Final answer:
Immediately following the birth of the placenta, the nurse should examine it to ensure it is complete to prevent postpartum complications. Post-delivery, monitoring the mother and initiating breastfeeding are also important steps.
Step-by-step explanation:
The nurse's action immediately following the birth of the placenta is to examine the placenta for completeness. This is essential because any fragments of the placenta left in the uterus can lead to serious complications such as postpartum hemorrhage. After ensuring the placenta and membranes are intact, the nurse will proceed with further postpartum care, which includes monitoring uterine contractions as they facilitate the return of the uterus to its pre-pregnancy size, a process called involution. Additional care also includes observing the mother for any signs of complications and promoting the initiation of breastfeeding, which helps in the involution process.