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The JCAHO Sentinel Event Alert, “Preventing InfantDeath and Injury During Delivery,” issued on July 21,2004, pinpointed a need to “develop clear guidelinesfor fetal monitoring of potential high-risk patientsincluding nursing protocols for the interpretation offetal heart rate tracings” and to “educate nurses,residents, nurse midwives and physicians to usestandard terminology to communicate abnormal fetalheart rate tracings.”1 How to address this need is nowresonating among the professional medical andnursing organizations and individual hospitals andhealth care institutions. In recent professionalpublications, the use of the NICHD terminology toaddress these needs is being recommended and beingincorporated in educational activities. The first stepto address a way to standardize EFM terminology isto educate and to familiarize health care professionalswith the NICHD terminology.

This monograph is an effort to address some of theseeducational needs. The monograph summarizes theNICHD nomenclature as identified in the articles,“Electronic Fetal Heart Rate Monitoring ResearchGuidelines for Interpretation” from The NationalInstitute of Child Health and Human DevelopmentResearch Planning Workshop published in the Journalof Obstetric, Gynecologic and Neonatal Nursing(JOGNN), Volume 26, Issue 6, November-December1997 pages 635-640 and in the American Journal ofObstetrics and Gynecology, December 1997, Volume177, No. 6, pages 1385-1390. This monograph also

Purpose of this Monograph

addresses related EFM interpretation issues asoutlined in the ACOG Practice Bulletin, “IntrapartumFetal Heart Rate Monitoring,” Number 62, May2005, pages, 1161-1169.

NCC encourages the reader to obtain the originaldocuments for further review and study.

Why the NICHD Terminology Was DevelopedA lack of consensus was identified in the definitionsand nomenclature related to fetal heart ratemonitoring and the clinical interpretation of fetalheart rate patterns. Therefore, between May 1995 andNovember 1996, the National Institute of ChildHealth and Human Development sponsored aResearch Planning Workshop to address this issue.

A group of investigators was convened to “propose astandardized and rigorously, unambiguously describedset of definitions that can be quantitated… [and] todevelop recommendations for the investigativeinterpretation of intrapartum FHR tracings so that thepredictive value of monitoring could be assessed moremeaningfully in appropriately designed observationalstudies and clinical trials.”2 It was hoped such studieswould yield more evidence-based clinical managementstrategies to address intrapartum fetal compromise.

Applying NICHDTerminology and Other Factors to Electronic Fetal Monitoring Interpretation

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Operational Principles on Using NICHD TerminologyOperational principles for the basis of defining termsand their interpretive value in assessing fetal heartrate tracings were standardized. The most pertinentare listed below:

• Definitions are to be used for visual interpretation.• Definitions would apply to patterns obtained from

a direct fetal electrode or an external Dopplerdevice.

• The paper speed parameters would be 3 cm perminute for the horizontal axis and 30 beats/min percentimeter for the vertical axis. While it wasrecognized that other paper speeds were currentlybeing used and that FHR patterns might differbased on the paper scale used, the same definitionswould apply.

• The focus would be on intrapartum patterns, butthe definitions would be applicable to antepartum observations as well.

• The EFM patterns are defined as periodic orepisodic. Periodic patterns are those that occur withcontractions and episodic patterns are not relatedwith uterine contractions. Uterine activity would bedetermined through the interpretation oftocodynamometer tracings of good quality.

• The components of fetal heart rate tracings do notoccur in isolation and evaluation of fetal heart ratepatterns should take into account all componentsof fetal heart rate pattern, including baseline rate,variability and presence of accelerations ordecelerations. Fetal heart rate tracings should beassessed over time to identify changes and trends.

• Periodic patterns are identified based on the type ofwaveform defined as abrupt vs. gradual onset ofthe deceleration.

• No differentiation between short and long term variability was made because in practice, they are visually determined as a unit.

• EFM patterns are dependent on gestational age sothis is an essential interpretative factor forevaluating an EFM pattern. Maternal medicalstatus, prior fetal assessment results, use ofmedications and other factors also may need to be considered.3

Terminology and Definitions4

FETAL HEART RATE BASELINEThe mean fetal heart rate is rounded to increments of5 beats per minute during a 10-minute segmentexcluding periodic/episodic changes, periods ofmarked variability or baseline segment that differ bymore than 25 beats per minute.

In any given 10 minute window, the minimumbaseline duration must be at least 2 minutes.Otherwise, it is considered indeterminate. In theseinstances, review of the previous 10 minute segmentshould be the basis on which to determine thebaseline.

In determining the baseline rate, a minimum of a 10-minute period of monitoring is necessary forconfirmation of the rate.

The fetal baseline rate is classified as follows:

Normal: 110 to 160 beats per minute

Bradycardia: Less than 110 beats per minute

Tachycardia: Over 160 beats per minute

FETAL HEART RATE PATTERNSDetermination of baseline fetal heart rate variability isbased on visual assessment and excludes sinusoidalpatterns.

Variability is defined as fluctuations in the fetal heartrate baseline that are two cycles per minute or moreand that are irregular in amplitude.

The visual quantification of the amplitude from peakto trough in beats per minute is as follows:

Amplitude Range Classification

Undetectable Absent

Undetectable to equal to orless than 5 beats per minute Minimal

6 to 25 beats per minute Moderate

More than 25 beats per minute Marked

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Sinusoidal patterns which are excluded from thedefinition of variability are described as a smooth,sine wave-like pattern of regular frequency andamplitude.

ACCELERATIONSBased on visual assessment, an acceleration is definedas an apparent abrupt increase in fetal heart rateabove the baseline. Onset to peak is equal to or lessthan 30 seconds and duration is equal to or morethan 15 seconds and less than two minutes from onsetto return to baseline.

In pregnancies less than 32 weeks gestation,accelerations are defined as an increase of 10 beatsper minute or more above baseline which lasts 10seconds or more.

An acceleration is classified as prolonged if theduration is 2 minutes or more but less than 10minutes. Accelerations that are 10 minutes or moreare considered a baseline change.

LATE DECELERATIONSBased on visual assessment, a late deceleration isdefined as an apparent gradual decrease in fetal heartrate and return to baseline associated with uterinecontractions. Onset to nadir is equal to or greaterthan 30 seconds. The nadir of the deceleration occursafter the peak of the contraction.

EARLY DECELERATIONSBased on visual assessment, an early deceleration isdefined as an apparent gradual decrease in fetal heartrate and return to baseline associated with uterinecontractions. Onset to nadir is equal to or greaterthan 30 seconds. The nadir of the deceleration occursat the same time of the peak of the contraction.

VARIABLE DECELERATIONSBased on visual assessment, a variable deceleration isdefined as an apparent abrupt decrease in fetal heartrate below the baseline which may or may not beassociated with uterine contractions. Onset to nadiris less than 30 seconds. The decrease in fetal heartrate below the baseline is equal to or more than 15beats per minute, lasting 15 seconds or more but lessthan 2 minutes in duration from onset to return tobaseline. When variable decelerations occur inconjunction with uterine contractions, the onset,depth and duration vary with each succeeding uterinecontraction.

PROLONGED DECELERATIONBased on visual assessment, a prolonged decelerationis defined as an apparent decrease in fetal heart ratebelow the baseline. The decrease in the fetal heartrate is 15 beats per minute or more and lasts for atleast 2 minutes but less than 10 minutes from onset toreturn to baseline. A prolonged deceleration that issustained for 10 minutes or more is a baseline change.

Quantification of the VisualInterpretation of the Fetal Heart Rate BaselineThe quantification of a deceleration is made by thedepth of nadir in beats per minute below the baselineand excludes transient spikes or electronic artifact. Theduration of decelerations is quantified in minutes andseconds from the beginning to end of the deceleration.The same principles apply to accelerations as well.

Decelerations are identified as recurrent if they occurwith 50% or more of uterine contractions in any 20minute segment.

The quantification of bradycardia and tachycardia arebased on the actual fetal heart rate in beats perminute.

If the fetal heart rate is not stable, it can bedetermined by the visual range of the fetal heart rate.

Uterine Activity5

While the NICHD terminology did not addressdefining uterine activity, the following lists some basicprinciples that are well accepted in assessing uterineactivity.

• Uterine activity can be assessed by palpation orexternal or internal fetal monitoring.

• In normal labor, contractions occur about every 2-5minutes, with a duration of 30-60 seconds. Uterinecontraction strength increases as labor progresses.

• Frequency of contractions is defined from thebeginning of one contraction to the onset of nextcontraction described in minutes.

• Duration or length of a uterine contraction isdescribed in seconds and is counted from beginningto the end of contraction.

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• Intensity or strength of contractions can bedetermined by palpation or quantification ofintraamniotic pressure by an internal intrauterinepressure catheter (IUPC).

• Uterine intensity is described as mild, moderate orstrong when assessed by palpation and in mm Hgwhen assessed by an IUPC.

• Resting tone is the time between contractions andcan be assessed by palpation or intraamnioticpressure by an IUPC.

• Resting tone is described as soft or rigid bypalpation in mm Hg when assessed by IUPC.

Clinical Considerations6

The primary purpose for the use of electronic fetalmonitoring is to determine if the fetus is welloxygenated. The guidelines for review of electronicmonitor tracing during the intrapartum period arebased on the stage of labor and the status of thepregnancy and these guidelines are identified below:

First Stage Second Stageof Labor of Labor

Pregnancy Without Complications 30 minutes 15 minutes

Pregnancy With Complications 15 minutes 5 minutes

CHARACTERISTICS OF REASSURING ANDNONREASSURING FETAL HEART RATETRACINGSA reassuring pattern is the presence of fetal heart rateaccelerations. This usually indicates there is no acidemiaand is generally indicative of fetal well being. In mostcases, moderate variability is also reassuring but fewstudies exist to support this contention.

When the fetal heart has absent or minimal variabilitywithout spontaneous accelerations and the fetal heartrate status does not change despite intervention, thesefindings are nonreassuring.7 Nonreassuring is thestandard terminology to be used to describe threats tofetal well being or indicators of fetal compromise. Thisterm replaces such terms as fetal distress or fetal stress.8

FACTORS AFFECTING FETAL HEART RATE PATTERNSThere are many likely factors that can have an effecton the fetal heart rate. Fetal heart rate changes canoccur in response to pre-existing or pregnancy-relatedconditions, medications given to the woman in laborand environmental influences. Below are charts thatidentify possible factors and the associated fetal heartrate change(s). These fetal heart rate changes may betransient and benign or require further monitoringand/or intervention. While more study may be neededto confirm some of these associations, they areincluded based on the prevailing consensus ofinformation known at this time.

The Influence of Medications on Fetal Heart Rate

Medication Change in Fetal Heart RateBetamethasone Decrease in FHR variabilityButorphanol Pseudosinusoidal benign patternCocaine No changeMagnesium sulfate Decrease in FHR baseline

& variabilityMeperidine No changeMorphine Decrease in the number of

accelerations that occurTerbutaline Decrease in frequency of

variable declerations Zidovidine No changeDerived from “Intrapartum Fetal Heart Rate Monitoring,” ACOG PracticeBulletin, No. 62, May 2005, p. 1165

The Influence of Environmental or Fetal Factors on the Fetal Heart Rate

Environmental Factor Change in Fetal Heart Rate

Scalp or vibroacoustic stimulation AccelerationsSpontaneous fetal movement AccelerationsUterine contractions Accelerations or

early decelerationsVaginal or pelvic examination AccelerationsDerived from Fetal Monitoring and Assessment, Tucker, Mosby, St. Louis,2004 pages. 110-115, 126-142, and 153-154.

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The Influence of Maternal or Fetal Conditions on the Fetal Heart Rate

Maternal or Fetal Factors Change in Fetal Heart RateCongenital heart block BradycardiaMaternal fever or fetal infection TachycardiaMaternal hyperthyroidism TachycardiaMaternal hypotension Prolonged decelerations/

bradycardia and latedeclerations

Maternal supine hypotension Late decelerations,bradycardia

Oligohydramnios Variable decelerationsPlacenta previa/abruption Late decelerationsProfound fetal hypoxia BradycardiaProlonged cord compression Prolonged decelerations/

bradycardiaRegional anesthetics Late decelerationsTetanic contractions Prolonged decelerationsUmbilical cord compression Variable decelerationsUterine hyperstimulation Late decelerationsDerived from Fetal Monitoring and Assessment, Tucker, Mosby, St. Louis,2004 pages. 110-115,126-142, and 153-154.

GENERAL CONSIDERATIONS9

In consideration of the clinical applicability ofelectronic fetal monitoring and its efficacy, consistentscientific evidence supports the following:

• Electronic fetal monitoring has a high false positiverate for predicting adverse outcomes.

• With the use of electronic fetal monitoring, there isan increased rate of operative interventions:cesarean delivery, forceps delivery and use ofvacuum extraction.

• Electronic fetal monitoring is not useful in reducingthe incidence of cerebral palsy.

• Amnioinfusion is useful in avoiding emergentcesarean delivery in the presence of recurrent variabledecelerations.

ConclusionElectronic fetal monitoring can be useful in assessingthe fetal status during labor. It has limitations andbenefits but it will be most beneficial when all healthcare personnel providing care to women in labor useconsistent language in describing the fetal heart ratepatterns and other information elicited from the fetalmonitor. No one terminology is inherently betterthan another. The value of a common language is thateveryone has the same understanding and hencepatient safety is increased by decreasing the risk ofmiscommunication. Agreement on a commonlanguage and its use is one the best safeguards inpreventing errors and avoiding miscommunication.This monograph focuses on the NICHD language as away of sharing information.

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APPENDIXRepresentative tracings demonstrating NICHD

terminology are listed below:

VARIABILITY

Absent Variability

Minimal Variability

Moderate variability

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Marked Variability

Sinusoidal pattern

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BASELINE RATE

1916-22

Normal

Tachycardia

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Bradycardia

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PERIODIC PATTERNS

Early Decelerations

Variable Decelerations

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Prolonged Deceleration

Late Decelerations

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REFERENCES

1 Sentinel Event Alert, Issue #30, Preventing Infant Death and Injury During Delivery, www.jcaho.org/about+us/news+letters\sentinel+event+alert/sea>30htm.

2 “Electronic Fetal Heart Rate Monitoring Research Guidelines for Interpretation” from The National Instituteof Child Health and Human Development Research Planning Workshop, Journal of Obstetric, Gynecologic and Neonatal Nursing (JOGNN), Volume 26, Issue 6, November-December 1997, p. 636

3 “Electronic Fetal Heart Rate Monitoring Research Guidelines for Interpretation” from The National Instituteof Child Health and Human Development Research Planning Workshop, American Journal of Obstetrics andGynecology, December 1997, Volume 177, No. 6, p.1386.

4 “Electronic Fetal Heart Rate Monitoring Research Guidelines for Interpretation” from The National Instituteof Child Health and Human Development Research Planning Workshop, American Journal of Obstetrics andGynecology, December 1997, Volume 177, No. 6, p.1386-1388.

5 Fetal Monitoring and Assessment, Tucker, Susan, Mosby, St. Louis, 2004, pages pgs. 85-91.

6 ACOG Practice Bulletin, Intrapartum Fetal Heart Rate Monitoring, Number 62, May 2005, American College of Obstetricians and Gynecologists, Washington, DC, page 1163.

7 Fetal Monitoring and Assessment, Tucker, Susan, Mosby, St. Louis, 2004, pages page 159

8 Fetal Monitoring and Assessment, Tucker, Susan, Mosby, St. Louis, 2004, pages page 159

9 ACOG Practice Bulletin, “Intrapartum Fetal Heart Rate Monitoring,” Number 62, May 2005, American College of Obstetricians and Gynecologists, Washington, DC, page 1167.

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REVIEWERS

NCC thanks the following individuals for their contributions to thedevelopment of this monograph.

Mary Brucker, CNM, DNSc,Director of Graduate StudiesThe Louise Herrington School of NursingBaylor UniversityDallas, TX

Mary Ellen Burke Sosa, RNC, MSAssistant Diabetes ClinicianPer Diem Shift NurseWomen & Infants’ HospitalProvidence, RI

Joyce Converse, RNC, MSVice President, Soyring ConsultingColorado Springs, CO

David S. McKenna, MD, FACOGClinical Associate Professor of Obstetrics & GynecologyWright State University School of MedicineDayton, OH

Sharon Oroco, RNC, MS, CLCProject Manager Women’s ServicesMiami Valley HospitalDayton, OH

Kathleen Rice Simpson, RNC, Ph. D, FAANPerinatal Clinical Nurse SpecialistSt. John’s Mercy Medical CenterSt. Louis, MO

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