MORPHOLOGY OF ACTIVE SLEEP - QUIET SLEEP TRANSITIONS IN NORMAL HUMAN TERM FETUSES

Periods of no coincidence (PsNC) among state variables appear to be mo re predictive of neurobehavioral outcome than the amount of time spent in any particular behavioral state. It has recently been suggested th at analysis of the ordering of state variables during a state transiti on may provide results equivalent to full state analysis. If this were the case. then there ought to be a relationship between the duration of PsNC and fetal heart rate (FHR)-fetal eve movement (FEM) sequencing at the time of a state change. To test this hypothesis, we compared f ull stare analysis with analysis of individual state transitions for 5 2 normal human fetuses between 38 and 42 weeks of gestation. For the s tudy population as a whole, FHR was the first variable to change in 62 (77%) of 81 1F --> 2F transitions and FEM was the first variable to c hange in 50 (63%) of 79 2F --> 1F transitions (chi(2) = 67.9. p < 0.00 1). Ordering of FHR and FEM at the time of a stare change was reversed in 8 (67%) of 12 fetuses with PsNC greater than or equal to 15% and i n only 6 (15%) of 40 fetuses with PsNC < 15% (chi(2) = 12.5, p < 0.001 ). We conclude that fetuses who exhibit poor state organization more o ften display a FHR-FEM sequence at the rime of a stare transition whic h is opposite that of fetuses with consierably better state control. H owever. since only one-third of fetuses with reversed FHR-FEM sequenci ng acutally exhibited more than one such episode, it is unlikely that isolated analysis of state transitions will provide a reliable measure of behavioral state organization in the individual fetus.