〔Abstract〕 Objective To investigate the etiology of pregnancy complicated with moderate to severe thrombocytopenia and its influence on maternal and fetal outcomes. Methods The clinical data of 123 pregnant women with thrombocytopenia who delivered in the Department of Obstetrics, Shenzhen Second People's Hospital from January 2015 to May 2022 were retrospectively analyzed. According to the lowest platelet count (PLT) during pregnancy, they were divided into mild thrombocytopenia group with 79 cases and moderate to severe thrombocytopenia group with 44 cases. To analyze the etiology of pregnancy complication moderate to severe thrombocytopenia and its influence on maternal and fetal outcomes. Results Gestational thrombocytopenia (GT) was the most common cause of pregnancy complicated with moderate to severe thrombocytopenia, followed by idiopathic thrombocytopenic purpura (ITP) and hypertensive disorders pregnancy (HDP). There was no statistically significant difference in age, body mass index (BMI), pregnancy time, production time between moderate and severe thrombocytopenia group and mild thrombocytopenia group during pregnancy (P > 0.05), but the gestational age at diagnosis in the moderate to severe group was earlier than that in the mild group, and the incidence of mucocutaneous bleeding was higher than that in the mild group, and the differences between the two groups were statistically significant (P < 0.05). In terms of pregnancy outcomes, the mean gestational age at delivery was earlier in the moderate to severe group than in the mild group, the rate of postpartum hemorrhage, preterm birth and the incidence of neonatal thrombocytopenia in the moderate to severe group were higher than those in the mild group, and the PLT values before delivery and on the first day after delivery were lower than those in the mild group, the differences were statistically significant (P < 0.05). The use of blood products during pregnancy and delivery, cesarean section rate, and spinal anesthesia rate, the differences were statistically significant between the two groups (P < 0.05). Conclusion With the decrease of platelet level, the risk of adverse pregnancy outcomes in pregnant women with thrombocytopenia increases. For pregnant women with thrombocytopenia, especially those with moderate to severe thrombocytopenia, it is necessary to identify the etiology as early as possible, intervene reasonably and effectively, and choose the timing of termination of pregnancy and delivery mode individually to improve maternal and fetal outcomes.