Maternal and umbilical cord plasma noradrenaline concentrations during labour with and without segmental extradural analgesia, and during caesarean section.

Serial measurements of maternal and umbilical cord plasma noradrenaline concentrations were obtained in 10 patients undergoing normal vaginal delivery with segmental extradural analgesia, in 10 patients undergoing normal vaginal delivery without extradural analgesia, and in 12 patients undergoing elective Caesarean section under general anaesthesia. Maternal noradrenaline concentrations increased significantly during delivery in all three groups, the peak concentrations occurring at delivery. However, the increase in the maternal noradrenaline concentration during delivery in the extradural group was lower than in the non-extradural group (P less than 0.05). Umbilical venous and arterial concentrations of noradrenaline were lower after Caesarean section than after vaginal delivery. However, extradural analgesia did not affect the fetal noradrenaline concentrations. Since noradrenaline is probably required for the adaptation of the newborn to extrauterine life, the unaltered fetal response may be beneficial.