Final answer:
The phase of labor where the patient's cervix dilates from 4-8 cm is the dilation stage of labor, which is part of the first stage of labor. This stage typically lasts 6-12 hours, but the duration can vary.
Step-by-step explanation:
The phase of labor where the patient's cervix dilates from 4-8 cm is the dilation stage of labor, which is part of the first stage of labor. During this stage, uterine contractions cause the cervical canal to widen until it reaches about 10 cm in diameter, allowing the baby's head to pass through. This stage typically lasts 6-12 hours, but the duration can vary.