Effect of reducing uteroplacental blood flow on movements and on electrocortical activity of fetal sheep.

Eight chronically instrumented fetal sheep were asphyxiated for 1 h by partial occlusion of the uterine blood supply. Fetal movements, as reflected by phasic activity in the nuchal electromyogram, decreased during the period of asphyxia. Tonic activity also decreased. The proportion of time spent in high-voltage electrocortical activity increased. Following release of the occlusion movements returned rapidly to the level present during the control period. The distribution of electrocortical activity patterns during the recovery period was similar to that during the control period.