Neonatal Alloimmune Thrombocytopenia: A Report of Four Cases.

Antibodies against fetal platelet alloantigens in maternal blood cause neonatal alloimmune thrombocytopenia (NAIT). We encountered four newborns with NAIT from three women. A woman carried anti-human platelet antigen (HPA)-1a antibody, and vaginally delivered a newborn who had subarachnoid hemorrhage and platelet transfusions. She delivered the second newborn by a cesarean section who had no symptom. The second woman carried anti-human leukocyte antigen-A2 antibody and vaginally delivered a newborn who had no symptom. The third woman with a history of recurrent pregnancy losses carried anti-HPA-4b antibody, and delivered a newborn by a cesarean section who received platelet transfusions and immunoglobulin infusions. Antiplatelet antibody screening may be helpful in women who have a history of blood transfusion, or previous neonates with thrombocytopenia or intracranial hemorrhage.