NEONATAL THROMBOCYTOPENIA

Causes:

I. Maternal ITP

II. Neonatal Alloimmune Thrombocytopenia

1. Results from maternal alloimmunization to fetal platelet antigens (HPA-1, HPA-2)
2. Incidence 1:1,000-2,000 live births
3. Can occur during a first pregnancy--unlike Rh-alloimmunization
4. Maternal platelet count generally normal
5. Neonatal thrombocytopenia usually profound; clinical manifestations usually evident within hours after birth (e.g. petechiae or ecchymoses over the presenting part)
6. Intracranial hemorrhage occurs in 10-20% of cases; can occur in utero
7. Recurrence risk is high in subsequent pregnancies if the subsequent fetus carries the pertinent antigen

(Source: ACOG Practice Bulletin #6, 9/99)