Oxytocin

• Induction & augmentation of labour
• Active management of 3rd stage
• Prevention & treatment of postpartum haemorrhage (PPH)

Binds uterine OT receptors → ↑ intracellular Ca²⁺ → rhythmic myometrial contraction. Receptor density rises near term.

• W — Water intoxication (ADH-like, hyponatraemia)
• A — Atony rebound if stopped abruptly
• T — Tachysystole / fetal distress
• E — Emergency PPH dose: 5 IU slow IV
• R — Rupture (prior CS — caution)

Induction

Start 1–2 mU/min, ↑ q30 min, max 32 mU/min

3rd stage (vaginal)

10 IU IM after delivery of anterior shoulder

Caesarean

5 IU slow IV + 40 IU in 500 mL infusion

PPH

5 IU slow IV, then 40 IU/500 mL infusion

• AbsoluteMechanical obstruction to delivery
• AbsoluteHypertonic uterine activity, fetal distress
• CautionPrevious classical CS / uterine rupture risk

• Tachysystole, uterine rupture
• Hypotension & tachycardia (bolus)
• Water intoxication with prolonged high-dose infusions
• Nausea, vomiting

• • Excess dose → fetal hypoxia from tachysystole.
• • Use lowest effective dose; titrate to 3–4 contractions/10 min.

• Prostaglandins

  Avoid

  Tachysystole — give ≥6 h after vaginal PG

• Volatile anaesthetics

  Caution

  ↓ uterotonic effect

• Carbetocin / Ergometrine

  OK

  Sequential use OK for refractory PPH

• 💡 Never bolus undiluted >5 IU — risk of profound hypotension.
• 💡 Stop infusion if >5 contractions/10 min or non-reassuring CTG.