Human fetal behavior and blood flow in term pregnancies: a review

A review is presented of the latest data on the relationship between the blood flow velocity waveform in the lower thoracic part of the fetal descending aorta, internal carotid and umbilical artery and fetal behavioral states, in particular state 1F and 2F [1], in the normal-growing and growth-retarded fetus at term. Fetal neurological development, expressed by the emergence of fetal behavior and eventually resulting in well-distinguishable fetal behavioral states, is clearly associated with specific hemodynamic adaptations. The asymmetrically growth-retarded human fetus is capable of modifying this relationship. In the analysis of blood flow velocity waveforms for clinical purposes, fetal behavioral states and fetal heart rate have to be taken into account for a proper interpretation of recorded data.