Optimizing office blood pressure thresholds to identify controlled ambulatory blood pressure in high-risk pregnancies with chronic hypertension.

Abstract

Background: Hypertensive disorders of pregnancy remain a leading cause of maternal and fetal morbidity and mortality worldwide. In women with chronic hypertension, adequate 24-h ambulatory blood pressure (ABPM) control has been associated with a reduced risk of adverse outcomes, including preeclampsia. However, the ability of office blood pressure (BP) measurements to reliably identify women with controlled ABPM during pregnancy remains uncertain. We conducted a retrospective cohort study including pregnant women with chronic hypertension evaluated before 20 weeks of gestation at a high-risk pregnancy center.

Methods: Office BP and 24-h ABPM were assessed using a standardized protocol at three gestational periods (14, 20, and 30 weeks). Controlled ABPM was defined by 24-h, daytime, and nighttime BP thresholds. Receiver operating characteristic curve analyses were performed to evaluate the discriminative ability of office systolic and diastolic BP to identify controlled ABPM and to explore potential cut-off values.

Results: Among 247 women with chronic hypertension, office BP demonstrated limited discriminatory performance across all gestational stages. Area under the curve values were consistently close to or below 0.5 for both systolic and diastolic BP, indicating poor classification ability. Cutoff values identified using the Youden index were clinically implausible and would have classified only a minimal proportion of women as having controlled ABPM. Even when clinically intuitive office BP thresholds were applied, sensitivity and specificity remained low. These findings indicate that office BP measurements cannot be considered a reliable surrogate for ABPM control in pregnant women with chronic hypertension.

Conclusion: Consequently, ABPM remains essential for accurate BP assessment and risk stratification, particularly during the second half of pregnancy.