## Second Stage of Labor: Mechanism and Timing **Key Point:** The second stage begins at FULL cervical dilatation (10 cm) and ends with delivery of the fetus. Pushing should NOT begin until the cervix is fully dilated and the woman has an urge to push. ### Phases of Fetal Descent (Cardinal Movements) 1. **Engagement** — fetal head enters the pelvic inlet 2. **Descent** — progressive movement through the pelvis 3. **Flexion** — chin approaches fetal chest 4. **Internal rotation** — head rotates to align with pelvic outlet 5. **Extension** — head extends as it passes under pubic symphysis 6. **External rotation** — shoulders rotate to align with body 7. **Expulsion** — delivery of trunk and legs **High-Yield:** The mnemonic **DIFEE** (Descent, Internal rotation, Flexion, Extension, External rotation) helps recall the cardinal movements in order of occurrence. ### Duration of Second Stage | Patient Type | Duration | |--------------|----------| | **Primigravida** | 30 min–2 hours (up to 3 hours with epidural) | | **Multipara** | 5–30 minutes (up to 2 hours with epidural) | **Clinical Pearl:** Pushing at 8 cm dilatation (before full dilation) is harmful — it causes cervical trauma, maternal exhaustion, and fetal hypoxia. Delayed pushing (passive descent) until 10 cm and urge to push is now recommended. ### Why Option 3 Is Incorrect **Warning:** This is a common misconception. Modern labor management emphasizes **delayed pushing** — waiting until the cervix is fully dilated (10 cm) and the woman has a spontaneous urge to push. Pushing at 8 cm is premature and increases morbidity.
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