Fetal sympatho-adrenal mediated metabolic responses to parturition.

Plasma cortisol and noradrenaline were measured in 15 mothers and babies following vaginal delivery and in 17 following elective caesarean section and related to blood concentration of glucose and glycerol. Significant elevations in umbilical artery cortisol and noradrenaline concentration were found in the vaginal delivery group. Blood glucose and glycerol concentrations were significantly higher in the vaginal delivery group for maternal venous, umbilical artery and vein samples. However, when allowances were made for placental transfer of these substances, little evidence was found to support sympatho-adrenal mediated mobilization of glycerol and glucose in the fetus. The possible explanation for the apparent dissociation between marked sympatho-adrenal activity and metabolic responsiveness during parturition in the fetus is discussed.