Thrombocytopenia is the second most common hematologic abnormality in pregnancy, occurring in up to 10% of pregnancies. More severe thrombocytopenia (platelet counts <100,000 × 109/L) is observed in <1% of uncomplicated pregnancies, with platelet counts <80,000 × 109/L in <0.1%. Gestational thrombocytopenia is the most common etiology of thrombocytopenia in pregnancy, accounting for approximately 70–80% of cases, and has an overall benign course, not requiring specific management strategies and resolving postpartum. Although there is no established minimum platelet count for gestational thrombocytopenia, the diagnosis is less common with platelet counts <100 × 109/L and rare with platelet counts <70–80 × 109/L. Hypertensive disorders of pregnancy, including preeclampsia and the hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome, are the second most common cause of thrombocytopenia in pregnancy, usually diagnosed after 20 weeks gestation. HELLP presents with a thrombotic microangiopathy, which can be difficult to distinguish from primary thrombotic microangiopathies, such as atypical hemolytic uremic syndrome (also known as complement-mediated thrombotic microangiopathy) and thrombotic thrombocytopenia purpura, which are not unique to pregnancy but occur with increased frequency. The differential diagnosis of thrombocytopenia in pregnancy hinges on gestational age, severity, maternal comorbidities, and whether there is a pre-existing history of thrombocytopenia. Management of thrombocytopenia during pregnancy is associated with unique considerations and toxicities of relevance to both the mother and fetus. Though thrombocytopenic disorders may severely affect some pregnancies, accurate diagnosis and prompt therapy usually lead to successful outcomes.