Reversed circadian blood pressure rhythm preserves fetal growth in preeclamptic pregnancy

To determine the clinical trait of hypertension in pregnant women with a reversed circadian blood pressure (BP) rhythm.

24-h BP monitoring was performed in 56 hypertensive pregnant women, of whom 12 had a reversed systolic BP (SBP) rhythm (day/night mean BP ratio < 1.0). Clinical data, ultrasound fetometry and umbilical artery velocimetry were compared to that in women with a normal rhythm. Statistical analyses were performed with simple linear regression, Mann-Whitney U test, analysis of variance, contingency table analysis and Fisher's test. A two-tailed P value of < 0.05 was considered significant.

In the reversed SBP group, the nighttime BP, fetal weight, albuminuria and S-urate were higher, and the BP variations smaller. The birthweight correlated negatively to the SBP day/night ratio. Higher SBP day/night ratios and larger BP variations were associated with an increased vascular resistance in the umbilical artery and an impaired growth.

A reversed SBP rhythm was associated with a more severe degree of preeclampsia, but also with a smaller BP variation, maintenance of fetal growth, and higher birthweight. A sustained high nighttime BP preserved fetal growth. These novel observations challenge the opinion that a reversed circadian BP rhythm is merely an ominous sign.