IRCT20160422027520N20 IRCT 2023-01-23 Tabriz University of Medical Sciences The effect of probiotics on fertility RIF The effect of probiotics on fertility in women with recurrent implantation failure based on Th1 to Th2 ratio 2023-02-20 anticipated 50 Complete https://irct.ir/trial/67981 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: At first, the sample size of 50 patients with RIF that met our inclusion criteria was considered as the total sample size. 'Random allocation rule' method was used for randomization, where numbers were randomly assigned to cards on a random order of one to 50. Even numbers were assigned to the treatment group and odd numbers to the control group (who did not receive any treatment). In this method, the balance will be reached at the end of the study in the number of people assigned to each group. Each card was placed in sealed and opaque envelopes to hide the random assignment, Blinding description: The participants and the person who analyzed the results were blinded in this study. Participants were aware of the study before being randomized and informed consent was obtained from them. It should be noted that the person analyzing the results had no other role in this study. 2 Recurrent implantation failure. Intervention 1: Intervention group: probiotic tablets (2 tablets per day) orally. Intervention 2: Control group: receive no intervention. 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 no more data