Final answer:
The nurse should turn the mother on her left side, administer O2 NC, and start an IVC as the first action when assessing a FHR of 59 beats/min during labor.
Step-by-step explanation:
The nurse should turn the mother on her left side, administer O2 NC, and start an IVC as the first action when assessing a fetal heart rate (FHR) of 59 beats/min during labor. Turning the mother on her left side helps improve blood supply to the fetus and can improve the FHR. Administering oxygen can also help improve oxygenation to the fetus. Starting an IVC can provide fluids and medications as needed.