IRCT20200215046496N1 IRCT 2020-03-24 Tehran University of Medical Sciences Assessing the effect of supplemental injectable progesterone on complicated monochorionic diamnionic twin pregnanciy with radiofrequency ablation with cercival length of 25 mm or above on TVS Assessing the effect of supplemental injectable progesterone on complicated monochorionic diamnionic twin pregnanciy with radiofrequency ablation with cercival length of 25 mm or above on TVS 2019-03-17 anticipated 80 Complete https://irct.ir/trial/45842 interventional Randomization: Randomized, Blinding: Single blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: Simple randomization To the number of samples in each group, letters A or B were written on cards and put in a pocket. Prior to each intervention a card was taken out determining the patient allocation to case or control group, Blinding description: Follow up and result assessment of patients were performed by health care providers who were blind to allocation and the final results were available to the researcher and data analyzer by codes A and B. 3 complicated monochorionic diamnionic twin pregnancy. Intervention 1: Intervention group:  monochorionic twin pregnancies complicated with anomalous fetus or selective IUGR of a co-twin with cervical length more than 25 millimeters undergoing radiofrequency ablation, supplemental injectable progesterone in the form of 17hydroxyprogesterone caproate will be administered intramuscularly and the same dose will be injected weekly until 36 weeks gestation. the patients will be compared to the control group for whom , only the RFA is done and no further drug administration is performed. Intervention 2: . Intervention 3: Control group: monochorionic complicated twin pregnancies by anomalous fetus or selective IUGR and a cervical length more than 25mm, undergo ablation of the abnormal co-twin with radiofrequency and no supplemental progesterone and pregnancy outcome is followed.RFA is a single session procedure done through a needle using radiofrequency waves, resulting in occlusion of the abnormal co-twin cord and intrauterine fetal death while the other continue to grow. 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 discussing with colleagues