Effect of orthostatic stress on umbilical Doppler waveforms in normal and hypertensive pregnancies.

Abstract

Our study examined the effects of orthostatic stress and maternal hemodynamics on umbilical systolic/diastolic ratios in normal and hypertensive pregnancies. Eighteen normal and 20 hypertensive third-trimester pregnancies were examined in the left lateral recumbent, sitting, and standing positions. Measurements included umbilical systolic/diastolic ratio, maternal blood pressure, maternal cardiac output, and maternal total peripheral resistance. All patients demonstrated a fall in cardiac output and a rise in total peripheral resistance with standing. No change in systolic/diastolic ratio occurred with change to the upright position in patients with normotension. Patients with hypertension exhibited a significant increase in umbilical systolic/diastolic ratio with postural change. The increase was more marked in women who had hypertension with elevated peripheral resistance. Patients with hypertension are at increased risk of elevation of systolic/diastolic ratio with postural change; women with high-resistance hypertension may be at highest risk.