Blood pressure patterns in normal pregnancy, gestational hypertension, andpreeclampsia

With the aim to describe the daily pattern of blood pressure during the tri mesters of pregnancy in clinically healthy women as well as in pregnant wom en who developed gestational hypertension or preeclampsia, we analyzed 1494 blood pressure series systematically sampled by ambulatory monitoring for 48 hours every 4 weeks after the first obstetric visit in 124 women with un complicated pregnancies, 55 with gestational hypertension, and 23 with a fi nal diagnosis of preoclampsia. The circadian pattern of blood pressure vari ation for each group and trimester of gestation was established by populati on multiple-component analysis. A highly statistically significant circadia n pattern represented by a linear model that includes components with perio ds of 24 and 12 hours is demonstrated for systolic and diastolic blood pres sure for all groups of pregnant women in all trimesters (P<0.001 in all cas es). The differences in circadian rhythm-adjusted mean between complicated and uncomplicated pregnancies are highly statistically significant in all t rimesters (always P<0.001). There is also a statistically significant diffe rence in circadian amplitude (extent of daily change) of blood pressure bet ween healthy and complicated pregnancies in all trimesters (always P<0.004) . Results further indicate similar circadian characteristics between women who later developed gestational hypertension or preeclampsia in the first t rimester of pregnancy. The difference between these 2 groups in circadian m ean is statistically significant in the second trimester for systolic (P=0. 022) but not for diastolic blood pressure (P=0.986). In the third trimester , the difference in circadian mean is highly statistically significant for both variables (P<0.001). The differences in blood pressure between healthy and complicated pregnancies can be observed as early as in the first trime ster of pregnancy. Those highly significant differences are found when both systolic and diastolic blood pressure for women with a later diagnosis of gestational hypertension or preeclampsia are well within the accepted norma l physiological range of blood pressure variability. These differing change s in the circadian pattern of blood pressure with advancing gestational age between healthy and complicated pregnancies offer new end points that may lead to an early identification of hypertensive complications in pregnancy as well as to the establishment of prophylactic intervention.