Active phase labor arrest: revisiting the 2-hour minimum

Area of Science:

• Obstetrics
• Maternal-Fetal Medicine
• Labor and Delivery

Background:

• Oxytocin is frequently used to augment labor.
• Defining labor arrest criteria is crucial for appropriate intervention, including cesarean delivery.
• Previous studies suggest current criteria may be too strict.

Purpose of the Study:

• To collect contemporary data on uterine activity and labor progress during oxytocin augmentation.
• To evaluate if a 2-hour labor arrest with at least 200 Montevideo units warrants cesarean delivery.

Main Methods:

• A standardized protocol was used for 501 women with abnormally progressing labor, involving oxytocin and intrauterine pressure monitoring.
• Uterine activity was maintained at ≥200 Montevideo units for ≥4 hours before considering cesarean for arrest.
• Maternal and neonatal outcomes were assessed.

Main Results:

• Median cervical dilation rates were 1.4 cm/hr for nulliparas and 1.8 cm/hr for parous women during augmentation.
• 38 women had labor arrest >2 hours despite ≥200 Montevideo units; 61% achieved vaginal delivery.
• Infection rates were 26% for these 38 women; no serious neonatal complications occurred.

Conclusions:

• Oxytocin-augmented labor demonstrates slower progress compared to spontaneous labor.
• Current criteria for labor arrest (2 hours with ≥200 Montevideo units) are not sufficiently rigorous to justify cesarean delivery.
• Further research is needed to refine labor arrest guidelines.