Studies on features of fetal movement and development of human fetus with use of fetal actogram

In 167 normal fetuses at 26 to 41 weeks of gestation, features of fetal movement and fetal development were investigated with use of actocardiograph in connection with a microcomputer system. The signals of fetal movement obtained by actocardiograph were stored in a floppy disc every 250 ms for 5 minutes through an AD-converter, and were analyzed every 5 minutes with the computer to reveal 3-dimensional (3-D) histograms. The 3-D histogram of fetal movement was composed of number, amplitude and interval of the signals in 11 voltage steps between 0.05 and 0.55V. The histogram clearly indicated state of fetal behavior, being either resting or active state. Fetal movement such as rolling movement, breathing movement and hiccup could be also identified with the computer analysis. In 68 normal fetuses at 14 to 41 weeks of gestation, the cross-correlation between fetal movement and fetal heart rate (FHR) were examined with the computer analysis. Finally fetal responses to acoustic and light stimulation were evaluated with use of pure-tone generator and flashlight. Acoustic stimulation was carried out in 53 normal fetuses at 28 to 41 weeks and light stimulation was performed in 116 normal fetuses at 18 to 41 weeks of gestation. The fetal responses were evaluated with actocardiogram. As a result, 1) Frequency in active state decreased and resting state increased as gestational weeks advanced, and then the frequencies of both state remained constant after 37 weeks of gestation. Duration of resting state also increased from 26 weeks to 37 weeks. These observations may suggest that fetal behavior can be established by 37 weeks of gestation. 2) Frequency in rolling movement decreased until 37 weeks of gestation, and then the movement increased during 38-41 weeks. Frequency in breathing movement increased to 33 weeks of gestation, then it remained constant. Hiccup occurred most frequently at 30-33 weeks, and it decreased thereafter. The function in fetal respiratory movement may be accomplished by 33 weeks of gestation. 3) Positive cross-correlation between fetal movement and FHR was observed as gestational weeks advanced. The correlation coefficient increased from 14 weeks up to 41 weeks. Acceleration of FHR following fetal movement eventually occurred in fetuses at 16 weeks, but the onset of acceleration delayed than normally occurred in developed fetuses. The delay was shortened in fetuses at 24 weeks and this was comparable to the delay in developed fetuses. These results suggest that the linkage of the acceleration of FHR with fetal movement is established at 24 weeks of gestation.(ABSTRACT TRUNCATED AT 400 WORDS)