A study recently published in Transfusion has identified several factors associated with severe neonatal thrombocytopeniaNeonatal thrombocytopenia Low platelet count in a newborn. In FNAIT, platelet levels may drop dangerously low within hours after birth. in pregnancies affected by fetal and neonatal alloimmune thrombocytopeniaFetal and neonatal alloimmune thrombocytopenia A rare condition in which a mother’s immune system attacks fetal platelets, leading to dangerously low platelet levels before and/or after birth. (FNAITFetal and neonatal alloimmune thrombocytopenia A rare condition in which a mother’s immune system attacks fetal platelets, leading to dangerously low platelet levels before and/or after birth.).
Researchers conducted a retrospective study of 71 patients and 119 pregnancies managed between 1993 and 2022. They compared pregnancies that resulted in severe neonatal thrombocytopenia (defined as a platelet countPlatelet count A measure of how many platelets are in the blood. FNAIT is characterized by severely reduced counts in a fetus or newborn. below 50,000/mm³ or the presence of fetal or neonatal intracranial hemorrhageBrain bleed Bleeding inside the fetal brain, also known as an intracranial hemorrhage. In FNAIT, it's often caused by severe thrombocytopenia and can lead to long-term disability or death. ) with pregnancies in which newborns had normal or only moderately reduced platelet counts.
The analysis found that a history of severe thrombocytopeniaSevere thrombocytopenia A dangerously low platelet count, typically below 50,000 platelets per microliter and sometimes far lower in FNAIT. in a previous affected pregnancy was strongly associated with severe disease in subsequent pregnancies. Every mother whose infant developed severe thrombocytopenia had experienced a prior pregnancy complicated by severe neonatal thrombocytopenia, compared with about three-quarters of mothers whose infants had milder disease.
Researchers also found that severe cases were more likely to involve antibodies targeting the human platelet antigenHuman platelet antigen Proteins found on the surface of platelets. Incompatibility between maternal and fetal human platelet antigens can trigger FNAIT. HPAHuman platelet antigen Proteins found on the surface of platelets. Incompatibility between maternal and fetal human platelet antigens can trigger FNAIT.-1a system, which has previously been linked to more serious forms of FNAIT.
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In addition, women whose babies developed severe thrombocytopenia were significantly less likely to have received treatment with intravenous immunoglobulinIntravenous immunoglobulin A treatment given to pregnant women with a history of FNAIT or known alloantibodies. IVIG reduces the immune reaction against fetal platelets. (IVIGIntravenous immunoglobulin A treatment given to pregnant women with a history of FNAIT or known alloantibodies. IVIG reduces the immune reaction against fetal platelets.) during pregnancy. IVIG is commonly used in pregnancies considered at high risk for recurrent FNAIT because it can help reduce the destruction of fetal platelets.
The researchers noted that identifying women at highest risk is critical because severe FNAIT can lead to serious bleeding complications, fetal or neonatal death and long-term neurological injuries. They concluded that a woman’s obstetric history should play a central role in risk assessment and treatment planning for future pregnancies.
“FNAIT must be identified and appropriately managed to limit its potentially dramatic consequences, including fetal/neonatal death,” the researchers wrote. “Based on the patient’s history, risk stratification for the occurrence of severe FNAIT in future pregnancies should be performed to tailor its management accordingly.”
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