This is a prospective, randomized, open-label, multicenter clinical trial study to compare the efficacy and safety of prednisone plus IVIg to prednisone monotherapy in the treatment of immune thrombocytopenia (ITP) in pregnancy.

The investigators are undertaking a prospective, parallel group, multicenter, randomized controlled trial in pregnant patients with treat-naive ITP. A total of 100 participants are randomized to two groups with the 1:1 ratio: prednisone plus IVIg group versus prednisone monotherapy group. Participants will receive prednisone 20mg per day for 4 weeks plus IVIg 400mg/Kg (total dose ≤20g per day) for 5 days or prednisone 20mg monotherapy per day for 4 weeks. Platelet count, bleeding and other symptoms were evaluated before and after treatment. Time to response and platelet counts of newborns are investigated. Adverse events including participants and their newborns are also recorded throughout and after the study.

Inclusion Criteria:

1. Age 18-50 years old;
2. Meet the diagnostic criteria for immune thrombocytopenia;
3. Pregnant women with ITP without ITP-specific treatments during pregnancy;
4. Gestational weeks ≥12 weeks;
5. Platelet count <30×10^9/L, accompanied with or without bleeding symptoms.
6. Willing and able to sign written informed consent.

Exclusion Criteria:

1. Have a known diagnosis of other autoimmune diseases, confirmed medical history or laboratory findings within positive anti-nuclear antibodies (>1:80), anti-cardiolipin antibodies, lupus anticoagulant factors or direct Coombs' test.
2. Thrombocytopenia caused by pregnancy-specific conditions, such as gestational thrombocytopenia, preeclampsia, the HELLP syndrome and acute fatty liver of pregnancy.
3. Secondary thrombocytopenia such as drug-related thrombocytopenia, vaccine-related thrombocytopenia, lymphoproliferative disorders, severe infection, hepatic cirrhosis and so on.
4. With other underlying diseases that may cause thrombocytopenia, such as: malignant disease, megaloblastic anemia, aplastic anemia, myelodysplasia syndrome, myeloid fibrosis, disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, Hemolytic uremic syndrome, disseminated intravascular coagulation and so on;
5. Current HIV infection or hepatitis B virus or hepatitis C virus infections;
6. With severe heart, kidney, liver or respiratory dysfunction;
7. With the medical history of mental illness;
8. Have allergic reaction to prednisone or IVIg;