Fetal and neonatal alloimmune thrombocytopenia (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.) can cause severe platelet loss and potentially life-threatening bleeding, but early recognition and treatment can help prevent serious complications, according to a case report published recently in Cureus.
This recent case involving a preterm newborn demonstrated how antenatal 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.), careful monitoring and prompt neonatal treatment can support a favorable outcome, despite severe thrombocytopeniaSevere thrombocytopenia A dangerously low platelet count, typically below 50,000 platelets per microliter and sometimes far lower in FNAIT..
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“Collectively, current evidence supports antenatal IVIG as preventive therapy but indicates that postnatal IVIG does not confer additional benefit over platelet transfusionPlatelet transfusion A treatment for newborns with very low platelet counts that ideally uses HPA-compatible or washed maternal platelets. alone in terms of platelet increment or bleeding prevention, and its routine use in stable neonates remains unsupported by high-quality data,” the authors wrote.
The baby boy was born at 35 weeks, earlier than the usual 40-week pregnancy, by vaginal delivery. He weighed 2,235 grams at birth and had Apgar scores of 8 at one minute and 9 at five minutes, indicating that he was doing well immediately after birth.
However, doctors knew he was at higher risk for FNAIT because an older sibling had developed severe FNAIT at 36 weeks. The mother was healthy, had normal platelet levels throughout pregnancy and had no history of autoimmune disease.
Testing showed that the mother had a specific platelet type called HPAHuman platelet antigen Proteins found on the surface of platelets. Incompatibility between maternal and fetal human platelet antigens can trigger FNAIT.-1b and had antibodies against platelet proteins that could affect the baby. To reduce the risk of complications, she began weekly treatment with IVIG at 16 weeks of pregnancy. She received 1 g/kg with each treatment. She also received corticosteroids near delivery to help the baby’s lungs mature. Regular ultrasound scans during pregnancy showed no signs of bleeding in the baby’s brain.
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The baby’s 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. was already low at birth, at 37 × 10⁹/L, and dropped further to 25 × 10⁹/L on the third day of life. Despite the low platelet count, he looked healthy and had no bruising, small red or purple spots on the skin or other signs of bleeding. An ultrasound of his brain also showed no bleeding. He received platelet transfusions on days 3 and 4. Because his platelet count did not increase enough after the transfusions, he received 2 doses of IVIG at 1 g/kg on day 5. His platelet count then increased to 234 × 10⁹/L by day 8.
The baby was discharged from the hospital on day 8 and continued to do well. His platelet count rose to 388 × 10⁹/L at the first follow-up visit one week later and to 450 × 10⁹/L at a second visit one week after that. Additional testing confirmed that the mother’s antibodies were reacting against platelet proteins inherited from the father, confirming the diagnosis of FNAIT.
For patients and families, the case underscores the importance of identifying a previous affected pregnancy because FNAIT can recur and fetal bleeding may occur before birth. FNAIT is estimated to affect about 1 in 1,000 to 3,000 live births, but its frequency in the Middle East, where this case occurred, is uncertain. HPA patterns vary among populations and may affect both disease risk and access to compatible platelets. Better regional awareness, organized screening and availability of HPA-typed platelet products could help families receive timely diagnosis and treatment.
