Computerized assessment of fetal behavioral states.

Fetal heart rate and fetal movements provide information on the fetal condition. In the near term human fetus, four behavioural states have been described based upon heart rate patterns and presence or absence of eye and body movements. For our studies concerning fetal physiology as well as the influence of maternal antiepileptic medication and the effects of intrauterine growth retardation on the fetal condition, we developed a computerized system for acquisition and storage of fetal heart rate signals and observed fetal movements. Fetal heart rate is recorded using a commercially available monitor combined with a home-made computer interface. Fetal movements are observed using two real-time ultrasound units. The observers handle keyboards to mark occurrence and duration of various types of fetal movements, and pedals to mark the visibility of the observed part of the fetal body. Keyboards and pedals are scanned by the computer. Special techniques are used to store heart rate and movement signals in an efficient way. Three experts determine fetal heart rate patterns by application of a Delphi group opinion procedure. Fetal behavioral states are identified by the computer using the results of the Delphi procedure, and performing the so-called extended automatic window procedure. This procedure identifies periods of presence and periods of absence of fetal eye and body movements, and incorporates the loss of visibility of the ultrasound images during the recording session. Fetal heart rate variability indices and distributions of fetal movements can be computed in the context of the fetal behavioral state concept.