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OBJECTIVE: To characterize the risk factors associated with neonatal thrombocytopenia among pregnant women with immune thrombocytopenic purpura (ITP). STUDY DESIGN: We reviewed the records of ITP patients who delivered during 2006-2016 at our medical center. RESULTS: Of 253 pregnancies, median maternal age at diagnosis was 29 [25-33] years, 222 (87.7%) had previouslydiagnosed 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 (P1⁄40.002). Maternal nadir platelet count was significantly lower among those with new-onset compared to previously diagnosed ITP (median 62 X 10/L vs. 81 X 10/L, P1⁄40.005). Neonatal thrombocytopenia (<150 X 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 (r1⁄40.23, P1⁄40.01), with significantly lower maternal platelet count among those whose newborns experienced thrombocytopenia (P<0.001). Neonatal thrombocytopenia followed a higher proportion of pregnancies of women with new-onset than previously diagnosed ITP (22.6% vs. 7.7%, P1⁄40.02). In multivariate analysis, the presence of new-onset ITP (odds ratio [95% CI]: 4.88 (1.68, 14.16), P1⁄40.004) was the only independent predictor of the development of neonatal thrombocytopenia. CONCLUSION: 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.