Final answer:
The nurse takes the action of assessing the fundus for firmness and position first after a normal vaginal delivery.
Step-by-step explanation:
The nurse would first assess the fundus for firmness and position after a normal vaginal delivery. The fundus is the top portion of the uterus, and assessing it for firmness helps determine if there is postpartum hemorrhage. Additionally, checking the position of the fundus ensures that the uterus is contracting and returning to its pre-pregnancy size.