Actocardiogram is the simultaneous recording of fetal movement (FM) and fetal heart rate (FHR) with the use of a single transducer by weak ultrasound. Fetal behavioral states, fetal hiccups, nonpathologic sinusoidal FHR pattern induced by cyclic FM were reported in the use of this technique. Computer processing of FM signals enabled automatic recognition of fetal behavior. Fetal hypoxic state preceding fetal distress was diagnosed by the actocardiogram. Cross-correlation coefficient of FHR and delayed FM was high, showing a new possibility of detailed grading of mild fetal hypoxia.