Final answer:
The critical advice for the nurse to give the pregnant woman is to stay out of any rooms that are being renovated.
Step-by-step explanation:
The critical advice for the nurse to give the pregnant woman in order to protect the unborn child is to stay out of any rooms that are being renovated. Renovation projects can release harmful substances such as lead dust or asbestos fibers, which can pose a risk to the developing fetus. Therefore, it is important for the pregnant woman to avoid exposure to these potentially toxic materials.