Continuous intrapartum monitoring of fetal heart rate (FHR) patterns began in the 1960s in an effort to decrease birth asphyxia and cerebral palsy. Yet while continuous fetal monitoring has been shown not to decrease cerebral palsy, it continues to be used in a majority of labor suites. To help in the uniform description and assessment of FHR patterns, the National Institute of Child Health and Human Development (NICDH) issued two consensus guidelines publishing agreed definitions of FHR patterns. Terms such as late, variable, and early decelerations, variability, tachycardia, bradycardia, and tachysystole are defined. A second publication by NICDH proposes a three-category system into which FHR patterns can be divided. This chapter also includes an explanation of the fetal pathophysiologic changes that account for FHR patterns, including normal variant patterns, hypoxic, and hypercarbic findings. Potential interventions, limitations, and the challenges of FHR interpretation are also discussed. [ABSTRACT FROM AUTHOR]