Circulating antiplatelet antibodies in pregnant women with immune thrombocytopenic purpura as predictors of thrombocytopenia in the newborns.

Newborns from mothers with immune thrombocytopenic purpura (ITP) have a risk of thrombocytopenia due to passage of maternal antiplatelet antibodies into fetal/neonatal circulation. We looked for predictors of neonatal thrombocytopenia (nTP) in pregnant women with ITP. One hundred pregnant women with platelet count <100 × 109 /l, no non-immune causes of thrombocytopenia and increased platelet associated IgG (PA-IgG) were included in the study. Thirty seven and 63 of them gave birth to babies with and without nTP, respectively (nTP+ and nTP- groups). Platelet count, mean platelet volume, PA-IgG, antiplatelet circulating antibodies (cAB), time of ITP onset (before or during pregnancy), and frequency of corticosteroid treatment were compared in these groups. There were no differences in all test parameters between nTP+ and nTP- groups except cAB. These antibodies were detected in 33 out of 37 in nTP+ group and in 2 out of 63 mothers in nTP- group (p < 0.001). The sensitivity of this test was 89% and its specificity was 97%. A strong reverse correlation (r = -0.749, p < 0.001) was established between maternal cAB titer and neonatal platelet count. Antibodies against glycoproteins IIb-IIIa and/or Ib were identified in antigen specific MAIPA (Monoclonal Antibody Immobilization of Platelet Antigen) assay only in 10 out of 19 (53%) test sera with cAB. Antiplatelet cAB in pregnant women with ITP could serve as reliable predictors of nTP in their babies.