The effect of nifedipine on fetal umbilical artery Doppler waveforms in pregnancies complicated by hypertension.

The effect of nifedipine 5 mg administered sublingually to pregnant hypertensive patients was examined in a randomised controlled double-blind study. The effect on maternal blood pressure and the fetal umbilical artery Doppler waveform was studied for 30 minutes before and 30 minutes after administration of the drug or placebo. This dose resulted in a significant drop in maternal blood pressure 30 minutes after administration and did not result in a significant change in the Doppler umbilical artery waveform (in fetuses with normal waveforms) when compared with a control group.