During the first stage of labor, cervical dilation progresses from 0 to 10 cm. At what cervical dilation is the active phase of the first stage defined to begin?

Explanation

## Definition of Active Phase **Key Point:** The active phase of the first stage of labor begins at 4 cm cervical dilation and extends to full dilation (10 cm). ### Phases of First Stage of Labor | Phase | Cervical Dilation | Duration (Primigravida) | Characteristics | |-------|-------------------|------------------------|--| | Latent | 0–3 cm | 6–8 hours | Irregular contractions, slow dilation | | Active | 4–7 cm | 3–6 hours | Regular contractions, faster dilation (≥1.2 cm/hr) | | Deceleration | 8–10 cm | 30 min–2 hours | Slowing of dilation rate before transition | **High-Yield:** The active phase is characterized by: - Cervical dilation rate of ≥1.2 cm/hour in primigravidas - Stronger, more frequent uterine contractions (every 2–3 minutes) - Descent of fetal head begins **Clinical Pearl:** Partograph assessment and cervical examination at 4 cm dilation helps identify prolonged labor in the active phase, which is the most common indication for augmentation or intervention. **Mnemonic:** LAD = **L**atent (0–3), **A**ctive (4–7), **D**eceleration (8–10).