Blood pressure trajectory during late pregnancy and the risk of severe preeclampsia-related complications: a retrospective cohort study

In non-pregnant populations, blood pressure variability is an independent predictor of adverse cardiovascular outcomes. However, its prognostic value for stratifying risk among women who have already developed hypertensive disorders of pregnancy (HDP) remains unclear. This study aimed to evaluate the association between blood pressure variability in late pregnancy and the risk of severe adverse outcomes in women with HDP. This was a retrospective cohort study of 3,118 pregnant women with HDP at a tertiary care center from 2018 to 2023. Blood pressure variability for systolic, diastolic, pulse pressure, and mean arterial pressure (MAP) was calculated from measurements after 24 weeks of gestation. Exposure was defined as high variability (≥ 90th percentile). The primary outcome was a composite of severe preeclampsia-related complications. The secondary outcome was HDP delivered an infant with low birth weight (LBW) (< 2500 g). Associations were assessed using overlap weighting-adjusted logistic regression to control for age, pre-pregnancy body mass index (BMI), and history of chronic hypertension. High blood pressure variability was significantly associated with an increased risk of the primary outcome, with the strongest association observed for MAP variability (adjusted odds ratio 4.25, 95% confidence interval 3.285.514), followed by diastolic, systolic, and pulse pressure variability. Similarly, high variability was associated with the secondary outcome of HDP complicated with LBW (MAP: OR 2.51, 95% CI 1.65–3.82). A dose-response analysis demonstrated a near-linear increase in risk with increasing variability thresholds. Results were robust across multiple sensitivity analyses, including propensity score matching. Among women with HDP, high blood pressure variability in late pregnancy, particularly in MAP, is a strong, independent risk marker for severe adverse outcomes. Assessing blood pressure variability may enhance risk stratification and identify candidates for more intensive monitoring.