The most common problem encountered during frequent obstetrical consultations and when pregnant women come to the hematology clinic is thrombocytopenia. Thrombocytopenia occurs in 6-10% of pregnant women and is the most common hematologic abnormality during pregnancy, surpassing even anemia. The diagnosis and management of these patients is particularly prudent due to concerns about the use of medications during pregnancy and the fact that some “thrombocytopenia” often conceals a serious underlying disease. The causes of thrombocytopenia in pregnancy are similar to those of thrombocytopenia in the general population, including reduced production, excessive destruction, abnormal distribution, and excessive consumption. However, due to changes in hormonal levels and immune environment during pregnancy and complications specific to pregnancy, the number of cases of thrombocytopenia caused by immune destruction and “depletion” mechanisms is significantly increased, while the number of cases of thrombocytopenia caused by mechanisms such as decreased production (e.g. leukemia) and abnormal distribution (e.g. hypersplenism) is not significantly different from that of the general population. There is no significant difference in the general population. Immune thrombocytopenia (ITP) is one of the causes of thrombocytopenia in pregnancy. Secondary ITP is usually associated with viral or bacterial infections (human immunodeficiency virus, hepatitis C virus and Helicobacter pylori) and autoimmune diseases (e.g., systemic lupus erythematosus, antiphospholipid antibody syndrome) and is mostly present before pregnancy, with only 1/3 of patients being first diagnosed at the time of pregnancy. ITP tends to worsen during pregnancy and diminish with termination of pregnancy. Therefore, it is important to fully inform women who have these conditions and intend to become pregnant about the risks of pregnancy. Glucocorticoids are contraindicated during the first trimester of pregnancy for fear of affecting fetal development. If platelets fall below a safe level (<20-30×109/L), it can be very difficult to manage, and only intravenous gammaglobulin is safe. The efficiency of platelet transfusion at this time is very low, and repeated platelet transfusion may also result in "ineffective platelet transfusion". If the fetus is mature, termination of pregnancy should be chosen; if the fetus is immature, the mother and fetus should weigh the pros and cons of continuing the pregnancy and terminating it to ensure the safety of both to the greatest extent possible. In patients with myelodysplastic syndromes (MDS) and aplastic anemia, the mechanism of thrombocytopenia is also related to immune abnormalities. These patients face similar problems to those with immune thrombocytopenia once they become pregnant and will be more difficult to manage because of the poor response to glucocorticoid and gammaglobulin therapy, so these patients need to be more cautious about whether to become pregnant. A normal platelet count before pregnancy and thrombocytopenia in pregnancy may be a physiologic process. In normal pregnancy, there is a physiological decline in platelet count and some pregnant women's platelets may fall below the normal range, which is called "thrombocytopenia of pregnancy". remission after delivery, and can be diagnosed after other etiologies have been ruled out. Thrombocytopenia in pregnancy may also be a manifestation of certain serious conditions specific to pregnancy or to which pregnancy is predisposed, such as pre-eclampsia, HELLP syndrome, thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), acute fatty liver during pregnancy, and disseminated intravascular coagulation (DIC). In these diseases, under the effect of certain factors related to pregnancy, platelets are activated and a series of reactions such as adhesion, aggregation and release occur, and finally platelet thrombosis is formed; or along with endothelial damage and activation of coagulation pathways, fibrin thrombosis is formed, which can consume platelets and form "thrombotic microangiopathy" and cause organ The thrombocytopenia may be the first cause of thrombotic microangiopathy, resulting in organ damage or even failure, which can threaten maternal life. Early identification of the mechanism of thrombocytopenia and further interventions including plasma exchange, fresh plasma transfusion, termination of pregnancy or even hysterectomy are often related to maternal life safety. In conclusion, the etiology of thrombocytopenia in pregnancy is diverse and can be a benign process or a predictor of a dangerous outcome, therefore, early identification and identification of the mechanism of its occurrence determines not only the implementation of interventions but also the prognosis of the patient.