Risk factors associated with neonatal thrombocytopenia in pregnant women with immune thrombocytopenic purpura.

To characterize the risk factors associated with neonatal thrombocytopenia among pregnant women with immune thrombocytopenic purpura (ITP). We reviewed the records of ITP patients who delivered during 2006-2016 at our medical center. Of 253 pregnancies, median maternal age at diagnosis was 29 [25-33] years, 222 (87.7%) had previously-diagnosed ITP and 31 (12.3%) were diagnosed with new-onset ITP during pregnancy. Baseline characteristics were comparable between the groups except for a higher proportion of nulliparity among those with new-onset disease ( = .002). Maternal nadir platelet count was significantly lower among those with new-onset compared to previously diagnosed ITP (median 62 × 10/L versus 81 × 10/L,  = .005). Neonatal thrombocytopenia (<150 × 10/L) was encountered in 24 (9.5%) pregnancies and required treatment in 12 (50%) of them. Neonatal platelet count was directly correlated with maternal platelet count at delivery ( = 0.23,  = .01), with significantly lower maternal platelet count among those whose newborns experienced thrombocytopenia ( < .001). Neonatal thrombocytopenia followed a higher proportion of pregnancies of women with new-onset than previously diagnosed ITP (22.6 versus 7.7%,  = .02). In multivariate analysis, the presence of new-onset ITP (odds ratio [95% CI]: 4.88 (1.68, 14.16),  = .004) was the only independent predictor of the development of neonatal thrombocytopenia. Neonatal thrombocytopenia presented following almost one-tenth of pregnancies with ITP. New pregnancy-onset disease was the only prognostic marker for neonatal thrombocytopenia. This finding could contribute to risk stratification and individualized patient management.