Trends in rate of hypertensive disorders of pregnancy and associated morbidities in Canada: a population-based study (2012-2021)

Background: Hypertensive disorders of pregnancy (HDP) are a leading cause of severe maternal morbidity (SMM). We sought to explore trends in HDP and related morbidity outcomes in Canada. Methods: In this retrospective population-based study, we used hospital discharge data from Canada, excluding Quebec, to identify females who had an HDP diagnosis during a birth admission between 2012 and 2021. We analyzed temporal and geographical trends in HDP, as well as temporal trends in adverse outcomes associated with HDP. Results: Among 2 804 473 hospital admissions for birth between 2012 and 2021, the rate of any HDP increased from 6.1% to 8.5%, including pre-existing hypertension (0.6% to 0.9%), gestational hypertension (3.9% to 5.1%), and preeclampsia (1.6% to 2.6%). For 2017-2021 combined, relative to Ontario (6.9%), HDP were significantly more prevalent in nearly all other Canadian regions. For example, in Newfoundland and Labrador, the rate was 10.7% (unadjusted rate ratio 1.56, 95% confidence interval 1.49-1.63). Among females with any HDP, rates of cesarean delivery rose from 42.0% in 2012 to 44.3% in 2021, as did acute renal failure (0.4% to 0.6%), while rates of early preterm delivery, intrauterine fetal death, maternal hospital length of stay ([greater than or equal to] 7 d), admission to the maternal intensive care unit, severe hemorrhage, and SMM trended downward. Interpretation: The rate of HDP has risen across Canada, with a concomitant decline in some HDP-associated morbidities. Ongoing surveillance of HDP is needed to assess the factors associated with temporal trends, including the effectiveness of evolving HDP prevention and management efforts.
Hypertensive disorders of pregnancy (HDP) include pre-existing (chronic) hypertension, gestational hypertension, and preeclampsia or eclampsia. Globally, hypertensive disorders affect 5%-10% of pregnancies and are responsible for more than 50 000 [...]