following command: RAND () 3. After sorting the generated random numbers, a random list will be generated according to which people will be assigned to two groups, Blinding description: Blindness will be such that the patient will not know what treatment she will receive. Also, the researcher who records the results will not be aware of the type of treatment applied to the patient. 2 infertility. Intervention 1: Intervention group: In the two-stage embryo transfer group, one embryo is transferred in the cleavage stage on the third day and then on the 5th day, one embryo is transferred in the blastocyst stage. All embryos are transferred under ultrasound guidance using a soft catheter. Intervention 2: Control group: Both embryos, under ultrasound guidance using a soft catheter, are transferred to the blastocyst stage on day 5. Yes - There is a plan to make this available What will be shared: Only information about the main outcome can be shared. When: Without restriction To whom: All researchers Conditions: With permission from the responsible author Where to obtain: With permission from the responsible author How to obtain: Email to the responsible author Comments: