Vibroacoustic-induced fetal movement: two stimuli and two methods of scoring.

Abstract

To determine whether the fetal movement response elicited by vibroacoustic stimulation depends upon the vibrator and the method used to judge movement. Two methods of obtaining elicited fetal movement responses--maternal perceptions and ultrasound scan observations--were compared using two different vibroacoustic stimuli in 16 low-risk term pregnancies. Analyses of response over trials showed that the percentage of agreement between ultrasound scan observations and maternal perceptions varied (52-96%) across stimuli. The mothers perceived 64% less movement when vibrator 1 was used and 14% less movement response with vibrator 2. Analyses of average movement scores across subjects showed similar results. Vibrator 1 elicited significantly fewer maternal perceptions of fetal movement compared with ultrasound scan observation (an average of 0.8/3 compared with 2.3/3 movements per subject, respectively). For vibrator 2, there were no differences in average movement scores obtained by maternal perception and ultrasound scan observation (an average of 2.4/3 versus 2.8/3, respectively). The stimulus used in vibroacoustic stimulation testing influences the reliability of maternal movement perceptions as compared with ultrasound scan observations.