Learn The BasicsFetal and neonatal alloimmune thrombocytopenia (FNAIT) is a rare disease in which the body of a pregnant woman mistakenly attacks her baby’s platelets (blood fragments that are crucial for blood clotting.) This leads to low platelet counts and can increase the risk of heavy bleeding, which can have very serious long-term effects or even be life-threatening.
The signs and symptoms of FNAIT may be mild or severe and include bleeding, bruising or widespread petechiae and purpura. It is difficult to predict which infants will develop severe symptoms.
FNAIT does not cause any symptoms in the mother unless the disease progression is very severe, in which case it could lead to a miscarriage.
Thrombocytopenia
Thrombocytopenia or a low platelet count is defined as fewer than 150,000 platelets per microliter of circulating blood. Babies affected by FNAIT can have as little as 30,000 platelets per microliter of circulating blood, in which case they should immediately undergo a platelet transfusion.
Bleeding
Bleeding may occur as a result of thrombocytopenia before, during or after birth in babies affected by FNAIT.
Passage through the birth canal can cause enough stress to trigger bleeding in a baby that has very low platelets.
After birth, simple procedures such as a heel prick, a vitamin shot or circumcision can cause bleeding that cannot be stopped.
Because the mother’s antibodies can stay in the body of the newborn baby for several weeks, they may continue to attack their platelets putting them at risk of heavy bleeding for up to four weeks.
Bruising
A baby with FNAIT can be born with bruises, also called hematomas, and they can also bruise easily due to thrombocytopenia. The bruising is caused by bleeding under the skin.
These bruises will eventually disappear as the platelet counts of the baby recover.
Petechiae and purpura
Petechiae are red pinpoint spots that appear on the skin while purpura are larger areas of purple skin discoloration.
These can cover most of the body of the baby with FNAIT and appear within a few hours after birth.
However, FNAIT is not the only cause of petechia and purpura, as they can also occur as a result of abnormalities in plasma coagulation factors and blood vessels.
Severe symptoms of FNAIT
Though bruising is a common symptom of FNAIT, it can also result in more severe symptoms.
For example, babies with FNAIT may develop a condition known as cephalohematoma, in which blood collects under the scalp, causing a bulge to form on the baby’s head. In more severe cases, babies may have signs of petechiae or purpura along with cephalohematoma.
The most severe symptom of FNAIT is intracranial hemorrhage (ICH) in which bleeding occurs in the brain. This may occur in 10 to 25% of FNAIT cases and can cause brain damage or even death. Babies who have cephalohematoma may be at increased risk of ICH.
The long-term neurological complications of FNAIT-related ICH include cerebral palsy, intellectual disability, seizures and hearing loss.
Bleeding due to FNAIT-associated thrombocytopenia may also occur in other vital organs such as the gastrointestinal tract, lungs or eyes.
Symptoms of bleeding in the lungs may include coughing up blood. If bleeding occurs in the eyes, it can cause blindness.
The gastrointestinal tract, which includes the esophagus, stomach, small intestines and large intestines, is the most common site of severe bleeding in FNAIT following ICH. Symptoms of gastrointestinal bleeding include vomit with blood or bloody stools.
