Mortality Following Childbirth in Ontario: A 20-Year Analysis of Temporal Trends and Causes

OBJECTIVES: Maternal death during or after pregnancy is often preventable and accurate surveillance is key to prevention. We examined the number and causes of maternal death in Ontario over 20 years. METHODS: Retrospective cohort study including all hospital livebirths and stillbirths from 2002-2022 in the Canadian Institute for Health Information Discharge Abstracts (for hospitalizations) and National Ambulatory Care System (for emergency department encounters) linked to the Better Outcomes and Registry and Network births. Death was ascertained from childbirth to 365 days thereafter; all deaths were reviewed by at least 3 clinicians. RESULTS: There were 485 deaths among 2 764 214 live and stillbirths over 20 years-a maternal mortality ratio (MMR) of 17.5 per 100 000 (95% CI 16.0-19.2). There were 222 (45.8%) early deaths within 42 days of birth (MMR of 8.0 per 100 000; 95% CI 7.0-9.2), and 263 (54.2%) late deaths from 43 to 365 days after birth (MMR 9.5 per 100 000; 95% CI 8.4-10.7). Death was pregnancy-related in 169/485 cases (34.8%). Early death causes were predominantly hemorrhage, infection, preeclampsia, and pulmonary embolism. The top causes of 263 late deaths were cancer, injury, and cardiac arrest, or unknown. CONCLUSIONS: Most deaths within 1 year of childbirth are not related to obstetrical factors; however, pregnancy complications factor in early deaths. Causes of early and late deaths differ, but examining late deaths is equally important to identify factors not regularly examined in maternal mortality. As death in early pregnancy or outside hospitals is not reported, mortality is likely higher.