Blood pressure and heart rate variability during gestation in healthy and hypertensive pregnant women

The evaluation of predictable variability in blood pressure (BP) and heart rate (HR) by the use of ambulatory devices, and the proper processing of the time series thus obtained, can be useful for the early assessment of hypertensive complications in pregnancy. The authors have used this approach to analyze 759 series of BP and HR sampled by ambulatory monitoring for about 48 hours every four weeks after the first obstetric visit in 71 women with uncomplicated pregnancies and 42 women with gestational hypertension or preeclampsia. The pattern of variation along gestation of the 24-hour mean of BP for each group of pregnant women was established by polynomial regression analysis. This method revealed a BP predictable pattern of variation with gestational age: for normotensive pregnant women, results indicate a steady decrease in BP up to the 21st week of pregnancy, followed by an increase in BP up to the day of delivery. In pregnancies complicated with gestational hypertension or preeclampsia, the 24-hour mean of BP is stable until the 22nd week of pregnancy, and then correlated with gestational age indicating a significant linear increase of BP in the second half of pregnancy. These differences between uncomplicated and complicated pregnancies offer new endpoints for an early identification of gestational hypertension and preeclampsia.