CIRCADIAN BLOOD-PRESSURE VARIABILITY IN HEALTHY AND COMPLICATED PREGNANCIES

With the aim to describe the circadian pattern of noninvasive ambulato rily monitored blood pressure during the trimesters of pregnancy in cl inically healthy women as well as in pregnant women who developed gest ational hypertension or preeclampsia, we analyzed 759 blood pressure s eries sampled by ambulatory monitoring for about 48 hours every 4 week s after the first obstetric visit in 71 women with uncomplicated pregn ancies, 28 with gestational hypertension, and 14 with preeclampsia. Th e circadian pattern of blood pressure variation for each group (compli cated versus uncomplicated pregnancies) and trimester of gestation was established by linear least-squares methods. A highly statistically c ircadian pattern is demonstrated for systolic and diastolic blood pres sure for both groups of pregnant women in all trimesters (P < .001 in all cases). Blood pressure decreases from the first trimester to the s econd and rises again in the third for healthy pregnant women. For wom en who developed gestational hypertension or preeclampsia, blood press ure is stable during the first half of pregnancy and then continuously increases until delivery. The differences in circadian rhythm-adjuste d mean between complicated and uncomplicated pregnancies are highly st atistically significant in all trimesters (always P < .001). This stud y confirms and extends to ambulatory everyday life conditions the pred ictable circadian variability in blood pressure during gestation. The differences in blood pressure between healthy and complicated pregnanc ies can be observed as early as the first trimester of pregnancy. Thos e differences are found when both systolic and diastolic blood pressur es for women with a later diagnosis of gestational hypertension or pre eclampsia are well within the accepted normal physiological range of b lood pressure variability.