Final answer:
The nurse should reassure the pregnant client that Braxton Hicks contractions are common, they do not indicate immediate labor onset, and can occur throughout the pregnancy.
Step-by-step explanation:
When a pregnant client reports experiencing irregular contractions at a regular prenatal visit, a nurse determines they are experiencing Braxton Hicks contractions. These contractions are common and may occur throughout pregnancy. They are often called false labor because they do not indicate that true labor is imminent. True labor is characterized by regular contractions that become more frequent and powerful over time and help to dilate the cervix. Braxton Hicks contractions can often be relieved with rest or hydration and do not lead to cervical dilation. Therefore, the appropriate nursing action in this scenario would be to reassure the client that these contractions are common and may occur until true labor begins.