Final answer:
The nurse is assessing the period between the end of one contraction and the beginning of the next when evaluating the frequency of contractions.
Step-by-step explanation:
When evaluating the frequency of contractions, the nurse assesses the period between the end of one contraction and the beginning of the next.
For example, at the beginning of labor, contractions may occur every 3-30 minutes. However, as labor progresses, contractions may occur as frequently as every 1.5-2 minutes.
This assessment is important to monitor the progress of labor and determine if labor is progressing normally.