Reference-range of arterial stiffness by cardio-ankle vascular index in normal pregnancy

To establish the arterial stiffness, represented by the cardio-ankle vascular index (CAVI) at various gestational ages among low-risk pregnant women. The second objective is to construct the reference range of mean arterial pressure and maternal heart rate during pregnancy.

This cross-sectional study was conducted on low risk pregnant Thai women, meeting the following inclusion criteria: 1) singleton pregnant women aged 18 years old or over; 2) gestational age between 11 and 40 weeks; 3) low-risk pregnancy without any underlying medical diseases; and 4) known final pregnancy outcomes. Pregnancy-induced hypertension, gestational diabetes and fetal growth restriction were excluded. The mean CAVI, mean arterial pressure (MAP), and heart rate were measured at each gestational age.

A total of 329 measurements for each parameter were available for analysis. CAVI was significantly correlated with gestational age with the best fitted model: CAVI = 6.952 - 0.076(GA) + 0.001(GA)²; SD = 0.742 (R² = 0.049; p-value < 0.001). The maternal age and pre-pregnancy BMI were correlated with CAVI. CAVI gradually increased with maternal age and decreased with increasing body mass index (BMI). The MAP and heart rate of normal pregnancy in each gestation were conducted.

The reference range of CAVI in normal pregnancies as a function of gestational age and the model for predicting CAVI based on multiple regression analysis are constructed and presented. These reference ranges may be useful in predicting risk of cardiovascular disorders during pregnancy.