Fetal response to vibratory acoustic stimulation in periods of low heart rate reactivity and low activity

The fetal response to vibratory acoustic stimulation during periods of low fetal activity and low fetal heart rate reactivity was studied in 10 healthy pregnant women at term. In each case, two periods of low reactivity were studied. Consecutive cases alternated: The vibratory acoustic stimulus was applied 10 minutes after the first nonreactive period in half of the cases; the remainder were stimulated during the second nonreactive period. The unstimulated period served as a control. After vibratory acoustic stimulation the baseline fetal heart rate, the mean number of fetal heart rate accelerations, and, the number of fetal movements were significantly increased compared with values in the control nonstimulated periods (p < 0.0001). This consistent response to vibratory acoustic stimulation may prove to be clinically useful in altering periods of low reactivity observed during nonstress testing of normal fetuses.