Endocrine and metabolic changes associated with periods of spontaneous hypoxia in fetal sheep.

Periods of spontaneously occurring hypoxia have been observed in fetal sheep. These were associated with increases in the fetal plasma concentration of glucose, lactate, free fatty acids, ACTH and corticosteroids (for a fetus close to term). These changes are similar to those observed during experimentally induced hypoxia. Hypoxia may be a mechanism by which plasma metabolites and ACTH are increased in fetal sheep under physiological conditions, particularly during labour.