Final answer:
Nurses should be aware that respiratory function returns to nonpregnant levels by 6 to 8 weeks after birth.
Step-by-step explanation:
Nurses should be aware that the cardiovascular system undergoes several changes and developments after childbirth. The correct option is B. Respiratory function returns to nonpregnant levels by 6 to 8 weeks after birth.
During pregnancy, blood volume increases to manage the demands of the fetus. The pulse and blood pressure also rise moderately. After childbirth, these values gradually return to normal. However, it takes about 6 to 8 weeks for respiratory function to fully recover to nonpregnant levels.
Therefore, nurses should be aware of these changes and monitor the respiratory function of postpartum women as they recover after childbirth.