Effect of low-sodium diet on uteroplacental circulation

Objective: To study the influence of chronic dietary sodium restriction on uteroplacental circulation.Methods: In a randomized trial, Doppler flow velocity waveforms of the uterine and umbilical artery were studied at monthly intervals during pregnancy in 59 women on a low-sodium diet and in 68 controls.Results: Pulsatility index (PI), resistance index (RI), and A/B ratio of the uterine artery were significantly lower during sodium restriction, whereas PI, RI, and A/B ratio of the umbilical artery were significantly higher.Conclusions: The lower resistance indices of the uterine artery during sodium restriction might reflect an increase in pulse pressure/impedance ratio as a result of activation of the renin-angiotensin system. The increase in umbilical artery resistance indices supports the hypothesis that fetal circulation might be altered by chronic dietary sodium restriction.