Overview
Fetal and neonatal alloimmune thrombocytopenia (FNAIT), also called neonatal alloimmune thrombocytopenia (NAIT or NAT), is a blood condition that affects babies before or shortly after birth. It happens when a mother's immune system makes antibodies against proteins on her baby's platelets — the tiny blood cells that help stop bleeding. This occurs because the baby inherits platelet proteins from the father that the mother does not have. Her immune system sees these proteins as foreign and attacks them, lowering the baby's platelet count to dangerously low levels. The most serious risk is bleeding, especially bleeding in the brain (intracranial hemorrhage), which can happen before birth or in the first days of life. Babies may be born with bruising, tiny red or purple spots on the skin called petechiae, or more serious internal bleeding. Some cases are mild, while others can be life-threatening or cause lasting brain injury. Treatment depends on how severe the condition is. Mothers in future pregnancies may receive intravenous immunoglobulin (IVIG) therapy to reduce antibody levels and protect the baby. Newborns with very low platelet counts may receive platelet transfusions. With careful monitoring and treatment, many babies do well, but early diagnosis is critical to prevent serious complications.
Key symptoms:
Unusually low platelet count in the newbornTiny red or purple pinpoint spots on the skin (petechiae)Bruising that appears easily or without clear causeBleeding from the belly button, circumcision site, or other woundsBleeding inside the brain (intracranial hemorrhage)Seizures in the newbornSwelling or bulging of the soft spot on the baby's headPale or yellowish skinUnusual sleepiness or difficulty waking the babyPoor feeding
Clinical phenotype terms (17)— hover any for plain English
Sporadic
Usually appears on its own, not inherited from a parent
Neonatal
Begins at or shortly after birth (first 4 weeks)
FDA & Trial Timeline
5 eventsJanssen Research & Development, LLC — PHASE3
Janssen Research & Development, LLC — PHASE3
Karolinska Institutet
Boston Children's Hospital
Boston Children's Hospital
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for Fetal and neonatal alloimmune thrombocytopenia.
3 clinical trialsare actively recruiting — trials can provide access to cutting-edge therapies.
View clinical trials →Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Fetal and neonatal alloimmune thrombocytopenia.
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Questions for your doctor
Bring these to your next appointment
- Q1.What platelet antigen mismatch caused this, and what does that mean for future pregnancies?,Should my partner and I be tested before we try to have another baby?,What is the risk that a future baby will be affected, and will it be more or less severe?,What monitoring and treatment would you recommend during my next pregnancy to protect the baby?,Does my baby need a brain scan, and what follow-up is needed if there was any bleeding?,Are there any activity restrictions or precautions while my baby's platelet count is still low?,Are there any clinical trials or research studies we should know about?
Common questions about Fetal and neonatal alloimmune thrombocytopenia
What is Fetal and neonatal alloimmune thrombocytopenia?
Fetal and neonatal alloimmune thrombocytopenia (FNAIT), also called neonatal alloimmune thrombocytopenia (NAIT or NAT), is a blood condition that affects babies before or shortly after birth. It happens when a mother's immune system makes antibodies against proteins on her baby's platelets — the tiny blood cells that help stop bleeding. This occurs because the baby inherits platelet proteins from the father that the mother does not have. Her immune system sees these proteins as foreign and attacks them, lowering the baby's platelet count to dangerously low levels. The most serious risk is ble
How is Fetal and neonatal alloimmune thrombocytopenia inherited?
Fetal and neonatal alloimmune thrombocytopenia follows a sporadic inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Fetal and neonatal alloimmune thrombocytopenia typically begin?
Typical onset of Fetal and neonatal alloimmune thrombocytopenia is neonatal. Age of onset can vary across affected individuals.
Are there clinical trials for Fetal and neonatal alloimmune thrombocytopenia?
Yes — 3 recruiting clinical trials are currently listed for Fetal and neonatal alloimmune thrombocytopenia on UniteRare. See the clinical trials section on this page for phase, sponsor, and site details sourced from ClinicalTrials.gov.
Which specialists treat Fetal and neonatal alloimmune thrombocytopenia?
23 specialists and care centers treating Fetal and neonatal alloimmune thrombocytopenia are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.