Baroreflex sensitivity, heart rate, and blood pressure variability in normal pregnancy

Heart rate variability is a relevant predictor of cardiovascular risk in hu mans, However, to use heart and blood pressure (BP) variability or barorefl ex sensitivity as markers for hypertensive pregnancy disorders, it is first necessary to describe these parameters in normal pregnancy. To accommodate the complexities of autonomic cardiovascular control we added parameter do mains of nonlinear dynamics to conventional linear methods of time and freq uency domains. The BP of 27 women with normal pregnancy and 14 nonpregnant women were monitored at a high resolution (200 Hz sampling frequency) using a Portapres for 30 min. The pregnant women were divided into groups of 32 or less or greater than 32 weeks of gestation. Pregnant and nonpregnant wom en were classified into subclasses of maternal age of less than 28 or 28 or more years. Except for two single parameter domains, we found no significa nt differences in heart rate and BP variability for pregnant women with dif ferent gestational age or different maternal age. Moreover, no significant differences in spontaneous baroreflex sensitivity could be found between pr egnant women regardless of either their age or gestational age. In contrast ,, all measures of nonlinear dynamics of heart rate variability as well as all parameter domains of spontaneous baroreflex sensitivity showed signific ant changes between pregnant and nonpregnant women, whereas BP variability did not differ between those groups. This complex assessment of autonomic c ardiovascular regulation has shown that the parameters tested are stable in the second half of normal pregnancy, and might have the potential to be ex cellent indicators of pathophysiologic conditions. Am J Hypertens 2000;13:1 218-1225 (C) 2000 American Journal of Hypertension, Ltd.