Thrombocytopenia is a common finding in pregnancy, occurring in approximately 7–10% of pregnancies. It may be a diagnostic and management problem, and has many causes, some of which are specific to pregnancy. Although most cases of thrombocytopenia in pregnancy are mild, and have no adverse outcome for either mother or baby, occasionally a low platelet count may be part of a more complex disorder with significant morbidity and may be life-threatening. Overall, about 75% of cases are due to gestational thrombocytopenia, 15–20% secondary to hypertensive disorders; 3–4% due to an immune process, and the remaining 1–2% made up of rare constitutional thrombocytopenias, infections and malignancies. In this review, a diagnostic approach to investigating thrombocytopenia in pregnancy is presented, together with antenatal, anaesthetic and peri-natal management issues for mother and baby, followed by a detailed discussion on the specific causes of thrombocytopenia and the management options in each case.