BEHAVIORAL STATE ORGANIZATION IN NORMAL HUMAN TERM FETUSES - THE RELATIONSHIP BETWEEN PERIODS OF UNDEFINED STATE AND OTHER CHARACTERISTICS OF STATE CONTROL

Repeated alteration in episodes of quiet sleep and active sleep is a b asic feature of behavioral state organization in human fetuses. When c ompared to normal fetuses, at-risk fetuses generally exhibit extended periods of no coincidence (PsNC), that is, associations between state variables that cannot be classified as a sleep state. The purpose of t his study was to determine if fetuses with extended PsNC differ in oth er state measures from fetuses with short PsNC. Fetal heart rate and f etal eye and gross body movements were collected simultaneously on 85 normal human fetuses between 37 and 41 weeks gestation for a total of 9,135 minutes (mean 108.8 +/- 12.7 minutes, range 85-130 minutes). We found that as percent PsNC increased, the frequency (r=0.464, p < 0.00 01) of state changes increased and the time spent in active sleep (r=- 0.456, p < 0.0001) and the number of fetuses entering an awake state ( chi(2)=4.26, p < 0.039) decreased. In contrast, percent PsNC was indep endent of the length of time spent in quiet sleep (r=0.070, p > 0.05). We interpret these findings as an indication that extended PsNC may b e the result of disruption of homeostatic control mechanisms during ac tive sleep.