OBJECTIVE: The impact of type 1 DM (T1DM) on thromboembolism in pregnancy is uncertain. We hypothesized that T1DM is associated with higher rates of thrombotic events during pregnancy and the postpartum period. STUDY DESIGN: This is a retrospective cohort study utilizing the National Inpatient Sample database from HCUP/AHRQ for 2017-2019. Pregnant and postpartum patients with a history of T1DM were compared to those without. The primary outcome was a composite diagnosis of any thrombotic disease (pulmonary embolism [PE], deep vein thrombosis [DVT], cerebral vascular thrombosis [CVT], or other thromboses). Secondary outcomes were the diagnosis of each individual type of thromboembolic event. Groups were compared via student's test, chi-squared, and logistic regression analyses, controlling for confounders including age, race, obesity, tobacco use, cHTN, asthma, anemia, and cesarean section. RESULTS: A total of 2,361,711 subjects met the criteria. Patients with T1DM encompassed 0.4% of subjects ( CONCLUSION: T1DM is associated with an increased risk of thromboembolic events in pregnancy. KEY POINTS: · T1DM is independently associated with VTE.. · PE and DVT are the most common events.. · T1DM has an impact on VTE similar to obesity..