Position of the vibroacoustic stimulator does not affect fetal response.

Abstract

This study was designed to compare the fetal response to the vibroacoustic stimulation test when applied alternately over the fetal vertex or breech. Two hundred five patients with a nonreactive nonstress test after 10 minutes were prospectively randomized to receive the vibroacoustic stimulation test over the fetal vertex (n = 115) or the fetal breech (n = 90). Fetal heart rate reactivity was evaluated. Two patient subsets were evaluated for fetal movement (n = 37) and the fetal startle response (n = 20) after the vibroacoustic stimulation test. Virtually identical fetal heart rate responses and increases in fetal movement were observed after vibroacoustic stimulation over the fetal vertex or breech. The fetal startle response was uniformly observed in both groups. Vibroacoustic stimulation over the fetal breech elicits an identical short-term fetal response compared with stimulation over the fetal vertex, potentially reducing the intensity of sound exposure at the fetal ear.