Mild cases of fetal and neonatal alloimmune thrombocytopenia (FNAIT) are often described as self-limiting and transient. In such cases, symptoms progressively disappear in two to four weeks following birth, often with no long-term consequences.
More severe cases of FNAIT are less common and may involve gastrointestinal or intracranial hemorrhages in the newborn that require immediate treatment until symptoms are resolved. Cases of FNAIT identified during pregnancy require monitoring and treatment to prevent the most severe outcomes.
Can FNAIT go away on its own during pregnancy?
FNAIT occurs when maternal antibodies attack the fetal platelets during pregnancy, gradually breaking them down. This causes thrombocytopenia or a low fetal platelet count, which causes the blood to lose its ability to clot. In severe cases, the result is uncontrolled bleeding and hemorrhage. In the majority of cases, FNAIT is only detected following delivery, as a result of visible symptoms such as bruising, petechiae, purpura and a low blood platelet count.
There is no standard prenatal screening for FNAIT, so diagnosis during pregnancy is made based on fetal symptoms. Close monitoring will detect any evolution in symptoms and risk to the fetus. Prenatal FNAIT requires treatment to prevent or delay the onset of severe thrombocytopenia, which may lead to intracranial hemorrhage, the most dangerous of FNAIT complications.
Early delivery is often necessary to remove the fetus from the ongoing toxic effects of the maternal antibodies and to allow for urgent platelet transfusions to boost platelet levels and reduce the symptom burden.
Untreated prenatal FNAIT can lead to severe fetal outcomes, including permanent neurological damage and even fetal death.
Why does FNAIT sometimes resolve without treatment?
When a baby is delivered, it is removed from the impact of maternal antibodies that attack platelets. As the antibodies already present in the newborn decline over time, platelet levels gradually increase and mild associated symptoms such as bruising start to ease.
Mild cases of FNAIT that are identified post-delivery may have only developed in the later stages of pregnancy or during delivery. This leaves a smaller window of time for the production of maternal antibodies and less time for the antibodies to cross the placenta and attack the baby’s platelets. These cases are more likely to resolve on their own, without treatment.
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