The 2024 European guideline targets for ambulatory blood pressure monitoring and adverse pregnancy outcomes

Background The 2024 European Society of Cardiology (ESC) guideline introduced stricter “elevated blood pressure (BP)” thresholds. However, the clinical impact of maintaining BP within these targets, assessed by the percentage of time in the target range (PTTR), on maternal and fetal outcomes remains unclear. Purpose This study aimed to evaluate the association between PTTR derived from the 2024 ESC criteria and adverse pregnancy outcomes (APOs) and the risk of subsequent antihypertensive therapy initiation. Methods This retrospective cohort study included 1,856 high-risk pregnant women. The study quantified ambulatory BP-derived PTTR based on the 2024 ESC elevated BP and hypertension thresholds, and employed multivariable Cox proportional hazards models to estimate the risk of initiating subsequent antihypertensive therapy. Furthermore, this study analysed associations with APOs using restricted cubic splines and logistic regression. Results PTTR showed mild to moderate negative correlations with office BP. The lowest PTTR tertile was significantly associated with a higher risk of subsequent antihypertensive therapy initiation (HR 7.28 for the elevated BP threshold and HR 12.17 for the hypertension threshold), particularly during the 28-34-week window. PTTR-hypertension demonstrated a non-linear decreasing association, identifying a 66% safety threshold below which risks increased. In contrast, PTTR-elevated BP exhibited a U-shaped relationship, suggesting increased risk at both low and high BP exposure levels. Moreover, PTTR-hypertension outperformed office BP in predicting maternal outcomes (AUC 0.757 vs 0.714). Conclusions Comparing the 2024 elevated BP and hypertension ambulatory BP thresholds, the hypertension-based PTTR provides a more reliable reference for risk stratification and monitoring in high-risk pregnancies. It serves as a practical ambulatory BP marker to guide BP management, whereas strict adherence to elevated BP targets challenges the 'lower is better' paradigm due to potential fetal risks.