Final answer:
The best action is to assess FHT between contractions.
Step-by-step explanation:
The best action for the nurse preceptor in this situation is to instruct the nurse to assess FHT between contractions. A fetal heart rate that increases during contractions can be a sign of fetal distress, as the oxygenated blood flow to the fetus is reduced during contractions. By assessing the fetal heart tones between contractions, the nurse can determine if the heart rate returns to a baseline level, indicating a healthy circulation to the fetus.