Informed consent is a cornerstone and routine component of the ethical practice of modern medicine. Its full theoretical application to specific clinical situations, however, presents a number of ethical dilemmas for health care providers. Obstetric anesthesia, in panicular, presents many unique challenges to the process of informed consent. In this review, the ethical background to the doctrine of informed consent within the context of "principlism" is explored and critiqued. The application of principlism to actual clinical situations, the limitations of principlism in the peculiarities of the patient-physician encounter, as well as possible alternative models of ethical discourse is discussed. The process of informed consent can be broken down into seven elements: Threshold elements or preconditions, which include 1) decision-making capacity or competency of the patient, 2) freedom or voluntariness in decision-making, including absence of over-riding legal or state interests; informational elements, including 3) adequate disclosure of material information, 4) recommendation, and 5) an understanding of the above; consent elements, which include 6) decision by the patient in favor of a plan and 7) authorization of that plan. Each of these elements is discussed in turn, and their implications, especially for the anesthesiologist and the obstetric patient, are addressed. (C) 2003 by Elsevier Science Inc.