A Screening and Intervention Program Reducing Mortality and Serious Morbidity Associated with Neonatal Alloimmune Thrombocytopenia.

Background: Neonatal alloimmune thrombocytopenia (NAIT) is most frequently caused by antibodies against the human platelet antigen (HPA) 1a. The objective of the present study was to identify HPA 1a negative women, and to offer them an intervention program aimed to reduce morbidity and mortality of NAIT.

Methods: A total of 100,448 pregnant women were HPA 1 typed. The HPA 1a negative women were screened for anti-HPA 1a, which was quantified when present. Immunized women were referred to a university hospital for clinical follow-up, including ultrasonographic examination of the fetal brain. Caesarean section was performed 2–4 weeks prior to term with platelets from HPA 1bb donors reserved for immediate transfusion if petechiae were present and/or if platelet count was < 35 × 10⁹/L.

Results: Of all women typed 2.1% were HPA 1a negative. Anti-HPA 1a was detected in 210 of 1,990 HPA 1a negative women. A total of 170 pregnancies in 154 HPA 1a negative women were managed according to the intervention program. These women gave birth to 161 HPA 1a positive children of whom 55 had severe thrombocytopenia (<50 × 10⁹/L) including two with ICH. There were no intrauterine deaths. In 13 previously published prospective studies comprising 131,465 women of whom 2,290 were HPA 1a negative, there were 10 cases with severe NAIT-related complications (3 intrauterine deaths and 7 neonates with ICH), which are significantly higher than in our study (p < 0.05).

Conclusions: The screening and intervention program seems to reduce mortality and serious morbidity associated with NAIT.