Oxytocin

How it works

It binds uterine oxytocin receptors to increase the frequency and force of myometrial contractions, with receptor sensitivity rising towards term.

Prescribing in practice

• Excessive dosing or infusion rate can cause uterine hyperstimulation with fetal distress or uterine rupture, so labour induction/augmentation must be titrated against contractions and continuous fetal monitoring.
• Prolonged high-dose infusion with large volumes of electrolyte-free fluid can cause water intoxication and hyponatraemia owing to its antidiuretic effect.
• Rapid intravenous bolus can cause hypotension, tachycardia, and arrhythmia, so it is given by slow injection or controlled infusion.

Monitoring

Monitor uterine activity and continuous fetal heart rate during labour, together with maternal blood pressure, pulse, and fluid balance.

Counselling the patient

• Explain to the woman that this medicine strengthens contractions to help labour or to reduce bleeding after delivery.
• The infusion is closely controlled and the baby's heart rate is monitored throughout.
• Tell the team if contractions feel excessively strong or unrelenting.

Evidence & guidelines

A cornerstone of NICE-endorsed labour management and active management of the third stage of labour to reduce postpartum haemorrhage.