OBJECTIVE: To study the relationship between thrombocytopenia in pregnancy associated with various causes and neonatal outcomes. METHODS: Medical records of 140 pregnant women with thrombocytopenia in pregnancy and the neonatal outcomes from January 2009 to December 2010 were reviewed retrospectively. The pregnant women were classified into four groups according to the causes of thrombocytopenia: gestational thrombocytopenia (GT; n=94), pregnancy with immune thrombocytopenic purpura (ITP; n=30), pregnancy with other hematological disease (aplastic anemia or myelodysplastic syndrome; n=12), and other causes (n=4): pregnancy induced hypertension syndrome, pregnancy with systemic lupus erythematosus, and pregnancy with alcoholic cirrhosis. The neonatal outcomes in the four groups were compared. RESULTS: The premature birth rates in the GT and the ITP groups were 11.3% and 16.7%, respectively. There was no significant difference between the two groups. The premature birth rate in the other hematological disease group was 53.8%, which was significantly higher than that in the GT (P<0.01) and the ITP groups (P<0.05). Congenital passive immune thrombocytopenia was found in 2 neonates (2%) in the GT group and in 4 neonates (13%) in the ITP group (P<0.05). In addition, other diseases were also observed in neonates in the ITP group, including 1 case (3%) of ITP and 1 case (3%) of Evans syndrome. Intracranial hemorrhage occurred in one neonate (8%) in the other hematological disease group. Neonatal lupus syndrome was found in 1 case (25%) in the other causes group. CONCLUSIONS: Thrombocytopenia in pregnancy associated with different causes may result in different neonatal outcomes.