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Fetal and neonatal alloimmune thrombocytopenia


Other Names:
NAIT
Categories:
Fetal and neonatal alloimmune thrombocytopenia (NAIT) is a blood disorder that affects pregnant women and their babies.[1] NAIT was first reported in the literature in 1953 and is estimated to occur in as many as 1 in 1200 live births.[2] NAIT results in the destruction of platelets in the fetus or infant due to a mismatch between the mother’s platelets and those of the baby. Certain molecules (antigens) on the surface of the baby's platelets are recognized as foreign by the mother's immune system. The mother’s immune system then creates antibodies that attack and destroy the baby’s platelets.[1][2][3][4] Though NAIT can occur whenever the mother’s blood mixes with that of the baby, it is usually triggered when the mother is exposed to the baby’s blood during delivery. Many cases of NAIT are mild. Signs and symptoms may include a low platelet count (thrombocytopenia) and signs of bleeding into the skin such as petechiae and purpura. In the most severe cases, NAIT can cause bleeding episodes that may result in death or long-term disability. Bleeding episodes can occur either during pregnancy or after birth.[3] Management of the infant with neonatal alloimmune thrombocytopenia may include platelet transfusions, ultrasounds, and intravenous immunoglobulin (IVIG). Treatment for pregnant mothers at risk for NAIT may include IVIG and steroids.[3] 
Last updated: 10/9/2017
Some cases of NAIT are mild.[2] The most common sign is bleeding into the skin which may present as petechiae or localized swellings (hematomas). In more severe cases, the infant may experience bleeding episodes affecting the brain or major organs. These bleeding episodes can be life-threatening.[3] 
Last updated: 10/9/2017

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
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HPO ID
100% of people have these symptoms
Neonatal alloimmune thrombocytopenia 0004809
30%-79% of people have these symptoms
Cephalohematoma 0012541
Petechiae 0000967
Spontaneous hematomas 0007420
5%-29% of people have these symptoms
Ecchymosis 0031364
Hematuria
Blood in urine
0000790
Melena 0002249
1%-4% of people have these symptoms
Bilateral sensorineural hearing impairment 0008619
Blindness 0000618
Cerebral palsy 0100021
Global developmental delay 0001263
Subarachnoid hemorrhage 0002138
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Last updated: 7/1/2020
As there is no universal screening test for NAIT, the first case of NAIT in a family is often unexpected.[2][4] However, there is a high recurrence risk for NAIT and consultation with a maternal-fetal medicine specialist or other professional with experience treating NAIT is indicated in future pregnancies once a diagnosis of NAIT is made.[2][3] Blood tests performed on the mother, father, and baby can be used to decide which pregnancies/babies are at risk.[4]

Management for pregnancies determined to be at risk remains controversial but may include a planned delivery and maternal avoidance of nonsteroidal anti-inflammatory drugs (NSAIDS) and aspirin during pregnancy. Management strategies have also included maternal intravenous immunoglobulin (IVIG) or maternal steroids and more invasive procedures such as fetal blood sampling and fetal platelet transfusions. The less invasive approach is currently favored.[3][4][5]

Management of the affected infant after birth depends on the specific signs and symptoms but may include periodic ultrasounds of the brain to check for bleeding, platelet transfusion, and IVIG. In the absence of intracranial bleeding, the prognosis is generally favorable and the platelet count usually improves within 8 to 10 days.[3]
Last updated: 10/9/2017

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Fetal and neonatal alloimmune thrombocytopenia. Click on the link to view a sample search on this topic.

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  1. Moise, Kenneth. What is NAIT. naitbabies.org. 2010; http://www.naitbabies.org/resources/what-is-nait/.
  2. Espinoza JP, Caradeux J, Norwitz ER, Illanes SE.. Fetal and Neonatal Alloimmune Thrombocytopenia. Reviews in Obstetrics and Gynecology. 2013; 6(1):e15-e21. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3651544/.
  3. Peterson JA, McFarland JG, Curtis BR, Aster RH. Neonatal alloimmune thrombocytopenia: pathogenesis, diagnosis and management. British journal of haematology. 2013; 161(1):3-14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3895911/.
  4. Paidas, Michael. Neonatal alloimmune thrombocytopenia: Parental evaluation and pregnancy management. UpToDate. March 17, 2017; http://www.uptodate.com/contents/neonatal-alloimmune-thrombocytopenia-parental-evaluation-and-pregnancy-management.
  5. Winkelhorst D., Murphy MF, Greinacher A, et al.. Antenatal management in fetal and neonatal alloimmune thrombocytopenia: a systematic review. Blood. March, 2017; 129(11):http://www.bloodjournal.org/content/bloodjournal/129/11/1538.full.pdf.