Final answer:
The nurse's most appropriate response is that the baby will need to be corrected for prematurity and will reach developmental milestones based on the postconceptional age.
Step-by-step explanation:
The nurse's most appropriate response to the mother's question is:
'Your baby will need to be corrected for prematurity. Your baby is currently 40 weeks of postconceptional age and can be expected to be doing what a 40-week-old infant would be doing.'
Developmental milestones are typically based on the postconceptional age rather than the actual age of the infant. Premature infants may need some extra time to reach their developmental milestones compared to infants born at term.