Final answer:
The 40-year-old gravida 2 patient is the highest priority for nutritional instruction due to the increased risks associated with advanced maternal age.
Step-by-step explanation:
When preparing nutritional instruction, the nurse would consider the 40-year-old gravida 2 patient as the highest priority. This is because the risks associated with pregnancy, such as the increased chance of fetal genetic abnormalities like trisomy 21, rise significantly with maternal age, particularly after 35 years old. Therefore, careful consideration of nutritional needs is essential to support a healthy pregnancy and reduce potential complications. Additional support and guidance through genetic counseling may also be beneficial for this patient because of her age.