Exercise-induced changes in uterine artery blood flow, as measured by Doppler ultrasound, in pregnant subjects.

Eleven healthy women with singleton pregnancies between 16 and 28 weeks gestation were continuously exercised, in a graded fashion, by stationary bicycle to a predetermined target heart rate. Before and within 3 minutes after exercise, uterine artery waveforms were identified from a semirecumbent position using a 3.5 MHz continuous-wave Doppler transducer coupled to an Angioscan spectrum analyzer. The ratio of peak systolic to end-diastolic frequency (A/B ratio) was utilized to assess qualitative differences in flow before and after exercise. No statistically significant changes in A/B ratios were noted. This study suggests that nonexhaustive maternal exercise does not compromise uterine artery blood flow in healthy, low-risk pregnant subjects.