Transmission of noradrenaline across the human placents.

Abstract

FŒTAL bradycardia during labour is usually taken to be a sign of ‘fœtal distress’, its occurrence being interpreted as a consequence of fœtal hypoxia. Beard1 has recently considered the possibility of an endogenous humoral agent such as noradrenaline in the maternal circulation contributing to, or causing, this type of fœtal response. After injecting noradrenaline into the pregnant human subject, he noted a transitory fœtal bradycardia but was not able to decide from his results whether this effect stemmed from uterine vasoconstriction with subsequent fœtal hypoxia or from a direct action of noradrenaline on the fœtal cardiovascular system.