Thrombocytopenia in Pregnancy: Mechanisms and Management

Thrombocytopenia is a common hematologic issue encountered by obstetricians and hematologists, detected in about 10% of all pregnancies. In the vast majority of cases, the thrombocytopenia will be attributed to gestational thrombocytopenia (GT), where the thrombocytopenia is mild, does not necessitate active management, and does not introduce maternal or fetal bleeding risk. Although GT is common, the specific mechanism responsible for it is not known with certainty, and therefore, differentiating it from other causes of thrombocytopenia can be challenging. Previously proposed explanations for GT suggest that a decrease in platelet count is universal in pregnancy, and women diagnosed with GT are simply those with a baseline platelet count on the lower end of normal range. This concept is challenged in this review, and a possible mechanism for GT is proposed. Additionally, a framework for approaching the diagnosis and management of thrombocytopenia in pregnancy is presented. •Thrombocytopenia in pregnancy is common, occurring in 7%-11% of all pregnancies.•Gestational thrombocytopenia is the most common etiology for thrombocytopenia in pregnancy, but the specific mechanism of this disorder has not been proven conclusively.•Immune thrombocytopenia occurs in about 1%-4% of all pregnancies and can be difficult to distinguish from gestational thrombocytopenia. The trend in platelet count over time can help differentiate the 2 diagnoses.•Other pregnancy-related causes for thrombocytopenia frequently include additional clinical features—such as hypertension, hemolysis, or evidence of end-organ damage.