Preventing brain hemorrhage in newborns affected by fetal and neonatal alloimmune thrombocytopenia (FNAIT) is now more precise and less invasive than ever before, according to expert reviews of current clinical practices published recently in Best Practice and Research Clinical Obstetrics and Gynaecology.
FNAIT, a rare immune disorder affecting about one in 1,000 pregnancies, occurs when the mother’s immune system attacks the fetus’s platelets, potentially leading to severe thrombocytopenia and intracranial hemorrhage. These bleeds often happen before birth and can cause permanent neurological damage or death if untreated.
Most pregnancies complicated by FNAIT are not identified until after birth, as screening for the platelet antigen HPA-1a, which is the most common cause, is not routine. The disorder is typically discovered when a newborn develops widespread bruising or pinpoint red spots (petechiae) soon after delivery. Laboratory tests can confirm the diagnosis by identifying incompatible platelet antigens between mother and baby and detecting maternal antibodies that target fetal platelets.
“[W]ithout the implementation of antenatal screening to identify HPA-1a negative pregnant women, there is limited utility of prophylaxis and upcoming improved therapeutic treatments,” explained the review’s authors. They continued, “To address this gap and enable more targeted treatment strategies for this rare disease, large scale data are needed.”
Read more about treatment and care for FNAIT
For women who have had one affected child, the next pregnancy carries the highest risk. In these cases, preventive treatment with high-dose intravenous immunoglobulin, sometimes paired with corticosteroids, is given weekly beginning around 20 to 24 weeks of pregnancy.
Although intravenous immunoglobulin remains the cornerstone of FNAIT prevention, it is expensive, time-consuming, and not without side effects. Some countries, including Norway and the Netherlands, reserve treatment for pregnancies at the highest risk of intracranial hemorrhage, while others take a broader approach.
Invasive procedures once used to monitor or treat FNAIT, such as fetal blood sampling and intrauterine platelet transfusion, are now largely avoided because they can worsen bleeding or cause fetal death. Instead, noninvasive monitoring, including ultrasound and MRI, helps detect hemorrhage or growth restriction. New biomarkers linked to placental health, such as sFlt-1 and placental growth factor, show promise for predicting which pregnancies are most at risk.
For patients, these advances mean safer pregnancies, fewer invasive interventions, and more individualized care. However, because FNAIT remains underdiagnosed and often appears without warning, experts continue to call for broader awareness and further research to refine treatment timing and improve outcomes for mothers and babies alike.
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