Two methods of evaluating fetal movement responses elicited by vibroacoustic stimulation-maternal perceptions and ultrasound scan observations-were compared in 58 low-risk and 35 high-risk pregnancies from 23-36 weeks' gestation. Maternal perception of vibrator-elicited fetal movement was poor compared with ultrasound scan observation. Regardless of gestational age or risk status, the mothers perceived 27-75% fewer movements than observed with ultrasound scan. In addition, maternal movement perceptions on vibrator versus no-stimulus control trials were not reliable until 29-32 weeks' gestation, with the percentage of movement responses increasing across gestation from 11 to 48%. In contrast, ultrasound scan observations of movement were reliable on vibrator compared with no-stimulus control trials from 26 weeks, with the percentage of movement responses increasing from 22% at 23-25 weeks to 94% at 35-36 weeks. We conclude that maternal perceptions of fetal movements cannot be substituted for ultrasound scan observations for accurate assessment of fetal movements during vibroacoustic stimulation testing. (Obstet Gynecol 77:889,1991)

(C) 1991 The American College of Obstetricians and Gynecologists