Precursor prothrombin status in two mother-infant pairs following gestational anticonvulsant therapy.

Protein in vitamin K absence (PIVKA) is the prothrombin precursor found in plasma when carboxylation to prothrombin is impaired. We report on two cases in which mother-infant PIVKA concentrations were measured at birth after chronic anticonvulsant therapy during pregnancy. Maternal values were 2.4 and 4%, and infant values 20.0 and 18% in cases 1 and 2, respectively. This demonstrates that, despite the normal coagulation profiles previously described, mothers on chronic anticonvulsant therapy may have a subclinical carboxylation defect, while their infants are at risk for hemorrhagic disease. Estimation of maternal PIVKA levels may be of value for predicting risk of hemorrhage in the neonate.