Neonatal and fetal alloimmune thrombocytopenia

Abstract

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is the result of maternal alloantibodies interaction with human platelets antigen. Maternal alloantibodies are generated following the contact of maternal immune system with paternally acquired antigens on the fetal human platelets (PLTs). HPA-1a alloantibodies are responsible for more than 80% of cases of FNAIT. Low prevalence of FNAIT that occurs in less than 1 case out of 1000 births, and even a lower risk for intracranial hemorrhage makes a controversial discussion whether a screening in pregnant patients would bring benefits. Concerning pathogenesis of FNAIT, it has been shown that fetal platelets caring HPA-1a antigen enters maternal circulation and produce an immune response, that leads to production of HPA-1a maternal antibodies that afterwards can pass the placenta causing fetal thrombocytopenia. The majority of mothers who gave birth to a newborn with FNAIT usually are asymptomatic, although they might have a previous affected pregnancy. Although management of pregnancies complicated by FNAIT is still in discuss and controversial, a systemic review studies in 2017 showed that best guidance and delivery for pregnancies that are at risk for FNAIT is a weekly maternal administration of intravenous immunoglobulin, adding glucocorticoids depending on severity of FNAIT.