What characterizes the active phase of labor?

The active phase of labor is defined by the significant progression of cervical dilation, specifically from 6 cm to 10 cm, which is considered full dilation. This phase is marked by more intense and regular contractions, indicating that the body is effectively moving toward delivery. As cervical dilation increases during this phase, it becomes a crucial indicator of the labor progression, with the goal being the transition to the pushing phase once complete dilation is achieved.

The other options either describe phases of labor outside the active stage or do not accurately reflect the expected rates or measurements during active labor. For instance, dilation rates of 1-2 cm per hour typically describe the latent phase rather than the active phase, and dilation from 0 to 6 cm encompasses the earlier part of labor, not the active phase. Additionally, a dilation rate of 3-4 cm per hour is unusually rapid compared to typical definitions and clinical observations for this phase.