efm r penting

Review

Intrapartum Electronic Fetal Heart RateMonitoring and the Prevention of PerinatalBrain InjuryErnest M. Graham, MD, Scott M. Petersen, MD, Dana K. Christo, MPH, and Harold E. Fox, MD, MSc

OBJECTIVE: Electronic fetal heart rate monitoring (EFM)is the most widely used method of intrapartum surveil-lance, and our objective is to review its ability to preventperinatal brain injury and death.

DATA SOURCES: Studies that quantified intrapartumEFM and its relation to specific neurologic outcomes(seizures, periventricular leukomalacia, cerebral palsy,death) were eligible for inclusion. MEDLINE was searchedfrom 1966 to 2006 for studies that examined the relation-ship between intrapartum EFM and perinatal brain injuryusing these MeSH and text words: cardiotocography,electronic fetal monitoring, intrapartum fetal heartrate monitoring, intrapartum fetal monitoring, andfetal heart rate monitoring.

METHODS OF STUDY SELECTION: This search strategyidentified 1,628 articles, and 41 were selected for furtherreview. Articles were excluded for the following reasons: incase reports, letters, commentaries, and review articles,intrapartum EFM was not quantified, or specific perinatalneurologic morbidity was not measured. Three observa-tional studies and a 2001 meta-analysis of 13 randomizedcontrolled trials were selected for determination of theeffect of intrapartum EFM on perinatal brain injury.

TABULATION, INTEGRATION, AND RESULTS: Electronicfetal monitoring was introduced into widespread clinicalpractice in the late 1960s based on retrospective studiescomparing its use to historical controls where ausculta-tion was performed in a nonstandardized manner. Case-control studies have shown correlation of EFM abnormal-ities with umbilical artery base excess, but EFM was notable to identify cerebral white matter injury or cerebral

palsy. Of 13 randomized controlled trials, one showed asignificant decrease in perinatal mortality with EFM com-pared with auscultation. Meta-analysis of the randomizedcontrolled trials comparing EFM with auscultation havefound an increased incidence of cesarean delivery anddecreased neonatal seizures but no effect on the inci-dence of cerebral palsy or perinatal death.

CONCLUSION: Although intrapartum EFM abnormalitiescorrelate with umbilical cord base excess and its use isassociated with decreased neonatal seizures, it has no effecton perinatal mortality or pediatric neurologic morbidity.(Obstet Gynecol 2006;108:65666)

In 2002, approximately 85% of the 4 million livebirths in the United States were assessed withelectronic fetal monitoring (EFM), making it the mostcommon obstetric procedure.1 Electronic fetal moni-toring during labor plays a central role in the currentlitigation crisis in obstetrics. This issue recently gainedwidespread attention in the lay press when in 2004one of the candidates for president of the UnitedStates, a successful plaintiffs attorney, published abook justifying his entry into politics that expoundedupon four successful trials that had occurred over thecourse of his career before his retirement from thepractice of law at the age of 45 with an estimatedpersonal worth of up to $70 million dollars.2,3 Of thefour trials discussed in this book, two are medicalmalpractice cases, of which one is a case of an infantwith cerebral palsy where it is alleged that deliveryshould have occurred sooner because of abnormali-ties in the electronic fetal heart rate (FHR) tracing.Case 2 in the book, the delivery of Jennifer C.,occurred in 1979 and was a total breech extraction ofa term infant from a footling breech presentation.2

This infant had Apgar scores of 1 and 2 at one andfive minutes, a fractured clavicle, required emergencyneonatal resuscitation, developed seizures, and wasdiagnosed with cerebral palsy 3 months after leaving

From the Department of Gynecology and Obstetrics, Division of Maternal-FetalMedicine, Johns Hopkins University School of Medicine, Baltimore, Maryland;and Department of Epidemiology, Bloomberg School of Public Health, JohnsHopkins University, Baltimore, Maryland.

Corresponding author: Ernest M. Graham, MD, Johns Hopkins Hospital,Department of Gyn-Ob, Phipps 220, 600 N. Wolfe Street, Baltimore, MD21287-1228; e-mail: [email protected].

2006 by The American College of Obstetricians and Gynecologists. Publishedby Lippincott Williams & Wilkins.ISSN: 0029-7844/06

656 VOL. 108, NO. 3, PART 1, SEPTEMBER 2006 OBSTETRICS & GYNECOLOGY

the hospital. Although not mentioned in the initialtelling of the delivery story, later during the trial it isstated that metal forceps had been applied to theemerging head.2 For attempting a vaginal deliveryof a term footling breech infant rather than perform-ing a cesarean, the delivering obstetrician settled for$1.5 million in 1985. If the case had ended here, itwould have been an unremarkable medical malprac-tice case, but in an attempt to sue the hospital theplaintiff changed this case from one of birth trauma toone of hypoxia-ischemia manifested for hours beforedelivery in the electronic FHR tracing. In his bookthis plaintiffs attorney states that First, I had tobecome an overnight expert in fetal monitor read-ings.2 He states that there were variable decelera-tions on the monitor strip that indicated cord com-pression.2 In closing arguments at trial he states that. . .(the fetus) did everything she knew how todo. . .to speak to the hospital, and the only way sheknew how to do it was through that strip. . .. Atfive-thirty she said I need out. At six the cries gotweaker. . .and the cries heard were the cries of Jen-nifer C. dying. . . .But now she speaks to you, notthrough a fetal monitor strip; she speaks to you (thejury) through me.2 The jury returned a $6.5 millionverdict against the hospital. Because of the extensiveclinical use of EFM and its involvement in litigation,the objective of this review is to estimate how effectiveintrapartum EFM is in preventing perinatal braininjury or death.

SOURCESWe sought to identify studies that assessed the rela-tionship between intrapartum EFM and perinatalneurologic morbidity. Eligibility for inclusion wasdetermined by the following criteria: studies had toreport quantification of FHR using intrapartum EFMand assess outcomes related to brain injury (ie, sei-zures, periventricular leukomalacia, cerebral palsy,death). We searched MEDLINE for English languagearticles from January 1966 to April 2006 using thefollowing search terms as Medical Subject Headings(MeSH) and text words as appropriate: cardiotocog-raphy (as MeSH term and text word), electronicfetal monitoring (text words), intrapartum fetalheart rate monitoring (text words), intrapartum fetalmonitoring (text words), and fetal heart rate moni-toring (text words).

STUDY SELECTIONThis search strategy identified 1,628 articles. Articleswere excluded for the following reasons: in casereports, letters, commentaries, and review articles,

electronic fetal monitoring was not evaluated as theintervention, perinatal brain injury was not the mainoutcome, or some combination of the aforementionedfactors. Abstracts were reviewed by two investigators,and 41 articles met the criteria for further review. Twoinvestigators independently reviewed full-text articlesand determined study eligibility. Of the 41 studies, 13were excluded because they were randomized clinicaltrials that were included in later meta-analyses4,5 anda more recent Cochrane Review that was selected foranalysis.6 Of the remaining 28 studies, 12 were ex-cluded because of lack of identification of a specificneurologic outcome, 10 because of the lack of aquantitative EFM parameter, one because it wasunclear how patients were divided into high and lowrisk groups, one because it was a synthesis of random-ized and nonrandomized trials, and one because birthasphyxia was defined by a 5-minute Apgar score lessthan 7 rather than by using a cord gas assessment.Three observational studies met the inclusion criteriafor this review (Table 1).79 Reference lists fromrelevant original research and review articles weremanually searched for additional studies. A descrip-tion of the studies that met eligibility criteria ispresented in this article within the historical context ofEFM. Data from these observational studies were notcombined because of differences inmeasured outcomes.

RESULTSThe common practice of monitoring the FHR duringlabor was stimulated by William Little, a Londonorthopedic surgeon caring for spastic infants, who in1862 expressed the view that the process of birth wasresponsible for the pathology of cerebral palsy.10 TheFHR of the laboring woman was traditionally auscul-tated during labor with either a stethoscope or feto-scope, but during the late 1950s research into externaland internal methods to monitor the FHR duringlabor began to be developed. Edward Hon of YaleUniversity and subsequently of the University ofSouthern California was a physician and engineerwho conceived the internal monitor and inventedthe electrode, which made it possible to connect thefetus to the machine to collect the electrocardio-graphic information.11 Roberto Caldeyro-Barcia inMontevideo, using a paper speed of 1 cm/min, iden-tified 2 types of FHR decelerations: type 1 dips weresimultaneous with uterine contractions, and type 2dips (late decelerations) persisted after the contractionhad ended. Type 1 decelerations were not associatedwith fetal depression at birth, but type 2 decelerationswere.12 Using a faster recording speed of 3 cm/min,Hon was able to differentiate 3 patterns of FHR

VOL. 108, NO. 3, PART 1, SEPTEMBER 2006 Graham et al Electronic Fetal Monitoring 657

decelerations: early, variable, and late. These earlyinvestigators agreed that fetal depression was morelikely to be associated with late and severe variabledecelerations, which they confirmed by measuringthe pH of fetal scalp blood at the time of thesedecelerations. Late and severe variable decelerationswere associated with significant reductions in meanpH, whereas early decelerations and mild-to-moder-ate variable decelerations were not.13 Fetal heart ratevariability was found to be an important indicator offetal well-being, which could differentiate betweenfetuses with similar deceleration patterns who weremore likely to be acidemic or depressed at birth.14

This research led to more specific guidelines as tohow intermittent auscultation should be performedduring labor. Whereas it had previously been done ina nonstandardized manner, the identification of thesedeceleration types led to the practice of auscultatingthe fetal heart rate immediately after a contraction.Electronic fetal monitoring was introduced into wide-spread clinical practice in the late 1960s based on

retrospective studies which compared its use withhistorical controls where auscultation was performedin a nonstandardized manner.

In term monkey fetuses severe asphyxia wasnoted to lead to episodes of fetal bradycardia andhypotension associated with late decelerations.15

After prolonged survival, the cerebral damage pro-duced by partial asphyxia in term monkey fetusesproduced brain lesions that resembled closely thelesions of human perinatal injury or cerebral palsy.Because of the close similarities between the brainpathology associated with partial asphyxia in uteroin the term monkey fetus and the pathology ofcerebral palsy in the human, this investigator con-cluded that partial asphyxia in utero may play amajor role in the pathogenesis of cerebral palsy inthe human. He also felt that, when late decelera-tions are first recognized and their existence con-firmed, immediate delivery of the embarrassedfetus should be considered. In 1969, it was claimedthat 90% of all fetal distress is caused by umbilical

Table 1. Studies Quantitating the Relationship Between Intrapartum Electronic Fetal Monitoring andNeurologic Morbidity

Study Date Design N Neurologic Outcomes

Yeh et al7 1982 Retrospective withhistorical controls

115,096 Deliveries over 10years from 1970 to 1979

1970: EFM18%, PNM18/1,000

1979: EFM74%, PNM11/1,000Intrapartum death: EFM1.5/1,000,Aus2.5/1,000, P.005

Neonatal death: EFM8.1/1,000,Aus14.7/1,000, P.001

Nelson et al8 1996 Case-control EFM abnormalitiescompared between 78fetuses with cerebral palsyand 300 controls

Multiple late decels: OR 3.9, 95% CI 1.79.3

Decreased variability: OR 2.7, 95% CI1.15.8

21/78 (27%) with cerebral palsy had EFMabnormality

0.2% of children with these EFMabnormalities had cerebral palsy (falsepositive rate of 99.8%)

Althaus et al9 2005 Case-control 136 Vaginal deliveries(47.1% with PVL)

During last hour of EFM prior to deliverythere was no difference in total decels,late decels, or decreased variability.

110 Cesarean deliveries(55.5% with PVL)

Significant correlation found betweenumbilical artery base excess and numberof late decels (r0.18, P.01)

Thacker et al6 2001 Meta-analysis of 9/13RCTs

N18,927 (50% EFM) forneonatal seizures andperinatal death

Neonatal seizures: RR 0.51, 95% CI 0.320.82

Perinatal death: RR 0.89, 95% CI 0.601.33

N13,325 (50% EFM) forcerebral palsy

Cerebral palsy: RR 1.66, 95% CI 0.923.00

EFM, electronic fetal monitoring; PNM, perinatal mortality; Aus, auscultation; decels, decelerations; OR, odds ratio; CI, confidence interval; RR,relative risk; PVL, periventricular leukomalacia; RCTs, randomized controlled trials.

658 Graham et al Electronic Fetal Monitoring OBSTETRICS & GYNECOLOGY

cord compression and that electronically monitor-ing the entire birth process from labor to deliverycould save as many as 20,000 babies a year andreduce the number of injured babies by 50%.16

In 1971, President Nixons Commission on Men-tal Retardation adopted as a national goal To reduceby half the occurrence of mental retardation in theUnited States before the end of this century.17 Mostinvestigators felt that, because the stress of labor isclearly capable of causing fetal death, it did not seemunreasonable to assume that labor may also be afactor in producing brain damage, which is merely anintermediate point on the pathway to death. A studyof 24,863 laboring patients, monitored with intermit-tent auscultation according to a schedule well beyondthe nursing observation capabilities of most obstetricunits, found there was no single reliable indicator ofthe fetus in trouble in terms of the FHR except withan extreme degree of terminal bradycardia, whichshowed the inadequacies of auscultation as a form ofintrapartum surveillance.18 Based on the assumptionsthat half of institutionalized individuals with severemental retardation had causative factors directlylinked to delivery and that continuous FHR monitor-ing during labor would reduce perinatal mortality andmorbidity by 50%, a cost analysis published in 1975concluded that EFM presented attractive potentialsfor enhancing the quality of maternal-fetal health careand the future of its recipients, although it was ac-knowledged that to date, there has been no definitivewell-controlled study which has scientifically proventhe value of this technique.19

A number of studies published in the 1970spointed to the drop in perinatal morbidity and mor-tality that had occurred since the introduction of EFMand attributed this to EFM. During a 10-year periodfrom 1970 to 1979, the obstetric service at the Uni-versity of Southern California found that after EFMwas introduced in 1969 the perinatal mortality ratedecreased as the EFM rate increased, from 18% in1970 to 74% in 1979 (Table 1).7 The major compo-nents of the decrease in the mortality rate were in theintrapartum and neonatal deaths. The antepartumdeath rate remained relatively consistent throughoutthe 10-year period, which the authors attributed to thelack of EFM in the antepartum period. The cesareandelivery rate increased during this period from 9.3%in 1970 to 12.3% in 1979, but the authors did notascribe this increase to EFM but rather to the fact thathigh-risk patients, who were coincidentally at higherrisk for cesarean delivery, were more likely to haveEFM, as well as to an increased rate of cesareandelivery for breech and premature infants during this

period. A proposed large randomized controlled trialof the effect of EFM on neonatal outcome proposedfor the University of Southern CaliforniaLos Ange-les County Womens Hospital was rejected because itwas considered unethical to withhold EFM frompatients in the control arm of the study.20 In 1975,investigators from this institution noted that, althougha controlled study of a statistically adequate numberof patients had not been done, given the apparentclinical usefulness of this new technology it might beethically difficult to obtain such data.21 Studies done atthe University of Southern California at this time donot mention funding from the company Corometrics,which produced the electronic fetal monitor or pat-ents held by investigators in the studies.22 The rulesinvolving conflict of interest were not well definedduring this period.

The first randomized controlled trial of EFM didnot reach the same conclusions as the earlier studiesdone using historical controls. In 1976, a prospectiverandomized study in Denver of 483 high-risk patientsin labor, monitored either electronically or with inter-mittent auscultation, found that the cesarean rate wasmarkedly increased in the EFM group (16.5% versus6.8%), but there was no difference in neonatal death,Apgar scores, cord blood gases, or neonatal morbid-ity.23 The primary author had begun this randomizedcontrolled trial because many women rejected EFMand he wished to demonstrate its usefulness to con-vince both women and skeptical obstetricians of itsvalue. He was surprised to find no advantages forEFM over auscultation.24 This result was unexpectedand generated controversy immediately. Althoughthere was no significant difference in the number ofpatients with ominous FHR patterns (defined as lateor severe variable decelerations) between the EFMand auscultation groups overall, in early labor at lessthan 5 cm dilatation, the EFM group had significantlymore of these ominous findings. It was alleged thatentry into the study was not masked and that morehigh-risk patients were assigned to the EFM group.This distinction was thought to explain the failure ofEFM to decrease perinatal morbidity or mortality.25

Two epidemiologists from the Department ofHealth, Education, and Welfares Office of Technol-ogy Assessment issued a review of EFM in 1978preceded by a short report entitled Electronic FetalMonitoring May Do More Harm Than Good.26

They found that EFM was associated with a higherrisk of infection and cesarean delivery, but no demon-strable fetal benefit, and concluded that widespreadEFM use produced uncertain benefits and substantialrisks at a very high cost. The report was immediately


criticized as a government attempt to decrease healthcare costs by eliminating an exciting new technology,and the authors were criticized personally for neverhaving done a residency in obstetrics (although bothwere trained in epidemiology and biostatistics, one ofthe authors had completed a residency in familypractice which included clinical obstetrics).24 Promi-nent obstetrician advocates of EFM defended it inrebuttals published in the journals Obstetrics & Gyne-cology and Pediatrics.27,28 These authors did not ac-knowledge the additional weight given randomizedcontrolled trials over retrospective studies and did notaccept that statisticians could review all availableliterature, most of which favored EFM, and not cometo a conclusion favoring the routine use of EFM.24

A 1979 study combined data from 10 nonran-domized studies and concluded that there is nowcompelling evidence that the intrapartum stillbirthrate will decrease by 12 in 1,000, and neonataldeaths will be halved if monitoring is widely used.. . .Reverence for the negative findings in the fourrandomized trials may be misplaced because of thegrossly inadequate numbers and the unrepresentativenature of the patients.29 This investigator believedthat most benefit would be seen in high-risk patients,especially premature babies, but that several studiessuggest that low-risk patients can also benefit, proba-bly to the extent of one life saved per 1,000.29 In thestudies comparing EFM to historical controls, all thebenefits in perinatal morbidity and mortality areascribed to EFM, and no consideration is given toother factors that were changing during this period,such as the increasing use of ultrasonography, ante-natal testing, legal abortion, increased obstetric sur-veillance, the development of the specialty of mater-nal-fetal medicine, and improvements in neonatalintensive care, which would decrease both fetal andneonatal mortality.

The first two decades after the introduction ofEFM in the United States in the late 1960s were aperiod of rapid increase in litigation claiming negli-gent injury to the fetus during labor. In medicalmalpractice trials at the time, a local standard rulewas used, which meant that scientific evidence wasadmissible but was considered weaker than the actualpractice of respected clinicians.24 Because the routineuse of EFM had become standard practice in manyareas, the decision not to monitor electronically wasoften used in these suits as a reason to claim thatmalpractice had resulted in the damage.30 In 1981, afederal jury in Oklahoma City found an obstetricianguilty of medical malpractice for not using EFM in thecase of a 3-year-old child with brain damage and

ordered the payment of $2 million, the largest med-ical malpractice verdict in the state of Oklahoma atthat time.31 Testimony indicated that meconium-stained fluid was noted during labor, but the obstetri-cian continued to monitor labor by intermittent aus-cultation. The plaintiffs attorney argued that thepresence of meconium-stained fluid indicated that thepregnancy was high risk and that EFM should havebeen instituted. Without EFM the childs oxygenstarvation was not adequately diagnosed nor properemergency treatment taken to minimize the risk ofbrain damage. A front-page article reporting on thetrial noted that Fetal monitors have been the subjectof controversy because some experts feel they have adegree of error that can cause medical personnel tooverreact, leading to what might be an unnecessarycesarean birth,31 and also that The trial aired testi-mony by some of the most noted medical authoritiesin the country including Dr. Edward Hon, the obste-trician who invented the monitor which has becomestandard equipment in many hospitals.31 The plain-tiffs attorney stated that the trial was significantbecause it was considered by experts to be thebattleground for the fetal heart monitor, and thatthe trial may convince hospitals to use the monitormore often.31

It was originally hoped that this new technologywould help change obstetrics from an art to ascience in identifying the compromised fetus.32 Crit-icisms of the early trials of EFM led to several verylarge clinical trials. The largest of these, performed inDublin between 1981 and 1983, randomized 12,964women to either EFM or auscultation.33 The cesareandelivery rate was 2.4% in the EFM group and 2.2% inthe auscultation group. There were 14 stillbirths andneonatal deaths in each group, with a similar distri-bution of causes. There were no apparent differencesin the rates of low Apgar scores, need for resuscita-tion, or transfer to the special care nursery. Cases ofneonatal seizures and persistent abnormal neurologi-cal signs followed by survival were twice as frequentin the intermittent auscultation group, but when thenine children from the EFM group and the 21 chil-dren from the intermittent auscultation group whosurvived after neonatal seizures were followed up at 4years of age, there were 3 children with cerebral palsyin each group.34 They also found that eight childrenfrom the EFM group and seven from the controlgroup who had not had abnormal neurological signsin the neonatal period developed cerebral palsy, andthat 16 of 22 (78%) infants who developed cerebralpalsy had no clinical evidence of intrapartum as-


phyxia. Compared with intermittent auscultation,EFM had no protective effect against cerebral palsy.

The incidence of cerebral palsy is much higher inpreterm infants. At term, the incidence of cerebralpalsy is 12 in 1,000 births, but at 24 weeks ofgestation, 25% of survivors develop cerebral palsy.35

By studying a high-risk group of preterm infants, itwas hoped that EFM would demonstrate benefit. Amulticenter randomized clinical trial compared theneurologic development of 93 premature infantsmonitored electronically with 96 monitored by aus-cultation. All infants in this study were singletons,cephalic, and weighed less than 1,750 g at birth.36

Mental and psychomotor development were mea-sured at three follow-up visits scheduled at 4, 8, and18 months of age, corrected for the degree of prema-turity. The incidence of cerebral palsy was higher inthe group monitored electronically (20% EFM, 8%auscultation, P.03). The median time to deliveryafter the diagnosis of abnormal FHR patterns was 104minutes with EFM compared with 60 minutes withperiodic auscultation. In infants weighing less than1,750 g who had EFM, there was an unanticipated2.9-fold increase in the odds of having cerebral palsycompared with those who had periodic auscultation.This increase was observed at each of the three studyhospitals. They concluded that, compared with astructured protocol of periodic fetal auscultation,EFM does not improve the neurologic developmentof premature infants.

A 1995 meta-analysis, performed by searchingthe MEDLINE database for the period 19661994,contacting experts, and reviewing published refer-ences, identified 12 published randomized controlledtrials that examined the efficacy of EFM.5 These 12studies included 58,855 pregnant women and their59,324 infants in both high- and low-risk pregnanciesfrom 10 clinical centers in the United States, Europe,Australia, and Africa. Electronic fetal monitoring wasfound to decrease the risk of neonatal seizures com-pared with auscultation. The protective effect forneonatal seizures was evident only in studies withhigh quality scores. No significant differences werefound between the EFM and auscultation groups in1-minute Apgar scores less than 7, admission to theneonatal intensive care unit, or perinatal death. Elec-tronic fetal monitoring was associated with an in-creased rate of cesarean delivery and operative vagi-nal delivery. With the exception of the reduction inthe rate of neonatal seizures, the use of EFM had nomeasurable impact on morbidity and mortality, andalthough the benefit in reduction of seizures wasdemonstrated consistently, the long-term impact of

this effect was unclear because the only two studieswith long-term follow-up showed that the effects ofthese seizures were minimal.34,36 Because of the in-creased morbidity associated with cesarean deliveryand the lack of increased neurologic morbidity laterfound in children who had seizures after birth, thevalue of EFM in this meta-analysis was uncertain.These authors pointed out that EFM was introducedinto widespread clinical practice before evidencefrom randomized controlled trials demonstrated ei-ther efficacy or safety and that widespread diffusion ofthis technology before efficacy was determined mayhave led to misuse, misunderstanding, and misinfor-mation regarding malpractice litigation.5

Another meta-analysis, also published in 1995, ofthe randomized controlled trials comparing EFM toauscultation also found that EFM was associated withsignificantly higher overall rates of cesarean deliveryand use of forceps and vacuum but found that,although the use of EFM did not reduce overallperinatal mortality, perinatal mortality caused by fetalhypoxia was reduced (odds ratio [OR] 0.41, 95%confidence interval [CI] 0.170.98).4 Specific criteriaas to how they defined fetal hypoxia were not given,and because no information regarding cord gases isgiven in these studies, there is no objective way todefine intrapartum hypoxia-ischemia. An AmericanCollege of Obstetricians and Gynecologists (ACOG)educational bulletin that reviewed intrapartum EFMpointed out that the results of this meta-analysis werebased on a small number of events and were statisticallyunstable.37 If there had been one fewer case of perinataldeath in the auscultation group, the results of the meta-analysis would not have been statistically significant.37

In a 2001 meta-analysis by the Cochrane collab-oration of 13 published randomized controls trialsaddressing the efficacy and safety of EFM, four trialswere excluded for not fulfilling selection criteria, andonly one showed a significant decrease in perinatalmortality with EFM compared with intermittent aus-cultation (Table 1).6 This meta-analysis concludedthat the routine use of continuous EFM reduced theincidence of neonatal seizures (relative risk [RR] 0.51,95% CI 0.320.82) but had no effect on the incidenceof cerebral palsy (RR 1.66, 95% CI 0.923.00) orperinatal death (RR 0.89, 95% CI 0.601.33). Theseinvestigators felt that, in view of the increase incesarean (RR 1.41, 95% CI 1.231.61) and operativevaginal delivery (RR 1.20, 95% CI 1.111.30) and thelack of long-term pediatric benefit, EFM did not offera clear advantage over ausculation.6 With one excep-tion,38 in none of these randomized controlled trialswere there prospectively defined protocols for the


interpretation or management of abnormal FHR pat-terns. These randomized clinical trials may all havemeasured efficacy (value under optimal clinical con-ditions) rather than effectiveness (value in routineclinical practice), which means that the actual benefitof EFM may be even less in day-to-day obstetricpractice.5

A study of 78 term singleton children born in fourCalifornia counties between 1983 and 1985, whoweighed at least 2,500 g at birth and survived to 3years of age with the diagnosis of moderate-severecerebral palsy, compared the electronic FHR tracingsof these children with 300 randomly selected termcontrols (Table 1).8 Multiple late decelerations (OR3.9, 95% CI 1.79.3) and decreased beat-to-beat vari-ability (OR 2.7, 95% CI 1.15.8) were associated withan increased risk of cerebral palsy, but 57 of 78 (73%)children with cerebral palsy did not have either ofthese abnormalities. There was no association be-tween the highest or lowest FHR recorded for eachchild and the risk of cerebral palsy. The 21 childrenwith cerebral palsy who had multiple late decelera-tions or decreased FHR variability on EFM repre-sented only 0.2% of singleton infants with birthweights greater than 2,500 g who had these EFMfindings, for a false-positive rate of 99.8%. Theseauthors concluded that specific abnormal findings onEFM were associated with an increased risk of cere-bral palsy, but the false-positive rate was so high that,if these findings were used as an indication forcesarean delivery, many cesareans would have beenperformed without benefit but with the potential forharm. Of interest is the fact that the mothers of almost10% of infants with cerebral palsy did not go intolabor before delivery by cesarean.

In letters to the editor after the publication ofNelsons study in 1996,8 some refused to believe thatEFM could not do a better job of identifying fetusesthat developed brain injury. A pioneer of FHR mon-itoring and one of the developers of the nonstresstest,39 the most widely used test of antenatal fetalwell-being, argued that the data presented by Nelsonet al were derived from 10-year-old interpretations ofFHR patterns by diverse practitioners and failed totake into account newer insights into the relation offetal behavior and neurologic injury to FHR patternsthat had come to light over the previous decade(Schifrin BS, Myers SA, Cohen WR. Electronic fetalmonitoring in predicting cerebral palsy [letter].N Engl J Med 1996;335:287; [author reply] 288.). Thiscritique of Nelsons study also stated that it mademore sense to advocate greater discrimination in theevaluation of FHR patterns and not be so focused on

the cesarean delivery rate. They felt that FHR pat-terns may indeed permit an understanding of thetiming, mechanism, and preventability of injury andthus help in the planning of strategies for the preven-tion of cerebral palsy. Ironically, this pioneer in FHRmonitoring ultimately became a well-known expertwitness in medical malpractice cases and established alucrative consulting business that he named BPM(Beats Per Minute) after the EFM findings that areusually at the heart of these cases. In a 1985 article, hewrote that a court might well decide that the wide-spread utilization of EFM in low risk patients and theargument for (electronic) monitoring and against aus-cultation is so compelling that the ACOG and Na-tional Institute of Child Health and Human Develop-ment (NICHD) allowances (for auscultation) in thelow risk patient are improper.40

Although the cesarean delivery rate has increasedfrom 5% before the introduction of EFM to almost25% today, the incidence of cerebral palsy in terminfants has remained unchanged at 12 in 1,000births.41 Cesarean delivery during active labor, whichmay be performed on the basis of intrapartum EFMabnormalities, has been associated with an increasedrisk of hemorrhage, infection, thromboembolicevents, and air or amniotic-fluid embolization.42,43

Long-term complications of cesarean delivery includean increased rate of placenta accreta and uterinerupture. When comparing the occurrence rates ofcerebral palsy in nations with a broad range ofcesarean rates (722%), the reported cerebral palsyrates in all countries are within a very narrow range of1.11.3 of 1,000 in neonatal survivors with birthweights greater than 2,500 g.44 Electronic fetal moni-toring was developed to detect intrapartum asphyxialeading to cerebral palsy or death, and early studies asEFM was being developed assumed that half of allthese injuries were related to intrapartum hypoxia.Later studies from multiple centers around the worldhave shown that, at most, 1020% of cases of cerebralpalsy in term infants are related to intrapartum hyp-oxia.45,46 The prevalence of the target disorder forEFM, cerebral palsy related to intrapartum asphyxia,is much lower than the overall prevalence of cerebralpalsy. Because the amount of asphyxia required tocause permanent neurological damage is very nearthe amount that causes fetal death, the number ofpatients who develop cerebral palsy caused by intra-partum asphyxia is probably quite small.47 Unfortu-nately, debates as to whether intrapartum asphyxiacaused a childs neurological disability usually takeplace in the courtroom.

The most obvious problem with EFM is the wide


variability with which obstetricians interpret and re-spond to its findings. Numerous studies have docu-mented the poor inter- and intraobserver reliabilityfor the interpretation of FHR tracings. When fourobstetricians reviewed 50 FHR tracings twice, only22% were assessed identically by all four obstetricianson both occasions when trying to identify compro-mised infants, which made up a third of the studypopulation.48 At the time of the second review 2months later, the same clinicians interpreted 21% ofthe tracings differently, showing poor intraobserverreliability. A study in which five obstetricians inde-pendently reviewed 150 tracings found that theyagreed in only 29% of the cases, showing poorinterobserver reliability.49 Some investigators havestated that the failure of the randomized controlledtrials to identify a benefit for EFM is related to thelack of standard definitions or management algo-rithms for FHR interpretation, leading to wide vari-ability in clinical decision making. This deficiency isthought by some to have confounded the randomizedtrial method, suggesting that randomized trials shouldnot be considered as grade I evidence.50 It was hopedthat, if the obstetric community standardized FHRpattern interpretation and recommendations for man-agement, with such algorithms being just as specific asthe definitions of FHR patterns, then maybe a bene-ficial effect of EFM could be demonstrated.51 BetweenMay 1995 and November 1996, the NICHD heldresearch planning workshops to develop standardizedand unambiguous definitions for fetal heart rate trac-ings.52 The nationally prominent experts on thispanel, all of whom had published literature on thistopic, were able to reach agreement on what consti-tutes a reassuring FHR tracing. They were able toagree on several patterns, such as recurrent late orvariable decelerations, substantial bradycardia, andabsent FHR variability, which are predictive of cur-rent or impending fetal asphyxia so severe that thefetus is at risk for neurologic and other fetal damageor death. However, they acknowledged that manyfetuses have FHR tracings intermediate between thesetwo extremes and that their presumed condition andclinical management was controversial. There was noconsensus within the research workshop regardingstrict guidelines for clinical management using FHRpatterns. It was hoped that the strict definitions forFHR patterns that they had developed could be usedto devise evidence-based algorithms for managementthat would minimize risky interventions and reducesignificant metabolic acidemia.

To determine if the new NICHD research guide-lines for interpretation of FHR tracings could help us

better identify fetuses at risk for neurologic morbidity,we performed a case-control study of 150 consecutiveneonates with ultrasonographically diagnosed cere-bral white matter injury matched by gestational age to150 controls with normal head ultrasonograms (Table1).9 We chose to look at infants with white matterinjury because this diagnosis can be made within 6weeks of birth, unlike the diagnosis of cerebral palsy,which is not established until 12 years of life, poten-tially introducing many confounding factors, andbecause of the susceptibility of white matter to hyp-oxia and ischemia. These infants were all born at2334 weeks of gestation in a single institution be-tween 1994 and 2001. We were able to obtain theFHR tracings for 125 cases (83%) and 121 controls(81%). The last hour of the FHR tracing beforedelivery was reviewed by three perinatologistsblinded to outcome. Vaginal and cesarean deliverieswere analyzed separately. There was no difference inbaseline heart rate, tachycardia, bradycardia, short-term variability, accelerations, reactivity, or numberor types of decelerations between cases and controlsin either the vaginal or cesarean delivery groups. Inthe vaginal delivery group, the last 1618 minutes ofthe FHR tracing was uninterpretable due to difficultyin tracing the fetal heart with the fetal head low in thebirth canal just before delivery. For the six infants inthis study with an umbilical arterial pH less than 7.0or base excess less than 12 mM, metabolic acidosissevere enough to increase the risk of long-term neu-rologic morbidity, there was a significant increase indecreased short-term variability, but the positive pre-dictive value in identifying severe metabolic acidosiswas only 7.7% in this matched case-control popula-tion, which artificially enhances predictiveness by notincluding all normal infants. There was a significantcorrelation between an increasing number of latedecelerations during the last hour before delivery anddecreasing umbilical arterial base excess (r0.18,P.01), but the number of late decelerations per hourwas not significantly different between the severeacidosis and control groups (1.01.8 acidosis,0.551.23 controls, P.39). Even with the use of theNICHD research guidelines for interpretation of EFMtracings, we were unable to use EFM findings toidentify infants diagnosed with cerebral white matterinjury within 6 weeks of birth, a major precursor ofcerebral palsy.

It has been stated that computerized evaluation ofFHR tracings would solve the interpretive problemsproduced by observer inconsistency. It was hopedthat computer assistance in the quantitative process-ing of FHR baseline, variation, and event recognition


would bring us one step closer to eliminating theapparently insurmountable problem of observer reli-ability and reproducibility. Computerized FHR anal-ysis was introduced into routine clinical use in Ox-ford, United Kingdom, in 1983 when it was shownthat small computers could provide an objectiveanalysis of the FHR tracing.53 These investigatorsconcluded that measurement by a computer offersreliable objective information, from which fetal healthmay be assessed more objectively and accurately thanby visual inspection. A prospective observationalstudy conducted in eight tertiary medical centers inEurope and Australia of 345 women not in laborscheduled for elective cesarean delivery, whose lastFHR tracing was performed within 4 hours of deliv-ery, found that computerized quantification of accel-erations and variability in the antepartum periodallowed a good prediction of 1- and 5-minute Apgarscores but was not very predictive of umbilical arterypH.54 A study of 51 term laboring women concludedthat computer-derived FHR parameters studied dur-ing the last hour of labor did not correlate with thedegree of metabolic acidosis as measured in theumbilical artery at birth.55 At this time computerizedanalysis of FHR tracings has failed to gain clinicalacceptance because of its inability to identify thehypoxic-ischemic fetus.

CONCLUSIONVirtually all professional obstetric organizations be-lieve that some form of monitoring is necessaryduring labor although there are no trials comparingeither intermittent auscultation or EFM with no mon-itoring at all.47 The American College of Obstetriciansand Gynecologists has concluded that EFM does notoffer any advantage over intermittent auscultation.56

The false-positive rate of EFM in predicting adverseoutcomes is high, and the use of EFM does not resultin a reduction of cerebral palsy rates.37 Intermittentauscultation requires a 1:1 nurse to patient ratio andmust be performed at specific intervals. Logistically, itis difficult to adhere to the ACOG guidelines forintermittent auscultation. One prospective studynoted that the protocol for intermittent auscultationwas successfully completed in only 3% of cases.57

Because of the difficulty and expense of performingintermittent auscultation with 1:1 nursing, EFM con-tinues to be the most widely used method of moni-toring the intrapartum fetus. Both ACOG and theSociety of Obstetricians and Gynaecologists of Can-ada recommend some form of monitoring duringlabor, and EFM is easier, cheaper, and provides moredata. During the first randomized controlled trial of

EFM, the investigators noted the rise in cesareandeliveries, and at the conclusion of the study they feltthat 2 of 18 (6%) cesareans done for fetal distress inthe EFM group would not have been done at the timethey submitted their manuscript based on newerknowledge of FHR patterns.23 They acknowledgedthat, based on measured infant outcome, some oftheir cesarean deliveries were unnecessary. Thisshows that EFM was being widely used as an indica-tion for delivery before enough information wasavailable to adequately interpret the results. Somehave argued that the randomized controlled trialswere conducted before the technology was suffi-ciently developed and that its true benefit was under-valued,58 but even with the introduction of specificguidelines for interpreting FHR tracings issued by theNICHD, inter- and intraobserver consistency remainspoor, and we have still been unable to use EFM toidentify the fetus at risk for neurologic morbidity.9

Since the introduction of EFM, there has been arapid increase in litigation claiming negligent injury tothe fetus during labor. Often the allegation of medicalmalpractice is based on the failure to perform acesarean delivery in a timely fashion in the face ofabnormal FHR patterns. Because EFM was intro-duced without agreed upon definitions for interpreta-tion and management algorithms, expert witnessesretained by the opposing sides in a trial can deliververy different interpretations of the same FHR tracingin the courtroom to the confusion and frustration oflay juries. In these trials many plaintiffs experts claimto be able to do what scientific medicine has beenunable to accomplish: to identify precisely that pointat which the fetus sustained irreparable brain dam-age.20 The benefits now claimed by the advocates ofEFM are clearly more modest than originally pro-posed and appear to be primarily in the prevention ofneonatal seizures, but since this increase in neonatalseizures has not been found to be associated with anincreased risk of long-term neurologic morbidity andsince the increase in operative deliveries puts themother at some increased risk, no advantage has beenproven for EFM.5 Because of the inability of EFM toidentify the truly hypoxic-ischemic fetus, a joint com-mittee from ACOG and the American Academy ofPediatrics has encouraged further research into othermethods of intrapartum fetal evaluation.59 Fetal pulseoximetry and fetal electrocardiogram wave form anal-ysis show the most promise for improving our abilityto identify the hypoxic-ischemic fetus. Both of thesemethods are being subjected to randomized con-trolled trials before their widespread introduction intoclinical practice, unlike the case with EFM. In the first


randomized controlled trial involving fetal ST wave-form analysis, published in 1993, the authors statedthat they believed that this is the first time a newconcept for fetal assessment that involves new tech-nology has been tested in a randomized trial beforewidespread introduction into obstetric practice.60 Af-ter the first randomized controlled trial of fetal pulseoximetry failed to show a decrease in the overallcesarean rate,61 the ACOG Committee on ObstetricPractice stated that they could not endorse the adop-tion of this device at the present time because itsintroduction into widespread clinical practice couldfurther escalate the cost of medical care withoutnecessarily improving clinical outcome.62 This showsthat any new intrapartum monitoring modality will besubjected to a much greater degree of scrutiny thanoccurred in the past with EFM.

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