A pregnancy following a case of fetal and neonatal alloimune thrombocytopenia (FNAIT) is generally thought to present with more severe disease. However, in one case report published in Case Reports in Pediatrics, the second child had milder manifestations than the first after the mother received standard treatment.
The first case was of a female newborn delivered at 39 weeks and three days of gestation. Although the delivery was uncomplicated, she had petechiae (small red spots caused by bleeding under the skin) over her body. Doctors then ordered blood tests and found severe thrombocytopeniaSevere thrombocytopenia A dangerously low platelet count, typically below 50,000 platelets per microliter and sometimes far lower in FNAIT., with 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. of 3,000/mm3, two hours after birth. Normal platelet counts are above 150,000/mm3.
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The baby was transferred to the NICUNeonatal intensive care unit A specialized hospital unit for newborns who need close monitoring and treatments such as platelet transfusions. and received platelet transfusions and an 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.) infusion. IVIG contains antibodies from healthy donors that help reduce the destruction of the baby’s platelets caused by maternal antibodies. Doctors also performed a head ultrasound, which showed no signs of intracranial bleeding. Her platelet counts gradually improved, and she was discharged after six days.
Testing of both parents showed that they carried different versions of a platelet antigen. Because of this mismatch, the mother’s immune system recognized the baby’s platelets as foreign and produced antibodies against them.
Learn more about FNAIT signs and symptoms
Seventeen months later, the mother became pregnant again. As she had a history of FNAIT, doctors started treatment during pregnancy with weekly IVIG and daily prednisone at 20 weeks.
The second baby was delivered by cesarean section at 37 weeks and 5 days. His platelet count was 24,000/mm3 at birth, still considered severe thrombocytopenia, but much higher than his sister’s count of 3,000/mm3. Unlike his sister, he did not have petechiae or other signs of bleeding.
The authors noted that “retrospective studies generally suggest that subsequent pregnancies tend to be more severely affected than the initial one.” In contrast, the second child in this case had a milder presentation and faster recovery, which the authors suggested may have been related to antenatal treatment with IVIG and prednisone.
