A longitudinal study of resting peripheral blood flow in normal pregnancy and pregnancies complicated by chronic hypertension and pre-eclampsia

Objectives: To investigate the hypothesis that reduced resting tissue blood flow precedes the clinical onset of pre-eclampsia in women at risk of the disease. Methods: We used venous occlusion plethysmography to compare resti ng calf muscle blood flow in 18 normal pregnant controls, 18 pregnant women with chronic hypertension, and 23 pregnant women at increased risk of deve loping pre-eclampsia. Calf blood flow was measured at 16, 20, 24, 28, 32 an d 36 weeks of gestation. Results: Blood flow increased with gestation in no rmal pregnancy (P=0.004) and chronic hypertension (P=0.006), but not in the 'at risk' women who did not develop pre-eclampsia (P=0.36). In contrast, b lood flow decreased significantly in eight out of the 23 women 'at risk', w ho developed pre-eclampsia (P<0.00001, ANOVA). The decrease in flow precede d the clinical diagnosis of the pie-eclampsia by several weeks. Moreover, a significant inverse correlation was observed between resting blood flow an d plasma uric acid concentrations (r=-0.86, P=0.03) in the women that devel oped pre-eclampsia. Conclusions: We have shown that reduced resting blood f low precedes the clinical onset of pre-eclampsia independently of hypertens ion per se. These findings support the notion that impaired tissue blood fl ow may be involved at an early stage in the pathophysiology of the disease. (C) 2001 Elsevier Science B.V. All rights reserved.