BLOOD-PRESSURE VARIABILITY DURING GESTATION IN HEALTHY AND COMPLICATED PREGNANCIES

The evaluation of predictable variability in blood pressure by the use of ambulatory devices, and the proper processing of the time series t hus obtained, can be useful for the early assessment of hypertensive c omplications in pregnancy. We have used this approach to quantify a pr edictable pattern of blood pressure and heart rate throughout pregnanc y in clinically healthy women as well as in pregnant women who develop ed gestational hypertension or preeclampsia. We analyzed 503 blood pre ssure series from 71 healthy pregnant women and 256 series from 42 wom en who developed gestational hypertension or preeclampsia. Blood press ure monitoring (48-hour) was done once every 4 weeks after the first o bstetric consultation. The pattern of variation along gestation of the 24-hour mean of blood pressure for groups of normotensive and hyperte nsive pregnant women was established by polynomial regression analysis . This method revealed predictable patterns of variation of 24-hour me ans with gestational age: for normotensive pregnant women, results ind icate a steady decrease in blood pressure up to the 21st week of pregn ancy, followed by an increase in blood pressure up to the day of deliv ery. This pattern of variation is not found in pregnancies complicated with gestational hypertension or even preeclampsia: the 24-hour mean of blood pressure is stable until the 22nd week of pregnancy and then correlated with gestational age, indicating a significant linear incre ase of blood pressure in the second half of pregnancy. For both health y and complicated pregnancies, heart rate slightly increases until the end of the second trimester, and it is stable thereafter. This study confirms and extends to ambulatory everyday life conditions the predic table pregnancy-associated variability in blood pressure. The differen ces between uncomplicated and complicated pregnancies offer new end po ints for an early identification of gestational hypertension and preec lampsia.