Fetal heart rate in the second stage of labor: recording, reading, interpreting and acting

Abstract

Although central to the cardinal movements that lead to the delivery of the fetus, the second stage of labor is often neglected from a cultural and clinical viewpoint. In this phase, acquisition is more difficult, and reading and interpretation may not be the same as in the active first phase. Namely, the most relevant findings are the occurrence and depth of bradycardia and its duration. This allows the evaluation of fetal heart rate (FHR) even without cardiotocographic recording. Instead, FHR can be accurately detected using Doppler auscultation, and it is reasonable to speak of "FHR during the second stage of labor" instead of "cardiotocography in the second stage of labor." Regardless of the cause, including head compression, umbilical cord knots, loops around the fetal neck or body, and cord entanglement, the time for intervention is often so short that any intervention may be unable to prevent injury.