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Review
. 2017 Feb 3;2(2):CD006066.
doi: 10.1002/14651858.CD006066.pub3.

Continuous Cardiotocography (CTG) as a Form of Electronic Fetal Monitoring (EFM) for Fetal Assessment During Labour

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Free PMC article
Review

Continuous Cardiotocography (CTG) as a Form of Electronic Fetal Monitoring (EFM) for Fetal Assessment During Labour

Zarko Alfirevic et al. Cochrane Database Syst Rev. .
Free PMC article

Abstract

Background: Cardiotocography (CTG) records changes in the fetal heart rate and their temporal relationship to uterine contractions. The aim is to identify babies who may be short of oxygen (hypoxic) to guide additional assessments of fetal wellbeing, or determine if the baby needs to be delivered by caesarean section or instrumental vaginal birth. This is an update of a review previously published in 2013, 2006 and 2001.

Objectives: To evaluate the effectiveness and safety of continuous cardiotocography when used as a method to monitor fetal wellbeing during labour.

Search methods: We searched the Cochrane Pregnancy and Childbirth Group Trials Register (30 November 2016) and reference lists of retrieved studies.

Selection criteria: Randomised and quasi-randomised controlled trials involving a comparison of continuous cardiotocography (with and without fetal blood sampling) with no fetal monitoring, intermittent auscultation intermittent cardiotocography.

Data collection and analysis: Two review authors independently assessed study eligibility, quality and extracted data from included studies. Data were checked for accuracy.

Main results: We included 13 trials involving over 37,000 women. No new studies were included in this update.One trial (4044 women) compared continuous CTG with intermittent CTG, all other trials compared continuous CTG with intermittent auscultation. No data were found comparing no fetal monitoring with continuous CTG. Overall, methodological quality was mixed. All included studies were at high risk of performance bias, unclear or high risk of detection bias, and unclear risk of reporting bias. Only two trials were assessed at high methodological quality.Compared with intermittent auscultation, continuous cardiotocography showed no significant improvement in overall perinatal death rate (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.59 to 1.23, N = 33,513, 11 trials, low quality evidence), but was associated with halving neonatal seizure rates (RR 0.50, 95% CI 0.31 to 0.80, N = 32,386, 9 trials, moderate quality evidence). There was no difference in cerebral palsy rates (RR 1.75, 95% CI 0.84 to 3.63, N = 13,252, 2 trials, low quality evidence). There was an increase in caesarean sections associated with continuous CTG (RR 1.63, 95% CI 1.29 to 2.07, N = 18,861, 11 trials, low quality evidence). Women were also more likely to have instrumental vaginal births (RR 1.15, 95% CI 1.01 to 1.33, N = 18,615, 10 trials, low quality evidence). There was no difference in the incidence of cord blood acidosis (RR 0.92, 95% CI 0.27 to 3.11, N = 2494, 2 trials, very low quality evidence) or use of any pharmacological analgesia (RR 0.98, 95% CI 0.88 to 1.09, N = 1677, 3 trials, low quality evidence).Compared with intermittent CTG, continuous CTG made no difference to caesarean section rates (RR 1.29, 95% CI 0.84 to 1.97, N = 4044, 1 trial) or instrumental births (RR 1.16, 95% CI 0.92 to 1.46, N = 4044, 1 trial). Less cord blood acidosis was observed in women who had intermittent CTG, however, this result could have been due to chance (RR 1.43, 95% CI 0.95 to 2.14, N = 4044, 1 trial).Data for low risk, high risk, preterm pregnancy and high-quality trials subgroups were consistent with overall results. Access to fetal blood sampling did not appear to influence differences in neonatal seizures or other outcomes.Evidence was assessed using GRADE. Most outcomes were graded as low quality evidence (rates of perinatal death, cerebral palsy, caesarean section, instrumental vaginal births, and any pharmacological analgesia), and downgraded for limitations in design, inconsistency and imprecision of results. The remaining outcomes were downgraded to moderate quality (neonatal seizures) and very low quality (cord blood acidosis) due to similar concerns over limitations in design, inconsistency and imprecision.

Authors' conclusions: CTG during labour is associated with reduced rates of neonatal seizures, but no clear differences in cerebral palsy, infant mortality or other standard measures of neonatal wellbeing. However, continuous CTG was associated with an increase in caesarean sections and instrumental vaginal births. The challenge is how best to convey these results to women to enable them to make an informed decision without compromising the normality of labour.The question remains as to whether future randomised trials should measure efficacy (the intrinsic value of continuous CTG in trying to prevent adverse neonatal outcomes under optimal clinical conditions) or effectiveness (the effect of this technique in routine clinical practice).Along with the need for further investigations into long-term effects of operative births for women and babies, much remains to be learned about the causation and possible links between antenatal or intrapartum events, neonatal seizures and long-term neurodevelopmental outcomes, whilst considering changes in clinical practice over the intervening years (one-to-one-support during labour, caesarean section rates). The large number of babies randomised to the trials in this review have now reached adulthood and could potentially provide a unique opportunity to clarify if a reduction in neonatal seizures is something inconsequential that should not greatly influence women's and clinicians' choices, or if seizure reduction leads to long-term benefits for babies. Defining meaningful neurological and behavioural outcomes that could be measured in large cohorts of young adults poses huge challenges. However, it is important to collect data from these women and babies while medical records still exist, where possible describe women's mobility and positions during labour and birth, and clarify if these might impact on outcomes. Research should also address the possible contribution of the supine position to adverse outcomes for babies, and assess whether the use of mobility and positions can further reduce the low incidence of neonatal seizures and improve psychological outcomes for women.

Conflict of interest statement

Zarko Alfirevic (ZA) is Director of Harris Wellbeing Preterm Birth Centre which is grant funded by the charity Wellbeing of Women. This grant is administered by University of Liverpool and Zarko Alfirevic is not paid directly. He is the principal investigator or co‐investigator on several grants from public funders including National Institute of Health Research, British Medical Association, European Commission and WHO. He has received research support in the past from Perkin Elmer and Alere for research related to pre‐eclampsia and preterm birth prevention. These grants were administered by his employers and ZA did not benefit directly. ZA is also a Co‐coordinating Editor of Cochrane Pregnancy and Childbirth.

Declan Devane has conducted a trial, known as the ADCAR Trial, evaluating the effectiveness of the admission cardiotocograph (CTG) compared with intermittent auscultation. This study is funded by the Health Research Board (Ireland). If this trial is eligible for inclusion in the full review, or a subsequent review update, the investigators will not be involved in assessing the trial for inclusion, assessing risk of bias, or data extraction. These tasks will be carried out by two other members of the review team who are not directly involved with the ADCAR Trial.

Gillian ML Gyte has received royalties from John Wiley & Son in respect of ‘A Cochrane Pocket Handbook – Pregnancy and Childbirth’ Hofmeyr GJ et al. 2008.

Anna Cuthbert: I am a research associate working in the editorial base of Cochrane Pregnancy and Childbirth. I am employed by the University of Liverpool to work as a research assistant in Cochrane Pregnancy and Childbirth (who receives infrastructure funding from the NIHR, UK).

Figures

Figure 1
Figure 1
Methodological quality summary: review authors' judgements about each methodological quality item for each included study
Figure 2
Figure 2
Funnel plot of comparison: 1 Continuous CTG versus intermittent auscultation, outcome: 1.1 Perinatal mortality (main outcome)
Figure 3
Figure 3
Funnel plot of comparison: 1 Continuous CTG versus intermittent auscultation, outcome: 1.2 Neonatal seizures (main outcome)
Figure 4
Figure 4
Funnel plot of comparison: 1 Continuous CTG versus intermittent auscultation, outcome: 1.4 Caesarean section (main outcome)
Figure 5
Figure 5
Funnel plot of comparison: 1 Continuous CTG versus intermittent auscultation, outcome: 1.5 Instrumental vaginal birth (main outcome)
Analysis 1.1
Analysis 1.1
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 1 Perinatal mortality (main outcome).
Analysis 1.2
Analysis 1.2
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 2 Neonatal seizures (main outcome).
Analysis 1.3
Analysis 1.3
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 3 Cerebral palsy (main outcome).
Analysis 1.4
Analysis 1.4
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 4 Caesarean section (main outcome).
Analysis 1.5
Analysis 1.5
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 5 Instrumental vaginal birth (main outcome).
Analysis 1.6
Analysis 1.6
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 6 Cord blood acidosis (main outcome).
Analysis 1.7
Analysis 1.7
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 7 Any pharmacological analgesia (main outcome).
Analysis 1.8
Analysis 1.8
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 8 Hypoxic ischaemic encephalopathy.
Analysis 1.9
Analysis 1.9
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 9 Neurodevelopmental disability at at least 12 months of age.
Analysis 1.10
Analysis 1.10
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 10 Apgar score < 7 at 5 minutes.
Analysis 1.11
Analysis 1.11
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 11 Apgar score < 4 at 5 minutes.
Analysis 1.12
Analysis 1.12
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 12 Neonatal ICU admissions.
Analysis 1.13
Analysis 1.13
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 13 Fetal blood sampling.
Analysis 1.14
Analysis 1.14
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 14 Damage/infection from scalp electrode or scalp sampling.
Analysis 1.15
Analysis 1.15
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 15 Caesarean section for abnormal FHR pattern and/or acidosis.
Analysis 1.16
Analysis 1.16
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 16 Instrumental vaginal birth for abnormal CTG or fetal acidosis.
Analysis 1.17
Analysis 1.17
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 17 Spontaneous vaginal birth.
Analysis 1.18
Analysis 1.18
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 18 Epidural analgesia.
Analysis 1.19
Analysis 1.19
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 19 Oxytocin during 1st and/or 2nd stage of labour.
Analysis 1.20
Analysis 1.20
Comparison 1 Continuous CTG versus intermittent auscultation, Outcome 20 Length of stay on NICU.
Analysis 2.1
Analysis 2.1
Comparison 2 Continuous CTG versus IA (pregnancy risk status ‐ high/low), Outcome 1 Perinatal mortality.
Analysis 2.2
Analysis 2.2
Comparison 2 Continuous CTG versus IA (pregnancy risk status ‐ high/low), Outcome 2 Neonatal seizures.
Analysis 2.3
Analysis 2.3
Comparison 2 Continuous CTG versus IA (pregnancy risk status ‐ high/low), Outcome 3 Cerebral palsy.
Analysis 2.4
Analysis 2.4
Comparison 2 Continuous CTG versus IA (pregnancy risk status ‐ high/low), Outcome 4 Caesarean section.
Analysis 2.5
Analysis 2.5
Comparison 2 Continuous CTG versus IA (pregnancy risk status ‐ high/low), Outcome 5 Instrumental vaginal birth.
Analysis 2.6
Analysis 2.6
Comparison 2 Continuous CTG versus IA (pregnancy risk status ‐ high/low), Outcome 6 Cord blood acidosis.
Analysis 2.7
Analysis 2.7
Comparison 2 Continuous CTG versus IA (pregnancy risk status ‐ high/low), Outcome 7 Any pharmacological analgesia.
Analysis 3.1
Analysis 3.1
Comparison 3 Continuous CTG versus IA (onset of labour ‐ spontaneous/induced), Outcome 1 Perinatal mortality.
Analysis 3.2
Analysis 3.2
Comparison 3 Continuous CTG versus IA (onset of labour ‐ spontaneous/induced), Outcome 2 Neonatal seizures.
Analysis 3.3
Analysis 3.3
Comparison 3 Continuous CTG versus IA (onset of labour ‐ spontaneous/induced), Outcome 3 Cerebral palsy.
Analysis 3.4
Analysis 3.4
Comparison 3 Continuous CTG versus IA (onset of labour ‐ spontaneous/induced), Outcome 4 Caesarean section.
Analysis 3.5
Analysis 3.5
Comparison 3 Continuous CTG versus IA (onset of labour ‐ spontaneous/induced), Outcome 5 Instrumental vaginal birth.
Analysis 3.6
Analysis 3.6
Comparison 3 Continuous CTG versus IA (onset of labour ‐ spontaneous/induced), Outcome 6 Cord blood acidosis.
Analysis 3.7
Analysis 3.7
Comparison 3 Continuous CTG versus IA (onset of labour ‐ spontaneous/induced), Outcome 7 Any pharmacological analgesia.
Analysis 4.1
Analysis 4.1
Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 1 Perinatal mortality.
Analysis 4.2
Analysis 4.2
Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 2 Neonatal seizures.
Analysis 4.3
Analysis 4.3
Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 3 Cerebral palsy.
Analysis 4.4
Analysis 4.4
Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 4 Caesarean section.
Analysis 4.5
Analysis 4.5
Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 5 Instrumental vaginal birth.
Analysis 4.6
Analysis 4.6
Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 6 Cord blood acidosis.
Analysis 4.7
Analysis 4.7
Comparison 4 Continuous CTG versus IA (preterm/term labour), Outcome 7 Any pharmacological analgesia.
Analysis 5.1
Analysis 5.1
Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 1 Perinatal mortality.
Analysis 5.2
Analysis 5.2
Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 2 Neonatal seizures.
Analysis 5.3
Analysis 5.3
Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 3 Cerebral palsy.
Analysis 5.4
Analysis 5.4
Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 4 Caesarean section.
Analysis 5.5
Analysis 5.5
Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 5 Instrumental vaginal birth.
Analysis 5.6
Analysis 5.6
Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 6 Cord blood acidosis.
Analysis 5.7
Analysis 5.7
Comparison 5 Continuous CTG versus IA (singleton/twin pregnancy), Outcome 7 Any pharmacological analgesia.
Analysis 6.1
Analysis 6.1
Comparison 6 Continuous CTG versus IA (access to FBS during labour ‐ yes/no), Outcome 1 Perinatal mortality.
Analysis 6.2
Analysis 6.2
Comparison 6 Continuous CTG versus IA (access to FBS during labour ‐ yes/no), Outcome 2 Neonatal seizures.
Analysis 6.3
Analysis 6.3
Comparison 6 Continuous CTG versus IA (access to FBS during labour ‐ yes/no), Outcome 3 Cerebral palsy.
Analysis 6.4
Analysis 6.4
Comparison 6 Continuous CTG versus IA (access to FBS during labour ‐ yes/no), Outcome 4 Caesarean section.
Analysis 6.5
Analysis 6.5
Comparison 6 Continuous CTG versus IA (access to FBS during labour ‐ yes/no), Outcome 5 Instrumental vaginal birth.
Analysis 6.6
Analysis 6.6
Comparison 6 Continuous CTG versus IA (access to FBS during labour ‐ yes/no), Outcome 6 Cord blood acidosis.
Analysis 6.7
Analysis 6.7
Comparison 6 Continuous CTG versus IA (access to FBS during labour ‐ yes/no), Outcome 7 Any pharmacological analgesia.
Analysis 7.1
Analysis 7.1
Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 1 Perinatal mortality.
Analysis 7.2
Analysis 7.2
Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 2 Neonatal seizures.
Analysis 7.3
Analysis 7.3
Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 3 Cerebral palsy.
Analysis 7.4
Analysis 7.4
Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 4 Caesarean section.
Analysis 7.5
Analysis 7.5
Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 5 Instrumental vaginal birth.
Analysis 7.6
Analysis 7.6
Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 6 Cord blood acidosis.
Analysis 7.7
Analysis 7.7
Comparison 7 Continuous CTG versus IA (primiparous/multiparous women), Outcome 7 Any pharmacological analgesia.
Analysis 8.1
Analysis 8.1
Comparison 8 Continuous CTG versus IA (sensitivity analysis: high and low quality studies), Outcome 1 Perinatal mortality.
Analysis 8.2
Analysis 8.2
Comparison 8 Continuous CTG versus IA (sensitivity analysis: high and low quality studies), Outcome 2 Neonatal seizures.
Analysis 8.3
Analysis 8.3
Comparison 8 Continuous CTG versus IA (sensitivity analysis: high and low quality studies), Outcome 3 Cerebral palsy.
Analysis 8.4
Analysis 8.4
Comparison 8 Continuous CTG versus IA (sensitivity analysis: high and low quality studies), Outcome 4 Caesarean section.
Analysis 8.5
Analysis 8.5
Comparison 8 Continuous CTG versus IA (sensitivity analysis: high and low quality studies), Outcome 5 Instrumental vaginal birth.
Analysis 8.6
Analysis 8.6
Comparison 8 Continuous CTG versus IA (sensitivity analysis: high and low quality studies), Outcome 6 Cord blood acidosis.
Analysis 8.7
Analysis 8.7
Comparison 8 Continuous CTG versus IA (sensitivity analysis: high and low quality studies), Outcome 7 Any pharmacological analgesia.
Analysis 9.1
Analysis 9.1
Comparison 9 Continuous CTG versus intermittent CTG, Outcome 1 Caesarean section (main outcome).
Analysis 9.2
Analysis 9.2
Comparison 9 Continuous CTG versus intermittent CTG, Outcome 2 Instrumental vaginal birth (main outcome).
Analysis 9.3
Analysis 9.3
Comparison 9 Continuous CTG versus intermittent CTG, Outcome 3 Cord blood acidosis (main outcome).
Analysis 9.4
Analysis 9.4
Comparison 9 Continuous CTG versus intermittent CTG, Outcome 4 Apgar score < 7 at 5 minutes.
Analysis 9.5
Analysis 9.5
Comparison 9 Continuous CTG versus intermittent CTG, Outcome 5 Neonatal ICU admissions.
Analysis 9.6
Analysis 9.6
Comparison 9 Continuous CTG versus intermittent CTG, Outcome 6 Caesarean section for abnormal FHR pattern and/or acidosis.
Analysis 9.7
Analysis 9.7
Comparison 9 Continuous CTG versus intermittent CTG, Outcome 7 Spontaneous vaginal birth.
Analysis 9.8
Analysis 9.8
Comparison 9 Continuous CTG versus intermittent CTG, Outcome 8 Epidural analgesia.

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