Final answer:
The nurse should advise the pregnant client to get tested for bacterial vaginosis.
Step-by-step explanation:
The best action for the nurse to advise the pregnant client who is experiencing yellow-gray frothy vaginal discharge and local itching is to get tested for bacterial vaginosis.
Yellow-gray frothy vaginal discharge and local itching are symptoms commonly associated with bacterial vaginosis, which is an ain the bacteria in the vagina. Bacterial vaginosis can increase the risk of preterm birth and low birth weight, so it is important for the client to get tested and receive appropriate treatment if necessary.
Other options such as applying a heating pad, scheduling a prenatal massage, or starting a rigorous exercise routine would not address the underlying condition and would not be appropriate actions to take.