Fetal and neonatal alloimmune thrombocytopenia (FNAIT), a rare condition in which a mother’s immune system attacks her baby’s platelets, may be linked to maternal preeclampsia, according to a case report published recently in the American Journal of Perinatology Reports.
These results suggest that when a newborn shows signs of unexplained bruising or dangerously low platelet counts, doctors should consider FNAIT even if the mother has high blood pressure disorders during pregnancy.
This case described a male infant born at 40 weeks whose platelet count was only 7,000– far below the safe range. The newborn had widespread bruising, mouth spots and bleeding at an injection site within hours of delivery.
Despite an initial transfusion with random donor platelets, his platelet count barely rose. Only after receiving platelets carefully matched to avoid an immune reaction did his levels climb to 94,000 by the third day of life. By two weeks his platelets had risen to 218,000, and by three weeks after discharge, his platelets had risen to 290,000, both of which are within normal limits.
Read more about causes and risk factors of FNAIT
Testing revealed the baby had inherited a paternal platelet marker known as HPA-1a. His mother lacked this marker and developed antibodies against it, which crossed the placenta and destroyed her infant’s platelets. The placenta also showed evidence of low-grade chronic histiocytic intervillositis, a type of inflammation increasingly reported in FNAIT.
“This case is unique as it highlights a relationship between maternal alloimmunity and placental dysfunction and provides further support for a potential causal relationship between failed maternal immune tolerance and the development of preeclampsia,” explained the authors of this case study.
The mother, who had obesity and no prior pregnancies, developed severe preeclampsia during labor, requiring blood pressure medications and a cesarean delivery. Doctors suspect the same antibodies that damaged fetal platelets may also have attacked placental cells called extravillous trophoblasts, which regulate blood flow. This immune response could have triggered the mother’s late-onset preeclampsia, raising the possibility that in some cases preeclampsia is not a separate condition but a consequence of FNAIT.
For patients, the takeaway is twofold: first, infants with unexplained bruising or bleeding should be quickly tested and treated with platelet transfusions tailored to the antibody profile; second, parents should know that even in a first pregnancy, FNAIT can arise. In fact, studies show that most severe cases occur in first-time mothers.
When a newborn has severe thrombocytopenia, it is vital to check for maternal antibodies and send the placenta for pathology. With early diagnosis, targeted transfusions, and close follow-up, babies with FNAIT can recover fully, as in this case.
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