Behavioural States and Blood Flow Changes in the Human Fetus

In the human fetus behavioural states were studied from fetal heart rate recordings alone (de Haan 1979; van Geyn et al. 1980), and in conjunction with body movements (Timor-Tritsch et al. 1978; Natale 1985), resulting in the description of quiet and activity phases. The observations did not provide conclusive proof of the presence of true behavioural states in the human fetus since both fetal heart rate and fetal heart rate variability are affected by fetal motility (Wheeler and Guerard 1974). Nijhuis et al. (1982) stated that the presence of behavioural states can only be established following fulfillment of a number of criteria: (a) particular conditions of several variables must recur in specific, fixed combinations; (b) these combinations must be temporally stable; (c) there should be clear transitions between states.