Quantitative Analysis of Fetal Actocardiogram: Update

Actocardiogram (ACG): The ACG simultaneously traced FHR curve and fetal movement signals. The MHz level continuous wave (CW) ultrasound was used, of which SPTA intensity was as weak as 1 mW/cm2. The fetal movement Doppler signals obtained by 2 MHz source ultrasound was 20-50 Hz. The ultrasound detected Doppler fetal heart beat signals at the same time, of which Doppler frequency was 100 or more HZ, i.e. single ultrasonic probe detected two phenomena, FHR and fetal movements. Fetal movement Doppler signal was separated by a band-pass filter, and formed low frequency spikes, of which amplitude was parallel to that of fetal movement (Figures 1 and 2) [1]. Uterine contraction was also simultaneously recorded to prepare the CTG function.