Effect of maternal exercise with graded treadmill on fetal heart rate

: The effect of maternal exercise on the fetal and maternal heart rate was studied in 10 normal pregnant women in their third trimester. They participated in 15 minute graded treadmill exercise. Fetal heart rate (FHR), uterine contraction, maternal blood pressure, electrocardiogram, and oxygen consumption were monitored, before, during, and after exercise. FHR could be monitored in 7 women. Maternal maximal heart rate ranged from 143 to 168 bpm which approximated 61% to 84% training intensity. FHR showed a significant rise in 4 women during exercise. Of four cases which showed more than 70% training intensity, 3 demonstrated fetal tachycardia over 160 bpm and one demonstrated fetal bradycardia under 120 bpm. The baseline fetal heart rate remained from 120 bpm to 160 bpm in cases under 70% training intensity. There was no pathological deceleration and the variability was preserved in all cases. It is suggested that maternal exercise intensity should be less than 70% of the patient's maximal capacity, which approximates maternal heart rate of about 150 bpm.