Maternal Cardiovascular Mortality: A Longitudinal Cohort Study of Risk Factors and Incidence

INTRODUCTION Cardiovascular mortality is responsible for a considerable fraction of maternal deaths during pregnancy, but the incidence and risk factors of maternal cardiovascular mortality are understudied. METHODS The study included 2,975,361 pregnancies in Quebec, Canada, between 1989 and 2021 (analyzed in 2025). The outcome was maternal cardiovascular mortality during or within one year of pregnancy, including early (1-42 days) and late postpartum (43-364 days). Risk factors included cardiac complications, renal failure, and other cardiovascular and noncardiovascular severe maternal morbidity, nonsevere pregnancy complications such as gestational diabetes and mild preeclampsia, as well as other characteristics. Using adjusted Cox regression models, hazard ratios (HR) and 95% confidence intervals (CI) were estimated for the association between pregnancy characteristics and maternal cardiovascular mortality. RESULTS A total of 93 maternal cardiovascular deaths occurred during the study, for an overall mortality rate of 3.1 per 100,000 pregnancies. Cardiovascular deaths were evenly distributed during pregnancy/early postpartum (51.6%) and late postpartum (48.4%). Cerebrovascular disorders (35.5%) were the leading cause of death, followed by myocardial infarction, arrhythmias, and other cardiac complications (32.3%), thromboembolic complications (22.6%), and heart failure (9.7%). Severe maternal cardiovascular morbidity was the strongest risk factor for cardiovascular mortality (HR 152.3, 95% CI 88.5-262.1), particularly during pregnancy/early postpartum (144.8 per 10,000 pregnancies). CONCLUSIONS Maternal cardiovascular mortality is prevalent both during pregnancy and postpartum, with the strongest risk factor being severe maternal cardiovascular morbidity. Reducing cardiovascular deaths requires tackling severe maternal cardiovascular morbidity during pregnancy.