Anaesthesia was induced with Alfathesin (60 - 70 mul/kg) in 50 healthy mothers undergoing elective Caesarean section. Anaesthesia was maintained with nitrous oxide, oxygen, muscle relaxants and controlled ventilation. The mothers were tilted laterally throughout the operation. Blood gas studies done on the mothers before induction and at delivery, revealed a mild respiratory alkalosis associated with a moderate degree of metabolic acidosis, which appeared to increase during anaesthesia. Umbilical cord blood gas analyses indicated a mild degree of fetal respiratory acidosis (mean pCO2 Uv 45,3