The effect of vibroacoustic stimulation on fetal heart rate parameters utilizing computer analysis

We examined the effect of vibroacoustic stimulation on periodic and nonperiodic fetal heart rate (FHR) parameters in fetuses not meeting Dawes-Redman criteria utilizing computerized analysis. Antepartum FHR analysis was performed using the Oxford Sonicaid System 8000 package (Oxford Sonicaid Ltd., Chichester, UK). Patients not meeting Dawes-Redman criteria for reactivity after 20 min of monitoring were recruited for the study. A 3-sec vibroacoustic stimulation (VAS) to the maternal abdomen was then performed over the fetal head. Each patient was again monitored using the System 8000. FHR parameters were compared before and after fetal VAS using the paired Student's t-test. Twenty patients met the study criteria. The average gestational age at testing was 36 weeks. Following fetal VAS, significant increases were observed in the number of fetal movements, number of accelerations, baseline FHR, overall variation, and short-term variation. No significant changes occurred in the number of decelerations. Dawes-Redman criteria were met in 16 patients after fetal VAS. In fetuses not initially meeting Dawes-Redman criteria, VAS is associated with increased long-term periodic changes in FHR, but not with changes in the number of fetal heart rate decelerations. Furthermore, by computerized analysis, VAS is also associated with increased overall and short-term FHR variability.