Remarkably high levels of catecholamines were found in the umbilical blood of newborn infants.1 The levels were approximately 20-fold higher after normal birth than in resting adults.2 Extremely high levels were seen after instrumental delivery and/or asphyxia. On the other hand, relatively low levels were seen after elective C-section. At about the same time Walters and Olver3 reported that the adrenaline surge in newborn lambs stimulated lung liquid absorption. We could also demonstrate that the transient tachypnoea often seen after elective C-section could be prevented by beta-adrenergic stimulation with terbutaline.4 Furthermore, infants born after C-section lacking the catecholamine surge more often suffered from hypoglycaemia and hypothermia. The activation of the noradrenergic system in the brain may be responsible for the arousal seen in newborn infants.5 Recently, we have also demonstrated that newborns are less sensitive to pain. Thus the stress of being born seems to be good for the baby.2

The catecholamine surge is probably triggered by the squeezing and squashing of the fetal head, although asphyxia could enhance the release of more catecholamines. Birth is not only associated with a surge of neurohormones, but also by the activation of genes, particularly transcription factors.5