A 28-year-old primigravida at 39 weeks gestation presents to the labor ward with regular uterine contractions every 3–4 minutes for the past 6 hours. On examination, her cervix is 4 cm dilated, 80% effaced, and the fetal head is at −2 station. Vital signs are stable, and fetal heart rate is 140 bpm. She reports moderate pain with contractions. What stage of labor is she currently in?

Explanation

## Diagnosis: First Stage, Active Phase ### Criteria for Active Phase (First Stage) The patient meets the diagnostic criteria for the **active phase** of the first stage of labor: | Feature | Patient Finding | Active Phase Criterion | |---------|-----------------|------------------------| | Cervical dilation | 4 cm | 4–8 cm | | Cervical effacement | 80% | >50% | | Contraction frequency | Every 3–4 min | Every 2–3 min | | Station | −2 | Variable | | Duration of labor | 6 hours | Typically 2–6 hours | **Key Point:** The first stage of labor is divided into three phases based on cervical dilation: - **Latent phase:** 0–3 cm dilation (longer, less painful) - **Active phase:** 4–8 cm dilation (faster cervical change, moderate to severe pain) - **Deceleration phase:** 8–10 cm dilation (slower rate of dilation, transition to second stage) ### Clinical Correlation At 4 cm dilation with 80% effacement and regular contractions every 3–4 minutes, this patient has progressed beyond the latent phase (which typically ends at 3 cm). The active phase is characterized by an accelerated rate of cervical dilation (approximately 1.2–1.5 cm/hour in primigravidas) and more intense, regular contractions. **High-Yield:** In the active phase, the cervix dilates at a predictable rate. Arrest of dilation (no change in 2–4 hours despite adequate contractions) defines **arrest disorder**, which may indicate cephalopelvic disproportion or inadequate contractions. ### Management at This Stage Continue labor support, analgesia as needed, and monitor for progress. Augmentation with oxytocin may be considered if contractions are inadequate.