The effects of intrapartum vibratory acoustic stimulation during periods of decreased fetal heart rate variability were studied in 25 healthy term fetuses. Fetal monitoring and real-time ultrasound scanning were used simultaneously to detect fetal response. Vibratory acoustic stimulation was provided by an artificial larynx generating a signal at 85 dB and 85 Hz. This stimulus was applied for 5 seconds on the maternal abdomen over the fetal head after a 20-minute period of decreased fetal heart rate variability. All fetuses reacted with an immediate fetal heart rate acceleration of at least 10 bpm (range: 10 to 35 bpm, mean +/- SD = 18.4 +/- 7.0), and 19 fetuses also had sudden fetal body movement. A deceleration of the fetal heart rate after the initial acceleration was observed in nine fetuses (range: 15 to 70 bpm, mean +/- SD = 45.5 +/- 16.5). The implications of these findings are discussed in relation to the possible use of fetal vibratory acoustic stimulation for intrapartum surveillance.
Acoustic Stimulation Female