Abstract: Objective To explore the characteristic fetal movement and FHR response elicited by acoustic stimulation and whether acoustic stimulation can induce fetal sensation. Methods Ninety-four pregnant women were recruited from Woman’s hospital, Medical School, Zhejiang University. All fetuses were at term. Stimuli-evoked fetal movements and FHR responses to acoustic stimulation with five different intensities at 95,100,105,110,115dB were observed. Results ⑴The percentage of fetal movement evoked by 95dB airborne sound was 15% and was not significantly different from that of the controls. These percentages of fetal movement evoked by 100,105,110,115dB airborne sound were 89%, 83%, 83%, 95% respectively and were significantly higher than those in controls. ⑵The percentage of FHR deceleration evoked by 95dB airborne sound was 60% and significantly higher than that of control. These percentages of FHR acceleration evoked by 100,105,110 and 115dB airborne sound were 72%, 78%, 89%and 95% respectively and significantly higher than these of controls. ⑶These peak FHR amplitudes evoked by 95,100,105,110and115dB airborne sound were –4.5bpm, 12bpm, 17bpm, 14bpm and 20.5bpm respectively. Conclusion A subtle FHR deceleration and no fetal movement are evoked by 95dB airborne sound. FHR acceleration and fetal movement are evoked by 100~115dB airborne sound. It is suggested that 95dB airborne sound may induce fetal orientation reflex and 100~115dB may induce fetal defence reflex. These unconditional reflex of infant root from prenatal period.

Key words: fetal behavior, acoustic stimulation, heart rate, fetal, fetal movement