Abstract
Objectives. The aim was to classify fetal behavioral states by the actocardiogram (ACG).
Methods. The duration of fetal movement burst was manually measured on the ACG where fetal heart rate (FHR) and movement bursts were recorded on a single chart. The occupancy and frequency of movement bursts among five new ACG parameters were determined in the classification of four behavioral ACG states. The ACG states were compared to the 1F–4F states of Nijhuis's classification of fetal behavior. Fourteen cases of active states of normal pregnancy at 28–38 weeks of gestation and five records of decreased movement bursts were studied. The ACG movement spikes were analyzed at 26–41 weeks of pregnancy using an automated program for the diagnosis of fetal states.
Results and conclusion. No fetal movement burst was recorded in fetal resting state of ACG, where occupancy and frequency were zero. The burst was frequent, occupancy was 32.67 ± 14.76% and frequency was 0.647 ± 0.212 cycles per minute (cpm) in the active ACG states. The longest burst duration was 5 min and accompanied by transient tachycardia in highly active states. Therefore, fetal resting ACG state was comparable to 1F, active ACG state 2F and highly active ACG state 4F states. The movement bursts were sporadic in the five cases of decreased movement, where the occupancy was less than 8% and frequency was 0.2 or less cpm. The five particular cases were classified as intermediate ACG state, and they were comparable to the 3F state. Active, resting and intermediate states were also determined by automated analysis of movement spikes. From these results, fetal behavioral states would be classified by ACG with similar utility to conventional classification.