Intrauterine Administration of L‐noradrenaline and Propanolol During the Second Trimester of Pregnancy

Summary The effect of intrauterine administration of noradrenaline and propanolol on myometrial activity during the second trimester of pregnancy was investigated. Extra‐amniotic doses of 1–2 mg. of noradrenaline given two‐hourly to 13 women increased myometrial contractility and resulted in abortion in six. Administered by the intra‐amniotic route, noradrenaline (4 mg. two‐hourly) also increased uterine activity but failed to terminate pregnancy. Propanolol, a β‐adrenergic blocking agent, was also oxytocic when instilled into the extra‐amniotic space and a termination of pregnancy with this compound is reported. It is suggested that under physiological conditions, adrenaline may exert an inhibitory action on the gravid uterus.