Final answer:
The initial nursing action the nurse should take when late decels appear on the fetal monitor is to reposition the patient in the left lateral position.
Step-by-step explanation:
When late decels appear on the fetal monitor, the initial nursing action the nurse should take is to reposition the patient in the left lateral position. This position helps to relieve pressure on the vena cava, which improves blood flow and oxygenation to the baby. It can also help to alleviate compression on the fetal head and umbilical cord.