To develop a clinical device for monitoring FBM with a simplified mechanism, the multichannel pulsed Doppler device was achieved by modifying the ultrasonographic module and probe of a cardiotocograph. A new algorithm of signal processing with a highaccuracy displacement estimation technique pro· duced real-time and continuous displacement calculations. In vivo measurements demonstrated that B asic research on fetal behavior in chronic animal models as well as in human fetuses demonstrated that the mode of fetal behavior reflects fetal condition and neural function. t,3 Bio· physical profile scoring, 4 which uses fetal behavioral parameters, is a valuable method in the management of high-risk pregnancy. In the past, to clinically ob· tain changes in fetal motor activity, we have had to observe the fetus by using B-mode ultrasonography over a long time. Moreover, the quantitative assessment of the movements was difficult. Techniques have been devised to measure fetal movements, especially FBM, in the human fetus, such as A-mode ultrasonography,u B-mode imaging,7·S PLL,9.to and the special pressure transducer.n However, these methods were for research purposes and were not directly suitable for routine clinical use. A few devices are currently available for clinical use to detect fetal movements, such as the Actocardiogram developed by Maeda12 and the fetal movement detector system developed by Lindstrom and coworkers. ll These devices estimate fetal movements through the degree of modulated Doppler shift signals, but they can detect nothing more than the presence of relatively large fetal movements and they cannot quantify the type and the magnitude of movement detected; it is impossible for them to trace very small movements, such as FBM.