The effects of maternal exercise were studied in 20 healthy women with uncomplicated pregnancies. A continuous-wave Doppler ultrasound system was used to record arterial flow velocity waveforms from the ascending vasculature downstream from the uterine artery. The fetal heart rate was monitored with a Doppler ultrasound cardiotocograph. No significant change was found in the uterine blood flow velocity waveform post-exercise, as expressed by the pulsatility index, suggesting absence of change in the uterine vascular bed resistance. The fetal heart rate significantly increased after exercise.