Kazuo Maeda*
3-125, Nadamachi, Yonago, Tottoriken, 683-0835 Japan.

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© 2012 Maeda et al.;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Correspondence: * Address correspondence to this author at the 3-125, Nadamachi, Yonago, Tottoriken, 683-0835 Japan.Tel/Fax: +81-859-22-6856; E-mail:


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.

Keywords: Actocardiogram, Fetus, Heart rate, Fetal movement, Fetal behavior, Fetal monitoring, Fetal outcome.