New perspectives on fetal and neonatal alloimmune thrombocytopenia for obstetricians

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a serious disorder that arises when a mother produces alloantibodies against specific human platelet antigens (HPAs) expressed on fetal platelets. These maternal alloantibodies cross the placenta and destroy fetal platelets, significantly increasing the risk of fetal or neonatal intracranial hemorrhage (ICH). Indeed, FNAIT is the leading cause of isolated severe thrombocytopenia in otherwise healthy neonates. In this review, we summarize recent advances to provide obstetricians and maternal-fetal medicine specialists with an updated overview of FNAIT, encompassing its pathophysiology, clinical features, diagnostic strategies, antenatal management, delivery planning, and postnatal care. Although the prophylactic interventions remain at an early stage, HPA histo-incompatibility prescreening is already available at a suitable cost, and the development of NAITgam, a targeted immunoglobulin preparation, represents a promising advance. While the widespread implementation of screening and prophylaxis may take years, such measures have the potential to significantly reduce the incidence and severity of FNAIT. Currently, the antenatal administration of intravenous immunoglobulin (IVIg), with or without corticosteroids, remains the safest and most effective treatment for high-risk pregnancies. Looking ahead, animal model data continue to provide valuable insights that may inform the development of novel preventive and therapeutic strategies. Ultimately, the implementation of a national screening program could prevent severe complications and help mitigate the long-term societal and healthcare burden of FNAIT.