Phase 0: Quiescence. Most=36 weeks of gestation. Hormones=progesterone, prostacyclin
Phase 1: Preparation for labour (activation). Uterotrophins= prostaglandins, oxytocin receptor, relaxin. Uterus is changing. Stage of Braxton-Higgs contractions.
Phase 2: Active labour (stimulation). Uterotonins= oxytocin, prostaglandins. Escalates rapidly under Ferguson reflex.
Phase 3: Involution. Uterotonins=oxytocin, prostaglandins. Uterus contracts down. Large womb is closed up. Tissue remodelling.