Back to Search Results

3/1/2014

Fetal Heart Rate Baseline Abnormalities: Bradycardia

Author: Adam Sandlin, MD and Paul Wendel, MD

Registered users can also download a PDF or listen to a podcast of this Pearl.
Log in now, or create a free account to access bonus Pearls features.

Editor: Paul Wendel, MD

Editor:  Elizabeth Ferries-Rowe, MD

 

Fetal bradycardia is defined as a baseline fetal heart rate less than 110 beats per minute for at least 10 minutes. Evaluation and management may differ for antenatal and intrapartum fetal bradycardia and depends on gestational age. Fetal heart rate variability provides further information regarding the implications of bradycardia for fetal status.  The most common causes of intrapartum bradycardia include poor uterine perfusion, maternal hypotension (e.g. after epidural placement), umbilical cord prolapse or occlusion, rapid fetal descent, tachysystole, placental abruption, or uterine rupture. Antepartum bradycardia may also be due to congenital fetal heart abnormalities or conduction defects like congenital heart block. Moderate fetal heart rate variability is typically reassuring. Minimal fetal heart rate variability can be associated with normal fetal sleep cycles and maternal medication (e.g. opioids, magnesium sulfate). More worrisome causes of reduced variability include decreased fetal oxygenation and fetal neurologic abnormalities like anencephaly. 

Management of antenatal fetal bradycardia will depend on gestational age, underlying cause, and overall clinical status of the patient and fetus. When persistent fetal bradycardia with minimal variability is detected remote from term, sonographic examination to assess for structural anomalies and growth restriction should be performed. The use of the M mode for the initial evaluation is also advised. If a cardiac defect or conduction abnormality is suspected, then a fetal echocardiogram is indicated. Maternal laboratory evaluation for collagen vascular disease, specifically SS-A and SS-B antibodies, should be performed if fetal congenital heart block is suspected.  Umbilical artery Doppler studies are recommended if fetal growth restriction is present, and antenatal steroids may be warranted if there is likelihood for preterm delivery.  Antenatal surveillance is recommended in the third trimester.

Intrapartum fetal bradycardia in the context of a previously normal baseline in labor, particularly when combined with absent or minimal fetal heart rate variability, needs immediate evaluation to identify and correct the underlying cause. Intrauterine resuscitative measures should be initiated, including maternal lateral positioning, maternal oxygen administration, and intravenous fluid bolus administration. If these measures do not resolve bradycardia, especially with absent or minimal variability, digital scalp or vibroacoustic stimulation should be performed and the fetal heart rate monitored for an appropriate response.  According to ACOG, if bradycardia with minimal or absent variability or prolonged decelerations or both do not resolve, then prompt delivery is recommended.

 

Further reading:

American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 106: Intrapartum fetal heart rate monitoring: nomenclature, interpretation, and general management principles. Obstet Gynecol. 2009 Jul;114(1):192-202. doi: 10.1097/AOG.0b013e3181aef106.

 

American College of Obstetricians and Gynecologists. Practice bulletin no. 116: Management of intrapartum fetal heart rate tracings. Obstet Gynecol. 2010 Nov;116(5):1232-40. doi: 10.1097/AOG.0b013e3182004fa9.

Initial Approval:  March 2014.  Revised July 2017. Reaffirmed January 2019

 

********** Notice Regarding Use ************

The Foundation for Exxcellence in Women’s Health, Inc (“Foundation”) is committed to accuracy and will review and validate all Pearls on an ongoing basis to reflect current practice.

This document is designed to aid practitioners in providing appropriate obstetric and gynecologic care. Recommendations are derived from major society guidelines and high quality evidence when available, supplemented by the opinion of the author and editorial board when necessary. It should not be construed as dictating an exclusive course of treatment or procedure to be followed.

Variations in practice may be warranted when, in the reasonable judgment of the treating clinician, such course of action is indicated by the condition of the patient, limitations of available resources, or advances in knowledge or technology. The Foundation reviews the articles regularly; however, its publications may not reflect the most recent evidence. While we make every effort to present accurate and reliable information, this publication is provided “as is” without any warranty of accuracy, reliability, or otherwise, either express or implied. The Foundation does not guarantee, warrant, or endorse the products or services of any firm, organization, or person. Neither the Foundation, the ABOG, SASGOG nor their respective officers, directors, members, employees, or agents will be liable for any loss, damage, or claim with respect to any liabilities, including direct, special, indirect, or consequential damages, incurred in connection with this publication or reliance on the information presented.

Copyright 2019 The Foundation for Exxcellence in Women's Health, Inc. All rights reserved.  No re-print, duplication or posting allowed without prior written consent.

 

Back to Search Results