Human cyclic motility: fetal-newborn continuities and newborn state differences.

The spontaneous movement of 41 healthy human newborns was analyzed for cyclic patterns during different behavioral states and also compared to similar data obtained during their last few months of gestation. Spectral analysis was used to identify and quantify the motility cycles, except in quiet sleep, for which the instantaneous frequency of the isolated movements was analyzed. Cyclic motility (CM) was common in all states, and measures of its cyclic organization were similar in the non-sleep states in spite of very large differences in the total amount of movement. During active sleep, CM was weaker and less regular than during the non-sleep states, but similar to fetal CM during the last month of gestation. Thus cyclic variation in spontaneous motor activity, a basic feature of fetal behavior, is also a nearly constant feature of newborn spontaneous movement. Fetal CM persists relatively unchanged in the newborn during active sleep, and the cyclic organization of newborn movement is independent of the level of motor output.