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Intrapartum fetal heart rate assessment

Author
Bruce K Young, MD
Section Editor
Charles J Lockwood, MD, MHCM
Deputy Editor
Vanessa A Barss, MD, FACOG

INTRODUCTION

The rationale for monitoring the fetal heart rate (FHR) during labor is that FHR patterns are indirect markers of the fetal cardiac and central nervous system response to blood volume changes, acidemia, and hypoxemia, since the brain modulates heart rate. Virtually all obstetric societies advise monitoring the FHR during labor. This position is largely based upon expert opinion and medicolegal precedent; neither continuous electronic fetal monitoring nor intermittent auscultation has been proven beneficial in low risk pregnancies.

Intrapartum fetal monitoring will be discussed here. Fetal cardiac physiology, FHR patterns, and antepartum FHR monitoring (nonstress test, contraction stress test) are reviewed separately. (See "Nonstress test and contraction stress test".)

GOALS AND EFFECTIVENESS OF INTRAPARTUM FHR MONITORING

The primary goal of intrapartum FHR monitoring is to identify hypoxemic and acidotic fetuses in whom timely intervention will prevent death. A secondary goal, based on expert opinion, is to avoid fetal neurologic injury. There is some evidence that intrapartum fetal monitoring achieves a reduction in intrapartum death [1], but no evidence of a reduction in long-term neurologic impairment.

The two most commonly used modalities for intrapartum FHR monitoring are continuous electronic FHR monitoring and intermittent auscultation. In initial FHR monitoring studies that compared intermittent auscultation with no monitoring, intermittent auscultation was not associated with a decrease in perinatal mortality or neurologic disability despite an increased incidence of operative intervention [2,3]. No trials have compared continuous electronic fetal monitoring with no monitoring.

For both low and high risk pregnancies, there is no convincing evidence that continuous electronic FHR monitoring performs better than intermittent auscultation and consistent evidence that electronic fetal monitoring has a high false positive rate for predicting adverse outcomes [4-6]. In a 2013 systematic review that compared continuous electronic FHR monitoring with intermittent auscultation (13 randomized trials, >37,000 low and high risk pregnancies), no significant differences between techniques were noted for the following outcomes [4]:

                        

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Literature review current through: Jul 2015. | This topic last updated: Aug 17, 2015.
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