fetal heart rate (FHR), the number of heartbeats in the fetus that occur in a given unit of time. The FHR varies in cycles of fetal rest and activity and is affected by many factors, including maternal fever, uterine contractions, maternal-fetal hypotension, and many drugs. The normal FHR is between 110 beats/min and 160 beats/min. In labor the FHR is monitored with a fetoscope, an electronic fetal monitor for detecting abnormal alterations in the heart rate, especially recurrent decelerations that continue past the end of uterine contractions.
