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Mechanism of labour (OA)

The cardinal movements.

Source: Textbooks

Movements

  1. Engagement — biparietal diameter through inlet, sagittal suture transverse/oblique.
  2. Descent — throughout labour.
  3. Flexion — occipitofrontal 11.5 → suboccipitobregmatic 9.5 cm.
  4. Internal rotation — occiput turns 1/8 to OA at the pelvic floor.
  5. Extension — crowning; occiput pivots under symphysis.
  6. Restitution — head turns back 1/8.
  7. External rotation — shoulders turn into AP diameter.
  8. Expulsion — anterior shoulder, posterior shoulder, body.
A summary for trained clinicians. Always check the full guideline, the patient in front of you and your hospital's protocol. Spotted an error? Tell us.