Measurement of fetal forelimb movements in the lamb in utero.

Forelimb movements in the unanesthetized fetal lamb in utero were measured by means of transit-time ultrasound in conjunction with triceps and biceps electromyographic activity. The relationships between forelimb movements and electrocortical activity, hypoxia, and spontaneous labor were studied. There was no evidence of diurnal variation. The amount of time spent moving in low-voltage electrocortical activity with rapid eye movements was significantly less than in other electrocortical states. During acute hypoxia, forelimb movements were much reduced. In active labor near term, the fetal electrocorticogram continued to cycle between high- and low-voltage activity, and the number of movements was reduced; movements were present only during uterine contractions, provided that the fetus was not in low-voltage electrocortical activity with rapid eye movements.