Ethics is an essential dimension of maternal critical care. This chapter commences with a definition of ethics, medical ethics, and the fundamental ethical principles of medical ethics: beneficence and respect for autonomy. The ethical concept of the fetus as a patient is essential to maternal critical care in all cultural and national settings. Maternal critical care is ethically more complex when the fetus is a patient. After viability, discontinuation of critical care management should include delivery of the fetal patient. Preventive ethics uses the informed consent process to anticipate and prevent ethical conflict between patients and their physicians. The physician's role is to explain to the pregnant patient before critical care is initiated its nature as a trial of management. The advantage of the durable power of attorney for healthcare is that it applies only when the patient has lost decision-making capacity, as judged by his or her physician.