An attempt to quantify characteristics of behavioral states.

In order to describe fetal behavior in detail, 44 pregnant women were examined longitudinally between 34/0 to 42/0 gestational weeks; the traces of 38 fetuses were included for further analysis. We used two ultrasound scanners and an actocardiography and registered the number and duration of fetal head, trunk, limb, breathing, and eye movements (FEM) as well as the fetal heart rate (FHR). Data were recorded on polygraphic tracings and analyzed off-line via a 1-minute moving window. Percentile ranges were calculated throughout the observation period. Four primary behavioral states were analyzed according to Nijhuis et al. but state 3F could be neglected in our data. FHR variability, slow and rapid FEM, and the number of movements were most significant in differentiating between states 1F, 2F, and 4F. By considering percentile values of single parameters, the differentiation of states, a computer analysis, and the recognition of compromised fetuses might be facilitated.