## Stages of Labor: Clinical Progression and Definitions ### First Stage Phases #### Latent Phase - **Cervical dilatation:** 0–3 cm (or 0–4 cm in some definitions) - **Contraction pattern:** Mild, irregular, 15–30 seconds duration - **Dilatation rate:** <1.5 cm/hour - **Duration in primigravida:** ~8 hours (highly variable) #### Active Phase - **Cervical dilatation:** 4–6 cm to 8 cm - **Contraction pattern:** Stronger, more frequent (every 2–3 minutes), 40–60 seconds duration - **Dilatation rate:** ≥1.5 cm/hour in primigravidas (≥2 cm/hour in multiparas) - **Duration in primigravida:** ~4–6 hours #### Deceleration Phase - **Cervical dilatation:** 8–10 cm - **Duration:** Variable; may be brief or prolonged ### Second Stage: Descent and Delivery - **Begins:** Full cervical dilatation (10 cm) - **Ends:** Complete delivery of the fetus - **Duration in primigravida:** 30 min to 2 hours (up to 3 hours with epidural) - **Fetal station:** Assessed using −5 to +5 scale (−5 = at pelvic inlet; 0 = at level of ischial spines; +5 = at introitus) ### Third Stage: Placental Delivery - **Begins:** Immediately after fetal delivery - **Ends:** Complete expulsion of placenta AND membranes - **Duration:** Usually 5–30 minutes - **Key distinction:** Completion requires expulsion of BOTH placenta and membranes, NOT merely cord clamping/cutting **Key Point:** The third stage is complete only when the entire placenta and all membranes have been expelled from the uterus. Cutting the umbilical cord marks separation of the baby from the placenta but does NOT define the end of the third stage. **Clinical Pearl:** Retained placenta (>30 min) or retained membranes are complications of the third stage and require manual removal to prevent hemorrhage and infection. **High-Yield:** Know the dilatation rates for active phase: ≥1.5 cm/hour (primigravida) vs. ≥2 cm/hour (multipara). Slower progress suggests prolonged labor and may warrant augmentation or cesarean delivery.
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