Aims: To objectively study fetal movements, clarify fetal behavior, identify false positive fetal heart rate
(FHR), estimate fetal outcome, and study fetal response to external stimuli, using an actocardiogram (ACG).
Methods: The ACG is a chart record that simultaneously traces FHR and fetal movements by continuous wave (CW)
ultrasonic Doppler signals of fetal heart beats and movements using a single probe. In addition, uterine contraction is
recorded in clinical models.
Results: Signals from fetal movements are clustered to form bursts and characterized by 5 indices of mean duration,
occupancy, frequency, ratio of duration of FHR acceleration to movement bursts (A/B ratio), and the ratio of acceleration
count to the bursts; fetal behavior was classified into resting, active, hyperactive and intermediate states; non-reactive
FHR was differentiated from fetal resting FHR; sinusoidal FHR was separated from benign physiologic one; and sinus
bradycardia was separated from hypoxia. Interval of fetal hiccups was 2 sec, and hiccups lasted for 20 minutes or more
and tended to repeat in a day. The severity ranking of fetal central nervous system lesion and fetal disorder outcome were
assessed using the A/B ratio. The correlation coefficient of FHR and movement increased if the movement delayed.
A fetus responded to sound light stimulation in ACG; fetal sensitivity increased in late pregnancy.
Conclusion: The controversial obtained used a cardiotocogram were resolved using the ACG. It opened new objective
fields in perinatal medicine.