Neonatal alloimmune thrombocytopenia is a rare but potentially life threatening condition in newborns. It can cause bleeding in the brain and long-term effects. Treatment usually involves a platelet or antibody transfusion.

Neonatal alloimmune thrombocytopenia (NAIT) is a rare but potentially severe condition that affects newborns. Doctors also call it fetal and neonatal alloimmune thrombocytopenia (FNAIT), as it can also affect fetuses.

“Thrombocytopenia” means that platelet counts are too low. Platelets are a component of blood that help with clotting. Without enough platelets, your risk of bleeding increases.

This article will explore NAIT’s causes, symptoms, diagnosis, and treatment.

While there are a few causes of low platelet counts in newborns, NAIT is the most common. It’s still rare, though, occurring in approximately 1 out of every 1,000 live births.

In NAIT, the birthing parent’s immune system identifies the baby’s blood platelets as a threat.

The baby’s platelets often contain an antigen inherited from the baby’s other biological parent. The birthing parent’s immune system doesn’t recognize this antigen, triggering the creation of antibodies that attack and destroy the fetus’s platelets.

This process can occur when the birthing parent is exposed to the baby’s blood during either pregnancy or childbirth.

Autoimmune vs. alloimmune thrombocytopenia

The prefix “auto” means “self.” Autoimmune thrombocytopenia, more commonly known as immune thrombocytopenia (ITP), occurs when the immune system wrongly targets and destroys its own platelets. This condition can affect anyone at any age.

The prefix “allo” means “other.” FNAIT occurs when someone else’s immune system — in this case, the birthing parent’s — targets and destroys a fetus’s or newborn’s platelets. This condition only occurs during pregnancy or in the weeks immediately after delivery.

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Mild cases of NAIT don’t always cause noticeable symptoms. Indeed, symptoms are more common with moderate to extremely low platelet levels.

If your newborn has thrombocytopenia, you might notice:

NAIT can cause life threatening bleeding in the brain, known as intracranial hemorrhage (ICH).

ICH in a fetus or newborn is a medical emergency. It can cause permanent neurological damage leading to:

Without treatment, ICH can be fatal.

ICH occurs in 8–22% of infants with NAIT who do not receive medical treatment. Complications tend to be more severe in firstborn children since NAIT often goes undiagnosed in first pregnancies.

Bleeding linked to thrombocytopenia can also occur in the gastrointestinal tract, lungs, and eyes, leading to additional complications.

According to 2018 research, birthing parents of fetuses with FNAIT may have an increased risk of miscarriage.

It’s difficult to detect thrombocytopenia in a fetus during pregnancy. An ultrasound may sometimes show issues in the brain, but doctors need further tests to determine the cause.

But in general, most pregnant people do not undergo fetal screening for FNAIT unless it occurred in a previous pregnancy. Doctors tend to diagnose it after birth in newborns with related symptoms.

If a doctor suspects NAIT, they will order blood tests for you, the other parent, and the newborn. A blood test can identify human platelet antigens and antibodies linked to FNAIT.

Newborns with thrombocytopenia typically receive a platelet transfusion. Since complications of thrombocytopenia can be severe, your doctor probably won’t wait to confirm NAIT before recommending the transfusion.

Treatment is different when alloimmune thrombocytopenia is detected in a fetus. The birthing parent might receive intravenous immunoglobulin (IVIG), take corticosteroids to reduce the immune system’s response, or both.

Babies with no complications who receive appropriate treatment are likely to make a full recovery as their platelet levels increase. This usually happens in 2–4 weeks.

Babies with NAIT who develop ICH are at greater risk of long-term neurological issues and even death in up to 35% of cases.

NAIT is a rare condition that affects newborns. It occurs when the birthing parent’s immune system destroys the fetus’s or newborn’s blood platelets.

Platelets help your blood to clot. A lack of platelets can lead to symptoms such as skin discoloration and bruising. In some cases, it can cause complications such as life threatening bleeding in the brain.

Newborns with thrombocytopenia usually receive a platelet transfusion to increase their platelet levels rapidly. Talk with a doctor to learn more about this treatment.