Electronic Fetal Heart Rate Monitoring: The 5-Tier System, Third Edition reviews the practice of fetal heart rate monitoring. Beginning with a description of the anatomy of fetal circulation, placental function as a respiratory organ, and acid-base balance, it also presents normal fetal cardiovascular and cerebral metabolism. In addition, the pathophysiologic mechanisms involved in progressive fetal asphyxia are examined via a review of the seminal animal and human studies conducted in this field. Also included is a brief summary of fetal heart rate monitoring technology currently used in clinical practice and standard nomenclature for fetal heart rate characteristics. Variant fetal heart rate patterns and the underlying physiologic mechanisms are presented as well.