Ambulatory Blood Pressure Monitoring Defines Hypertension Phenotypes and Predicts a Composite Adverse Pregnancy Outcome

Objective: To delineate hypertension phenotypes defined by ambulatory blood pressure monitoring (ABPM) during pregnancy and assess their correlation with the duration until a composite adverse pregnancy outcome occurs. Design and method: Pregnant women were categorized into four phenotypes according to office blood pressure (OBP) and ABPM: normotension (n=108), sustained hypertension (SH) (n=87), white coat hypertension (WCH) (n=69), and masked hypertension (MH) (n=54). The principal composite outcome encompassed maternal mortality, fetal or neonatal mortality, preeclampsia or eclampsia, gestational diabetes, prematurity, fetal growth restriction, or dystocia resulting from uncontrolled hypertension. The follow-up duration (in days) was established from ABPM to the initial event. Phenotypes were analyzed through variance analysis for both ambulatory and OBP parameters. Kaplan–Meier survival analysis, utilizing log-rank and Breslow tests, compared the duration to the composite outcome among different phenotypes. Cox proportional hazards models evaluated the relationship between ambulatory blood pressure metrics and the composite outcome. Results: Ambulatory systolic and diastolic blood pressure (DBP) exhibited significant differences among phenotypes over twenty-four hours, daytime, and nighttime (all p<0.001). MH demonstrated ambulatory profiles akin to SH, whereas WCH resembled normotension. OBP was elevated in sustained and WCH relative to normotension and MH(both p<0.001). Time to the composite outcome varied significantly among phenotypes (log-rank p=0.001; Breslow p<0.001). In comparison to normotension, the composite outcome manifested earlier in SH (log-rank p=0.001; Breslow p=0.006) and MH (log-rank p=0.006; Breslow p=0.002), while WCH showed no significant difference from normotension (log-rank p=0.568; Breslow p=0.802). No significant difference was observed between SH and MH. In the entire cohort, elevated ambulatory systolic and DBP across twenty-four hours, daytime and night time were predictive of the composite outcome (twenty-four hour systolic blood pressure (SBP) p=0.008; twenty-four hour DBP p=0.012; daytime SBP p=0.010; daytime DBP p=0.017; nighttime SBP p=0.045; nighttime DBP p=0.035), whereas nocturnal blood pressure decline was not predictive. Conclusions: MH exhibits characteristics akin to SH and correlates with earlier negative outcomes, while WCH presents a risk level comparable to normotension. Elevated ABPM levels forecast a composite adverse pregnancy outcome, endorsing ABPM for enhanced risk stratification beyond office measurements.