Slow labor: the definition changed, and many clinicians still use the old one
Active labor now starts at 6 cm, not 4.
The standard most clinicians were trained on came from 1950s data suggesting the cervix should open about 1.2 cm per hour. Modern data from more than 60,000 women show labor is much slower. At the slow end of normal, first labors progress at 0.5 to 0.7 cm per hour.
US guidance changed accordingly. Active labor is now considered to begin at 6 cm. A diagnosis of arrest in active labor should not be made before 6 cm with ruptured membranes and either at least 4 hours of adequate contractions, or at least 6 hours of oxytocin with inadequate contractions and no change.
The sentence to have ready"By the current definition, have I actually met the criteria for arrest, or am I still inside the normal range?"
Where this comes from:
182. Caughey AB, Cahill AG, Guise JM, Rouse DJ. Safe prevention of the primary cesarean delivery. Obstetric Care Consensus No. 1. Obstet Gynecol. 2014;123(3):693-711. Withdrawn; replaced by ACOG Clinical Practice Guideline No. 8, Obstet Gynecol. 2024;143(1):144-162.
183. Zhang J, Landy HJ, Ware Branch D, Burkman R, Haberman S, Gregory KD, et al. Contemporary patterns of spontaneous labor with normal neonatal outcomes. Obstet Gynecol. 2010;116(6):1281-1287.
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This page is educational. It supports the conversation with your own clinicians. It is not consent to any treatment, and it cannot assess you. If you are worried about a symptom now, see urgent warning signs.