The physiology of fetal heart rate patterns and perinatal asphyxia

The purpose of electronic fetal heart rate (FHR) monitoring is the ongoing assessment of fetal oxygenation. FHR tracings are analyzed for characterist ic patterns that signify specific hypoxic or nonhypoxic events. A working k nowledge of fetal physiology and the fetal response to hypoxia can aid and refine clinical interpretation of FUR patterns during labor. This article r eviews the fetal response to decreased oxygenation, the physiology of subse quent FHR patterns and the clinical presentation of asphyxia in the newborn .