Comparison of platelet counts in first and second newborns of mothers with immune thrombocytopenic purpura.

Overview

OBJECTIVE: This study was designed to estimate the predictive value of the first neonatal platelet count for the second neonate in women with immune thrombocytopenic purpura (ITP). METHODS: Data of 34 patients, repeatedly pregnant while they had ITP, were prospectively collected in two study centers between 1984 and 1995. The main outcome measure was neonatal thrombocytopenia. RESULTS: Early neonatal platelet counts (i.e., umbilical cord count or count during the first 24 hours of life) between siblings were correlated (r = .73; 95% confidence interval (CI) for the correlation coefficient 0.52, 0.86). Severe thrombocytopenia (less than 50 x 10(9)/L) at birth did not occur in any of the 27 siblings of infants with birth platelet levels above 50 x 10(9)/L. Also the second sibling's nadir neonatal platelet counts during the first 2 weeks of life were correlated with those of the first sibling (r = .76; 95% CI for the correlation coefficient 0.58, 0.88). In those cases in which the first sibling had a lowest platelet count above 100 x 10(9)/L (n = 19), the second sibling never became thrombocytopenic. CONCLUSION: The platelet count of the first sibling can be used to counsel women with ITP, and may be helpful in their management.