The investigators are undertaking a multicenter, open-labeled, pilot study of 50 ITP patients in pregnancy from Peking University People's Hospital and other well-known hospitals in China. ITP patients in pregnancy who failed to respond to prednisone, IVIG and developed refractoriness to platelet transfusion will be given dexamethasone intravenously at a dose of 40mg every day for four days. Platelet count, bleeding and other symptoms will be evaluated before and after treatment. Adverse events will be recorded throughout the study.