Background NAIT is caused by maternal alloantibodies directed against fetal platelet antigens that cross the placenta. Its incidence is estimated to be around one in 350–2000 live births.

Most cases occur in an unexpected way, and an accurate diagnosis and treatment are essential to reduce mortality or intracerebral hemorrhage, which can occur in 10 to 20% of cases.

Study Retrospective study with clinical chart review of newborns with NAIT diagnosed between January 2000 and December 2007.

Results 7 cases were identified (1:5986 newborns). 2 cases were first pregnancies, and there was history of thrombocytopenia in previous child in 2 cases. It was an occasional finding in 4 cases. 3 cases had cutaneous purpura and one presented with GI hemorrhage. 2 of those had symptoms at the time of birth and one at 8 hours.

In every case a cerebral ultrasound was done and no cases had intracerebral hemorrhage.

Antibodies HPA-1a were identified in 4 cases, the other had positive alloantibodies but no genotyping was done. The lowest platelet value was 6000–40 000 and occur in mean at 48 hours.

In 2 cases treatment consisted of platelet transfusion (PT), immunoglobulin (IG) and systemic steroids, in 2 cases PT and IG, and in 3 no treatment was done.

Conclusions The incidences found revealed that this condition is underdiagnosed in this population. Since the prenatal screening is controversial and because it can occur with no evident clinical manifestations a high index of suspicion is needed to start appropriate treatment and to prevent severe cases of thrombocytopenia in future pregnancies.