Final answer:
The patient is in the first stage of labor because her cervix is 9 cm dilated. The first stage involves the gradual thinning and dilation of the cervix until it reaches about 10 cm. This is followed by the second stage, where the baby is expelled from the uterus, and the third stage, which involves the delivery of the placenta.
Step-by-step explanation:
The nurse is caring for a patient in labor whose cervix is 9 cm dilated. This indicates that the patient is in the first stage of labor. During the first stage of labor, the cervix gradually thins and dilates until it reaches a dilation of about 10 cm. Once the cervix is fully dilated, the second stage of labor begins, which involves the expulsion of the baby from the uterus. The third stage of labor is the passage of the placenta after the baby has been born.