According to the American College of Obstetricians and Gynecologists (ACOG), at what cervical dilation does the active phase of the first stage of labor typically begin?

The slides define the latent phase as extending from the onset of labour to **3 cm** dilatation, and the active phase as beginning at 4 cm and continuing to full dilatation. These are the thresholds used in this course material. **Key takeaway:** In the supplied staging scheme, latent ends at 3 cm and active begins at 4 cm.\n\n**Glossary:** **Latent phase**: the early first-stage phase before active dilatation.