Circadian blood pressure adaptation and arterial stiffness in pregnancy: An exploratory study

Background Maternal vascular adaptation influences blood pressure (BP) regulation and arterial stiffness. Ambulatory blood pressure monitoring (ABPM) allows calculation of the Ambulatory Arterial Stiffness Index (AASI), a non-invasive surrogate of vascular compliance. Data on these parameters in Latin American populations remain scarce. Methods This exploratory study included 81 women (36 nonpregnant; 45 healthy pregnant). 24-hour ABPM assessed BP, circadian patterns, and AASI. Comparisons were made by pregnancy status and gestational age (< 20 vs. ≥20 weeks) using Welch tests and bootstrap confidence intervals. Results Mean 24-hour BP was comparable between pregnant (111/66 mmHg) and nonpregnant women (115/69 mmHg; p > 0.05). AASI values were also similar between groups (0.33 ± 0.12 vs. 0.31 ± 0.18; p > 0.05), though pregnant women exhibited significantly reduced variability confirmed by bootstrap analysis. After 20 weeks, a significant shift from dipper to non-dipper systolic pattern occurred (p < 0.00001, Cramer’s V = 0.703). Circadian patterns and AASI were not significantly associated. Conclusions Pregnancy involves distinct hemodynamic shifts, specifically a non-dipper pattern after mid-gestation and reduced AASI variability. These exploratory findings provide a physiological baseline for vascular adaptation in this population, informing future research on hypertensive disorders.