Computerized analysis of the fetal electrocardiogram has been developed during the past 40 years. A mature system for ST analysis (STAN) has resulted from a series of laboratory and clinical studies. The current STAN system provides adjunctive information to the standard interpretation of fetal heart rate (FHR) patterns. This monograph describes the basis for the STAN methodology, including the derivation of its basic measure, the T : QRS ratio. It summarizes the supporting research and clinical trials that have led to its adoption in obstetric practice. The STAN methodology is outlined according to current fetal heart rate classification and management guidelines. Recent clinical experiences with STAN systems in Europe and the United States are discussed. Finally, future directions for this technology are listed.