Intrapartum fetal vibratory acoustic stimulation during spontaneous and induced states of low activity and low heart rate variability.

Fetal response to vibratory acoustic stimulation (VAS) was studied in 12 healthy parturients in the active phase of labor. All fetuses were evaluated in both spontaneous and analgesia-induced states of low activity and low cardiac beat-to-beat variability. Analgesia was induced with intravenous maternal administration of meperidine, 0.