Parallel randomized trials of risk-based therapy for fetal alloimmune thrombocytopenia

OBJECTIVE: Antenatal therapy with intravenous immunoglobulin (IVIG) and prednisone has been shown to improve fetal thrombocytopenia and reduce the incidence of intracranial hemorrhage in neonatal alloimmune thrombocytopenia. Optimization of this therapy for individual patients, however, has yet to be achieved. METHODS: In these parallel, randomized, multicenter studies, 78 patients in 79 pregnancies were stratified to 2 different treatment arms based on the presence of a peripartum intracranial hemorrhage in a previously affected sibling and/or the initial fetal platelet count. Patients with a history of an antenatal intracranial hemorrhage in a prior pregnancy were excluded. RESULTS: Forty women whose children from a previous birth had a peripartum intracranial hemorrhage or whose current fetus had an initial platelet count less than 20,000/mL(3) were randomly assigned to receive IVIG plus prednisone or IVIG alone. The mean increase in fetal platelet counts in the following 3 to 8 weeks was 67,100/ mL(3) and 17,300/mL(3), respectively (P < .001). Thirty-nine patients whose prior affected child did not have an intracranial hemorrhage and whose initial platelet count was more than 20,000/mL' were randomly assigned to receive IVIG alone or prednisone alone. There were no significant differences, and 33 (85%) had birth platelet counts more than 50,000/mL(3). There were 11 (6%) significant complications after a total of 175 fetal blood sampling procedures, 2 of which led to fetal or neonatal deaths. CONCLUSION: The spectrum of disease severity of alloimmune thrombocytopenia is reflected in the initial fetal platelet count and response to therapy. Fetal blood sampling may be associated with significant fetal/neonatal morbidity and mortality. Empiric therapy sufficient to treat the most severely affected fetuses will overtreat others and is likely to be associated with additional maternal morbidity.