Fetal plasma ACTH (A), POMC / pro-ACTH (B), and cortisol (C) before, during and after a 10-minute period of brachiocephalic occlusion. Hatched area is period of cerebral hypoperfusion. Mean values of hormones ± SE in control (open circles, n = 14) and 3mg/kg ketamine-treated (closed circles, n = 4) fetuses. a P < 0.001 Significant increase from control 0 minute value. b P < 0.01 Significantly different from ketamine 5 minute value. * P < 0.001 Significant interaction of time × group.