Fetal and maternal cardiovascular diurnal rhythms in pregnancies complicated by pre-eclampsia and intrauterine growth restriction.

OBJECTIVES

To determine whether the diurnal blood pressure profiles in pregnant women with pre-eclampsia and/or intrauterine growth restriction (IUGR) differ from those in normal pregnant controls, and, if so, to establish whether such a difference is accompanied by altered diurnal rhythms of fetal heart rate (FHR) and its variation.

METHODS

Twenty-two women in the third trimester of pregnancy with pre-eclampsia, IUGR, or both, entered the study. Eleven healthy pregnant women served as controls. Maternal systolic and diastolic blood pressures and heart rate (MHR) were determined automatically at 30-min intervals during a period of 26 h starting at 09.00. During the study period, nine 1-h recordings of FHR were made at predetermined timepoints. FHR was analyzed numerically.

RESULTS

Systolic and diastolic blood pressures and MHR showed diurnal patterns, with the highest values during the day and a trough during the night in all women. Daytime and night-time blood pressures were higher in pre-eclamptic women (p < 0.001), and the day-night difference was smaller than in controls (p < 0.001). Diurnal patterns of FHR and its variation did not differ qualitatively between the three study groups. However, FHR was affected by the maternal blood pressure profile, and all FHR parameters and their diurnal ranges were quantitatively different in IUGR fetuses (p < 0.05).

CONCLUSION

In pre-eclamptic women, there was blunting of the diurnal blood pressure profile. This altered maternal hemodynamics was associated with a similar reduction in FHR amplitude during the 26-h period but not with FHR variation. Although diurnal rhythms of FHR and its variation persisted qualitatively in the IUGR fetuses, they seemed to have been reset quantitatively, leading to a flattened diurnal pattern.