Physiologic variability and fetal electrocortical activity.

The relationship between fetal electrocortical activity and multiple fetal parameters was examined in chronically instrumented fetal lambs. Consistent small but significant changes in fetal heart rate, mean arterial pressure, umbilical blood flow, and the cerebral uptake of glucose relative to oxygen were observed as fetal electrocortical activity cyclically shifted between high-voltage slow activity and low-voltage fast activity. Cardiovascular parameters were higher and the cerebral uptake of glucose relative to oxygen was lower during high-voltage slow activity than during low-voltage fast activity. The implication of these observations is discussed.