Neonatal alloimmune thrombocytopenia in consecutive pregnancies.

Neonatal and antenatal alloimmune thrombocytopenia is caused by the placental passage of maternal antibodies directed against platelet-specific fetal antigens. This disease is analogous to Rhesus hemolytic disease of the newborn and may be complicated by intracranial hemorrhage. Following increased awareness to the disease, it is currently no longer considered to be rare. Recent advances in the utilization of percutaneous umbilical cord blood sampling has led to a dramatic change in both prenatal and intranatal management of affected fetuses. We present a sibship with four infants, three of them found to have alloimmune thrombocytopenia. The neonatal thrombocytopenia in the subsequent births was not shown to be more severe, as could have been expected from the pathophysiologically analogous Rh hemolytic disease of the newborn. The role of prenatal determination of platelet count, intrauterine treatment with immunoglobulins and platelet transfusions, and elective cesarean section, in preventing possible hemorrhagic complications in repeated pregnancies should be reconsidered, taking into account the natural history of this rare disorder.