Temporal Variations in Incidence andOutcomes of Critical Illness Among Pregnant and Postpartum Women inCanada: A Population-Based Observational Study

Abstract

Objective: Pregnancy-associated morbidity results in hundreds of thousands of deaths annually worldwide. Reducing maternal mortality is a key United Nations Millennium Development Goal. Although maternal mortality has declined in high-income countries, contemporary estimates of maternal morbidity and mortality trends in Canada are lacking.

Methods: This population-based study investigated all antepartum, peripartum, and postpartum women presenting to an acute care hospital in Canada from April 1, 2004 to March 31, 2015. The primary outcome was the change in rates of severe maternal morbidity over time. Secondary outcomes included severe maternal mortality and intensive care unit admission, including by province and territory (level of evidence: II2).

Results: The cohort comprised 2 035 453 mothers with 3 162 303 pregnancies. There were 17.7 per 1000 episodes of severe maternal morbidity, with annual increases of 1.3% (95% confidence interval [CI] 0.60-2.0) for severe maternal morbidity. The maternal mortality rate was 6.2 per 100 000 deliveries and stable over time (estimated percentage of annual change of -0.46%; 95% CI -5.0 to 4.3). The most common causes of severe maternal morbidity were postpartum hemorrhage (5.5 per 1000 deliveries), sepsis (3.8 per 1,000 deliveries), and cardiac failure (1.5 per 1000 deliveries). Severe maternal morbidity varied across Canadian regions but was highest in the Territories at 22.8 per 1000 deliveries.

Conclusion: Although maternal mortality has been stable in Canada over time, rates of severe maternal morbidity are increasing and are associated with substantial regional variation, with the highest rates experienced by women in the northern Territories.

Keywords: Severe maternal morbidity; intensive care unit; maternal mortality; temporal trend; variation.