ABSTRACT
From the first description made by Dawes and associates two decades ago of behavioral states in the fetus using a sheep model (Dawes, Fox, Leduc, Liggins, & Richards, 1970), there has been an increasing interest in this subject. In particular, the refinement of ultrasound methods and their application to the human fetus have allowed a noninvasive assessment of human fetal movements (Birnholz, Stephens, & Faria, 1978; Bots, Nijhuis, Martin, & Prechtl, 1981) and heart rate patterns (Evertson, Gauthier, Schifrin, & Paul, 1979). This technical advance opened up a new field of behavioral studies, confirming the results obtained from animal models. Indeed, Timor-Tritsch, Dierker, Hertz, Deagan, and Rosen (1978) showed that in the human fetus near term heart rate and body movements are clustered in episodes resembling quiet and active phases of animal behavior. Nijhuis, Prechtl, Martin, and Bots (1982) found evidence of stable and
recurring associations between heart rate, body movements, and fetal eye movements, similar to those used by Prechtl (1974) to identify behavioral states in the newborn. These associations develop from the second trimester of pregnancy and become particularly evident from 36 weeks of gestation onward.
