Final answer:
When Mrs. Lopez refuses HIV testing during pregnancy, the appropriate action is to respect her decision, while continuing, to provide education and support regarding the importance and benefits of testing.
Step-by-step explanation:
The ethical and professional response when a patient like Mrs. Lopez refuses HIV testing during pregnancy is to respect her decision and continue with prenatal care. This approach aligns with respecting patient autonomy and informed consent. However, the healthcare provider should still continue to educate and offer support for HIV testing, emphasizing the importance of early detection, the availability of antiretroviral medications to reduce mother-to-child transmission, and how these measures can improve health outcomes for both the patient and the infant.