Temporal Trends in Hypertensive Disorders of Pregnancy in British Columbia, Canada

Rates of hypertensive disorders of pregnancy (HDPs) have consistently increased over the past several decades. This study investigated temporal trends in HDPs in British Columbia (BC), Canada.

We studied all women who delivered at 20-44 weeks' gestation in BC from 2012/13 to 2023/24 (N = 515 778). Data were obtained from the BC Perinatal Database Registry. Conditions of interest included chronic hypertension (CH), gestational hypertension, preeclampsia (PE), PE superimposed on CH, PE with severe features (including eclampsia), and hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome. Temporal trends were assessed using logistic regression, and we examined how trends changed after adjusting for maternal risk factors such as age, parity, pre-pregnancy body mass index, twin pregnancy, and other factors. Interrupted time series analyses assessed changes associated with the onset of the COVID-19 pandemic.

Gestational hypertension increased from 48.1 per 1000 pregnancies in 2012/13 to 77.7 per 1000 pregnancies in 2023/24, while PE rose from 17.6 to 41.6 per 1000 pregnancies. Increases were also observed in CH, PE superimposed on CH, and PE with severe features, though the rate of the composite of PE with severe features and HELLP syndrome remained relatively stable. Increasing trends were attenuated but persisted after adjustment for maternal risk factors. A decreasing trend was observed in the adjusted odds of HELLP syndrome (adjusted OR 0.978; 95% CI 0.963-0.992 per year). Pandemic onset was associated with small declines in rates of PE and superimposed PE, though increasing trends continued thereafter.

The growing burden of HDPs implies an increased need for patient monitoring, prevention strategies, and accurate surveillance of disease severity.