In order to test the effects of maternal exercise in late gestation on fetal biophysical activities as measured by fetal breathing, shoulder movement, and kick response, these parameters were monitored by ultrasound in ten healthy pregnant women at 35 weeks of gestation before and after 20 minutes of aerobic dance and before and after 20 minutes of rest. A randomized crossover design between exercise (sequence A) and rest (sequence B) that used each pregnant woman as her own control was used in this study. Cumulative means for each fetal activity were compared. Results indicated a significant decrease in fetal breathing after maternal exercise and no significant change in shoulder movements or kick response.