Abstract
The purpose of electronic fetal heart rate (FHR) monitoring is the ongoing assessment of fetal oxygenation. FHR tracings are analyzed for characteristic patterns that signify specific hypoxic or nonhypoxic events. A working knowledge of fetal physiology and the fetal response to hypoxia can aid and refine clinical interpretation of FHR patterns during labor. This article reviews the fetal response to decreased oxygenation, the physiology of subsequent FHR patterns and the clinical presentation of asphyxia in the newborn.