Arterial blood pressure (BP) and heart rate (HR) of 31 hospitalized pregnant women at low risk of hypertension were automatically monitored for 48 h at 15-min intervals. Each of the recorded 56 data series for systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and HR was chronobiologically assessed by linear-nonlinear rhythmometry. The rhythm-adjusted mean (MESOR), circadian amplitude, circadian acrophase, and best-fitting period were grouped by pregnancy trimester and further subjected to analysis of variance. BP MESOR remained unaltered, whereas HR MESOR increased significantly in middle and late pregnancy. Ultradian rhythms, with an amplitude higher than that of the circadian rhythm, were found in 25% of the SAP records in the second and third trimester. Such ultradian rhythms were not detected in the simultaneously recorded HR. Finally, the group BP and HR circadian acrophases coincided in the first trimester, but were significantly apart in mid and late pregnancy. These observations support the notion that the coordination of BP and HR rhythmicity involves different physiological mechanisms. Analysis of the individual variability in the chronobiological end points (based on the records of nine women monitored in each pregnancy trimester) revealed that only the BP MESOR was well reproducible in the course of pregnancy and may be useful in early diagnosis of gestational hypertension. Copyright (C) 1999 Elsevier Science Inc.
Bibliographical noteFunding Information:
This study was supported by the U.S. National Institutes of Health (GM-13981); National Heart, Lung and Blood Institute (HL-40650); Minnesota Medical Foundation (SMF-745-88); Bulgarian Program for the Study of the Human Brain (G-43); and the Fogarty International Center under the International Exchange Program.
- Blood pressure
- Chronobiological assessment
- Circadian rhythm
- Heart rate
- Ultradian rhythm