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Fetal electrocardiogram (ECG) for fetal monitoring during labour

  1. James P Neilson*

Editorial Group: Cochrane Pregnancy and Childbirth Group

Published Online: 31 MAY 2013

Assessed as up-to-date: 12 FEB 2013

DOI: 10.1002/14651858.CD000116.pub4


How to Cite

Neilson JP. Fetal electrocardiogram (ECG) for fetal monitoring during labour. Cochrane Database of Systematic Reviews 2013, Issue 5. Art. No.: CD000116. DOI: 10.1002/14651858.CD000116.pub4.

Author Information

  1. The University of Liverpool, Department of Women's and Children's Health, Liverpool, UK

*James P Neilson, Department of Women's and Children's Health, The University of Liverpool, First Floor, Liverpool Women's NHS Foundation Trust, Crown Street, Liverpool, L8 7SS, UK. jneilson@liverpool.ac.uk.

Publication History

  1. Publication Status: New search for studies and content updated (no change to conclusions)
  2. Published Online: 31 MAY 2013

SEARCH

 

Background

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms

Labour poses a potential threat to fetal wellbeing. The supply of oxygen to the fetus requires an adequate supply of maternal blood to the placenta, a properly functioning placenta to allow transfer of oxygen from maternal to fetal blood, and a patent umbilical vein in the umbilical cord to the fetus. Strong uterine contractions in labour stop the flow of maternal blood to the placenta with intermittent decreases in oxygenation. Most fetuses have sufficient metabolic reserve to withstand this effect but those with limited reserves, notably malnourished 'growth restricted' fetuses, may become distressed. The umbilical cord may also be compressed during labour, especially if the membranes are ruptured, which may also cause distress.

The earliest method of monitoring fetal wellbeing during labour was by using the fetal (Pinard) stethoscope intermittently to calculate the fetal heart rate. During the 1960s and 1970s, electronic systems were developed to allow monitoring of the fetal heart rate together with the mother's uterine contractions (cardiotocography), and these have been very widely used. To monitor the heart rate, signals can be obtained from an ultrasound transducer strapped to the mother's abdomen, or from an electrode clipped into the baby's scalp. Traces of the baby's heart rate may be 'continuous' (that is, throughout labour) or intermittent. Although the mother's mobility is limited by both methods, this is obviously greater with continuous monitoring. Non-reassuring features on a cardiotocography trace would include unusually rapid or slow rates, a flat pattern (reduced variability), and certain types of heart rate decelerations (especially 'late' or 'severe variable' decelerations). Such observations might prompt further intervention in the form of operative delivery, or additional testing of fetal condition (see below).

A systematic review of randomised trials comparing continuous electronic fetal heart rate monitoring (cardiotocography) and intermittent auscultation (Alfirevic 2006) showed fewer babies having neonatal convulsions after continuous monitoring (risk ratio (RR) 0.50, 95% confidence interval (CI) 0.31 to 0.80) but at the cost of increased rates of obstetric intervention in the form of caesarean section (RR 1.66, 95% CI 1.30 to 2.13) and instrumental vaginal delivery (RR 1.16, 95% CI 1.01 to 1.32). Neonatal convulsions are often, but not always, associated with hypoxic-ischaemic encephalopathy due to hypoxaemic brain damage and may be linked to subsequent neuro-developmental disability, including cerebral palsy. It should therefore be an important goal of obstetric care to avoid neonatal convulsions. However, it is also important to avoid unnecessary obstetric intervention.

Cardiotocographic traces may be difficult to interpret, resulting in unnecessary operative intervention, while some significant changes go unrecognised. Computerised cardiotocography has not proved helpful during labour (Dawes 1994). However, there is some evidence that fetal blood sampling, as an adjunctive test along with cardiotocography, may decrease unnecessary intervention without jeopardising fetal outcome. No clinical trials have directly compared fetal monitoring by cardiotocography alone versus cardiotocography with the option of fetal scalp sampling. However, trials comparing cardiotocography with intermittent auscultation show a greater increase in caesarean section rates when fetal scalp sampling was not available (RR 1.79, 95% CI 1.41 to 2.27) than when available (RR 1.26, 95% CI 1.05 to 1.51) (Alfirevic 2006). Scalp sampling is an awkward, uncomfortable procedure for the mother and involves a stab incision in the scalp of the fetus. This has limited its appeal and pre-empts its use in areas with a high prevalence of HIV infection. An additional drawback is that, by its nature, scalp sampling can only give intermittent information about fetal acid-base status.

To address these challenges in intrapartum fetal monitoring, technology has been developed to monitor the fetal electrocardiographic (ECG) waveform during labour. If shown helpful to either improve fetal outcome, or decrease unnecessary intervention, or both, this has the potential advantage of providing continuous information as well as being less invasive than fetal scalp sampling (although it is not non-invasive: requiring a signal obtained from an electrode embedded in the fetal scalp).

The fetal ECG, like the adult ECG, displays P, QRS, and T waves corresponding to electrical events in the heart during each beat. The P wave represents atrial contraction, QRS ventricular contraction, and T ventricular repolarisation. Two parts of the fetal ECG waveform have attracted attention from researchers: PR/RR relations and the ST waveform (Greene 1999). Normally there is a positive correlation between the PR interval (the time between the P wave and the R component of the QRS complex) and the RR interval, such that when the heart rate increases both PR and RR intervals shorten. In sheep experiments where the fetus was made hypoxaemic, a paradoxical effect was seen, in which the PR interval shortened despite lengthening of the RR interval ('bradycardia' or slowing of the heart rate). This led to the hypothesis that measurement of PR/RR relations might help distinguish between hypoxaemic and (less worrying) non-hypoxaemic decelerations of the human fetal heart rate during labour, thus refining assessment of fetal wellbeing.

Repolarisation of myocardial (heart muscle) cells is very sensitive to metabolic dysfunction, and may be reflected in changes of the ST waveform. Thus, in adults with myocardial infarction or exercise-induced angina pectoris from coronary artery disease, the ST segment may be elevated. Similar findings may be seen in fetal sheep under experimental conditions of moderate to severe hypoxaemia with an elevation of the ST segment and the T wave (Greene 1987). This change can be expressed as a ratio of T wave height to QRS height: the T/QRS ratio. Testing of a microprocessor-based system (Rosen 1989) in observational studies in humans suggested that assessment of a combination of fetal heart rate and ST waveform changes may be clinically useful (Rosen 1991).

 

Objectives

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms

To compare the effects of analysis of fetal electrocardiogram waveforms during labour with alternative methods of fetal monitoring.

 

Methods

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms
 

Criteria for considering studies for this review

 

Types of studies

Randomised controlled trials that compare analysis of any component of the fetal electrocardiographic (ECG) during labour with alternative fetal monitoring methods. Studies using less robust methods of allocation (for example, alternation) were not included.

 

Types of participants

Pregnant women (and their fetuses) in labour, with a perceived need for continuous electronic fetal heart rate monitoring (for reasons, see Characteristics of included studies table).

 

Types of interventions

Any type of fetal electrocardiographic waveform analysis, alone or in combination with another method of fetal assessment.

 

Types of outcome measures

 

Primary outcomes

 
Maternal

  • Caesarean section

 
Fetal

  • Cord artery pH less than 7.05 and base deficit greater than 12 mmol/L (blood)
  • Neonatal encephalopathy

 

Secondary outcomes

 
Maternal

  • Fetal blood sampling
  • Operative vaginal delivery

 
Fetal

  • Apgar score less than seven at five minutes
  • Neonatal intubation
  • Admission to neonatal special care unit
  • Perinatal death
  • Cerebral palsy

 

Search methods for identification of studies

 

Electronic searches

The Trials Search Co-ordinator searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (12 February 2013). 

The Cochrane Pregnancy and Childbirth Group’s Trials Register is maintained by the Trials Search Co-ordinator and contains trials identified from: 

  1. monthly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);
  2. weekly searches of MEDLINE;
  3. weekly searches of EMBASE;
  4. handsearches of 30 journals and the proceedings of major conferences;
  5. weekly current awareness alerts for a further 44 journals plus monthly BioMed Central email alerts.

Details of the search strategies for CENTRAL, MEDLINE and EMBASE, the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service can be found in the ‘Specialized Register’ section within the editorial information about the Cochrane Pregnancy and Childbirth Group

Trials identified through the searching activities described above are each assigned to a review topic (or topics). The Trials Search Co-ordinator searches the register for each review using the topic list rather than keywords.  

No language restrictions were applied.

 

Data collection and analysis

For the methods used when assessing the trials identified in the previous version of this review, see Appendix 1.

No new trials were identified for this update (2013). The following methods were used for the 2011 and 2012 updates and will be used in future updates.

 

Selection of studies

Jim Neilson (JPN) assessed for inclusion all the potential studies identified as a result of the search strategy.

 

Data extraction and management

A form was designed to extract data. For eligible studies, JPN extracted the data using the agreed form. Data were entered into Review Manager software (RevMan 2011) and checked for accuracy.

When information regarding any of the above was unclear, JPN contacted the authors of the original reports to provide further details.

 

Assessment of risk of bias in included studies

The risk of bias for each study was assessed by JPN, using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011).

 

(1) Sequence generation (checking for possible selection bias)

For each included study the method used to generate the allocation sequence is described in sufficient detail to allow an assessment of whether it should produce comparable groups.

The methods were assessed as:

  • low risk (any truly random process, e.g. random number table; computer random number generator);
  • high risk (any non random process, e.g. odd or even date of birth; hospital or clinic record number);
  • unclear.   

 

(2) Allocation concealment (checking for possible selection bias)

For each included study the method used to conceal the allocation sequence is described to determine whether intervention allocation could have been foreseen in advance of, or during recruitment, or changed after assignment.

The methods were assessed as:

  • low risk of bias (e.g. telephone or central randomisation; consecutively numbered sealed opaque envelopes);
  • high risk of bias (open random allocation; unsealed or non-opaque envelopes, alternation; date of birth);
  • unclear risk of bias.   

 

(3) Blinding (checking for possible performance bias)

For each included study the methods used, if any, to blind study participants and personnel from knowledge of which intervention a participant received are described. Studies were considered to be at low risk of bias if they were blinded, or it was judged that the lack of blinding could not have affected the results. Blinding was assessed separately for different outcomes or classes of outcomes.

The methods were assessed as:

  • low, high or unclear risk of bias for participants;
  • low, high or unclear risk of bias for personnel;
  • low, high or unclear risk of bias for outcome assessors.

 

(4) Incomplete outcome data (checking for possible attrition bias through withdrawals, dropouts, protocol deviations)

For each included study, and for each outcome or class of outcomes, the completeness of data including attrition and exclusions from the analysis is described, including whether attrition and exclusions were reported, the numbers included in the analysis at each stage (compared with the total randomised participants), reasons for attrition or exclusion where reported, and whether missing data were balanced across groups or were related to outcomes. Where sufficient information was reported, or supplied by the trial authors, this missing data was re-included in the analyses which were undertaken. The methods were assessed as:

  • low risk of bias (less than 20% missing data);
  • high risk of bias (greater than 20% missing data);
  • unclear risk of bias.

 

(5) Selective reporting bias

The review author describes for each included study how he investigated the possibility of selective outcome reporting bias and what he found.

The methods were assessed as:

  • low risk of bias (where it is clear that all of the study’s pre-specified outcomes and all expected outcomes of interest to the review have been reported);
  • high risk of bias (where not all the study’s pre-specified outcomes have been reported; one or more reported primary outcomes were not pre-specified; outcomes of interest are reported incompletely and so cannot be used; study fails to include results of a key outcome that would have been expected to have been reported);
  • unclear risk of bias.

 

(6) Other sources of bias

For each included study, the review author describes any important concerns about other possible sources of bias.

The review author assessed whether each study was free of other problems that could put it at risk of bias:

  • low risk of other bias;
  • high risk of other bias;
  • unclear whether there was risk of other bias.

 

(7) Overall risk of bias

The review author made explicit judgements about whether studies are at high risk of bias, according to the criteria given in the Handbook (Higgins 2011). With reference to (1) to (6) above, he assessed the likely magnitude and direction of the bias and whether he considered it likely to impact on the findings. In future updates, the impact of the level of bias will be explored through undertaking sensitivity analyses - see Sensitivity analysis

 

Measures of treatment effect

 

Dichotomous data

For dichotomous data, results are presented as summary risk ratio with 95% confidence intervals. 

 

Continuous data

No data were analysed as continuous data. In future updates, if appropriate, we will use the mean difference if outcomes are measured in the same way between trials. We will use the standardised mean difference to combine trials that measure the same outcome, but use different methods.

 

Unit of analysis issues

 

Cluster-randomised trials

Cluster-randomised trials will be included in the analyses along with individually-randomised trials. We will adjust their standard errors using the methods described in the Handbook using an estimate of the intracluster correlation co-efficient (ICC) derived from the trial (if possible), from a similar trial or from a study of a similar population. If ICCs are used from other sources, this will be reported and sensitivity analyses will be conducted to investigate the effect of variation in the ICC. If both cluster-randomised trials and individually-randomised trials are identified, the relevant information will be synthesised. It will be considered reasonable to combine the results from both if there is little heterogeneity between the study designs and the interaction between the effect of intervention and the choice of randomisation unit is considered to be unlikely.

Heterogeneity in the randomisation unit will be acknowledged and a sensitivity analysis will be performed to investigate the effects of the randomisation unit.

 

Cross-over trials

If, in future updates of this review, cross-over trials are identified on this topic, and such trials are deemed eligible for inclusion, they will be included in the analyses with parallel group trials, using methods described by Elbourne 2002

 

Dealing with missing data

For included studies, levels of attrition were noted. The impact of including studies with high levels of missing data in the overall assessment of treatment effect will be explored in future updates by using sensitivity analysis.

For all outcomes, analyses were carried out, as far as possible, on an intention-to-treat basis, i.e. the review author attempted to include all participants randomised to each group in the analyses, and all participants were analysed in the group to which they were allocated, regardless of whether or not they received the allocated intervention. The denominator for each outcome in each trial was the number randomised minus any participants whose outcomes were known to be missing.

 

Assessment of heterogeneity

Statistical heterogeneity was assessed in each meta-analysis using the T², I² and Chi² statistics. Heterogeneity was regarded as substantial if I² was greater than 30% and either T² was greater than zero, or there was a low P value (less than 0.10) in the Chi² test for heterogeneity. 

 

Assessment of reporting biases

If there were 10 or more studies in the meta-analysis, the review author planned to investigate reporting biases (such as publication bias) using funnel plots. In future updates, funnel plot asymmetry will be assessed visually. If asymmetry is suggested by a visual assessment, exploratory analyses were performed to investigate it.

 

Data synthesis

Statistical analysis was carried out using Review Manager software (RevMan 2011). Fixed-effect meta-analyses were used for combining data where it was reasonable to assume that studies were estimating the same underlying treatment effect: i.e. where trials were examining the same intervention, and the trials’ populations and methods were judged sufficiently similar. If there was clinical heterogeneity, sufficient to expect that the underlying treatment effects differed between trials, or if substantial statistical heterogeneity was detected, random-effects meta-analysis was used to produce an overall summary if an average treatment effect across trials was considered clinically meaningful. A random-effects summary was treated as the average range of possible treatment effects and the review author discusses the clinical implications of treatment effects differing between trials. If the average treatment effect was not clinically meaningful, trials were not combined.

Where random-effects analyses are used, the results are presented as the average treatment effect with its 95% confidence interval, and the estimates of  T² and I².

 

Subgroup analysis and investigation of heterogeneity

Subgroup analysis was not carried out.

The review author carried out separate comparisons for two subgroups: based on whether the technique trialled assessed PR/RR relations or the ST segment. All outcomes were assessed in both groups of comparisons.

 

Sensitivity analysis

In future updates of this review, sensitivity analyses will be performed to explore outcomes with statistical heterogeneity and the effects of any assumptions made such as the value of the ICC used for cluster-randomised trials (if appropriate).

 

Results

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms
 

Description of studies

Six trials were identified that fulfilled the criteria for inclusion: five based on ST analysis (UK, Sweden, France, Finland, Netherlands) and one on PR length (multi-national). See Characteristics of included studies.

 

Risk of bias in included studies

All trials employed adequate methods of allocation concealment.

 

Effects of interventions

Six trials (16,295 women) were included: five trials of ST waveform analysis (15,338 women) and one trial of PR interval analysis (957 women).

In comparison to continuous electronic fetal heart rate monitoring alone, the use of adjunctive ST waveform analysis made no significant difference to primary outcomes, namely births by caesarean section (risk ratio (RR) 0.99, 95% confidence interval (CI) 0.91 to 1.08),  Analysis 1.1, or the number of babies with severe metabolic acidosis at birth (cord arterial pH less than 7.05 and base deficit greater than 12 mmol/L) (RR 0.78, 95% CI 0.44 to 1.37, data from 14,574 babies),  Analysis 1.2, or babies with neonatal encephalopathy (RR 0.54, 95% CI 0.24 to 1.25),  Analysis 1.3.

As for secondary outcomes, there were on average fewer fetal scalp samples taken during labour (RR 0.61, 95% CI 0.41 to 0.91),  Analysis 1.4, although the findings were heterogeneous; there were fewer operative vaginal deliveries (RR 0.89, 95% CI 0.81 to 0.98),  Analysis 1.5, and admissions to special care unit (RR 0.89, 95% CI 0.81 to 0.99),  Analysis 1.8; there was no statistically significant difference in the number of babies with low Apgar scores at five minutes or babies requiring neonatal intubation,  Analysis 1.6;  Analysis 1.7.

There was little evidence that monitoring by PR interval analysis conveyed any benefit.

 

Discussion

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms

Overall, the ST waveform trials have shown some benefits in terms of process indicators with less obstetric interference (specifically, fetal blood sampling and operative vaginal delivery) and fewer babies admitted to special care units but they have not shown substantive clinical benefits (e.g. reduced encephalopathy) among women allocated to ST waveform analysis in addition to standard cardiotocography. The ST waveform trials used different generations of the same equipment (STAN recorder, Neoventa Medical, Gothenburg, Sweden). In the UK trial (Westgate 1993), the T/QRS ratio provided the basis for identifying ST segment elevation. In the subsequent trials (Amer-Wahlin 2001; Ojala 2006; Vayssiere 2007; Westerhuis 2010), technical developments permitted the identification of ST waveform depression as well as elevation, since the former effect has also been seen in animal studies of experimentally-induced fetal hypoxaemia. Most trials were accompanied by regular education and training sessions for labour ward staff in both cardiotocogram and ECG waveform interpretation and these may be essential for optimal implementation.

 

Authors' conclusions

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms

 

Implications for practice

These findings provide some modest support for the use of fetal ST waveform analysis when a decision has been made to undertake continuous electronic fetal heart rate monitoring during labour. However, in most labours, technically satisfactory cardiotocographic traces can be obtained by external ultrasound monitors which are less invasive than internal scalp electrodes (which are required for electrocardiographic (ECG) analysis). The scalp electrode also cannot be used if the membranes are intact. One trial of fetal ECG analysis (Amer-Wahlin 2001) used guidelines for clinicians that recommended no action if cardiotocography was normal, regardless of ST waveform analyses. A better approach to incorporation into clinical practice might be to consider fetal ECG waveform analysis (of the ST waveform) only if cardiotocography showed disquieting features.

 
Implications for research

The point estimates for effects of PR analysis are similar to those from the much larger ST studies, and the possibility of demonstrating beneficial effects from a larger PR trial could not be discounted. There is little information about the value of fetal ECG waveform monitoring in preterm fetuses in labour. Information about long-term development of the babies included in the trials would be valuable.

 

Acknowledgements

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms

Thanks for additional unpublished data from Dr Jenny Westgate (Westgate 1993), Dr Christophe Vayssiere (Vayssiere 2007), and Prof Karel Marsal (Amer-Wahlin 2001).

The National Institute for Health Research (NIHR) is the largest single funder of the Cochrane Pregnancy and Childbirth Group.  The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the NIHR, NHS or the Department of Health.

 

Data and analyses

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms
Download statistical data

 
Comparison 1. Fetal ECG plus CTG versus CTG alone

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Caesarean section6Risk Ratio (M-H, Fixed, 95% CI)Subtotals only

    1.1 ST analysis
515338Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.91, 1.08]

    1.2 PR analysis
1957Risk Ratio (M-H, Fixed, 95% CI)0.79 [0.61, 1.04]

 2 Cord pH < 7.05 + base deficit > 12 mmol/L5Risk Ratio (M-H, Random, 95% CI)Subtotals only

    2.1 ST analysis
514574Risk Ratio (M-H, Random, 95% CI)0.78 [0.44, 1.37]

   2.2 PR analysis
00Risk Ratio (M-H, Random, 95% CI)0.0 [0.0, 0.0]

 3 Neonatal encephalopathy5Risk Ratio (M-H, Fixed, 95% CI)Subtotals only

    3.1 ST analysis
515302Risk Ratio (M-H, Fixed, 95% CI)0.54 [0.24, 1.25]

   3.2 PR analysis
00Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

 4 Fetal blood sampling5Risk Ratio (M-H, Random, 95% CI)Subtotals only

    4.1 ST analysis
49671Risk Ratio (M-H, Random, 95% CI)0.61 [0.41, 0.91]

    4.2 PR analysis
1957Risk Ratio (M-H, Random, 95% CI)0.91 [0.69, 1.19]

 5 Operative vaginal delivery5Risk Ratio (M-H, Fixed, 95% CI)Subtotals only

    5.1 ST analysis
49671Risk Ratio (M-H, Fixed, 95% CI)0.89 [0.81, 0.98]

    5.2 PR analysis
1957Risk Ratio (M-H, Fixed, 95% CI)0.94 [0.75, 1.17]

 6 Apgar score < 7 at 5 minutes6Risk Ratio (M-H, Fixed, 95% CI)Subtotals only

    6.1 ST analysis
515302Risk Ratio (M-H, Fixed, 95% CI)0.95 [0.73, 1.24]

    6.2 PR analysis
1957Risk Ratio (M-H, Fixed, 95% CI)0.42 [0.11, 1.62]

 7 Neonatal intubation2Risk Ratio (M-H, Fixed, 95% CI)Subtotals only

    7.1 ST analysis
11436Risk Ratio (M-H, Fixed, 95% CI)0.79 [0.29, 2.10]

    7.2 PR analysis
1957Risk Ratio (M-H, Fixed, 95% CI)0.74 [0.26, 2.11]

 8 Admission neonatal special care unit6Risk Ratio (M-H, Fixed, 95% CI)Subtotals only

    8.1 ST analysis
515302Risk Ratio (M-H, Fixed, 95% CI)0.89 [0.81, 0.99]

    8.2 PR analysis
1957Risk Ratio (M-H, Fixed, 95% CI)0.77 [0.45, 1.33]

 9 Perinatal death6Risk Ratio (M-H, Fixed, 95% CI)Subtotals only

    9.1 ST analysis
515338Risk Ratio (M-H, Fixed, 95% CI)1.49 [0.53, 4.18]

    9.2 PR analysis
1957Risk Ratio (M-H, Fixed, 95% CI)2.96 [0.12, 72.39]

10 Cerebral palsy0Risk Ratio (M-H, Fixed, 95% CI)Subtotals only

 

Appendices

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms
 

Appendix 1. Methods used to assess trials included in previous versions of this review

Reports of identified trials that appeared relevant to the objectives of the review were evaluated for inclusion. Both published and unpublished reports could be included. Attempts were made, where necessary, to translate identified, non-English language reports. Primary authors were contacted for additional details when necessary. Reasons for excluding apparently relevant trials were made explicit.

Included trials were assessed according to the following criteria:

  1. adequate concealment of treatment allocation (for example, sealed, opaque, numbered envelopes);
  2. method of allocation to treatment (for example, by computer randomisation, random number tables);
  3. adequate documentation of how exclusions were handled after treatment allocation - to facilitate 'intention-to-treat' analyses;
  4. adequate blinding of outcome assessment, where appropriate;
  5. losses to follow-up (trials with losses of more than 25% were excluded).

Data were entered directly from reports into Review Manager software (RevMan 2011) and statistical analyses performed. For dichotomous data, risk ratios and 95% confidence intervals (CIs) were calculated. Mean differences and 95% CIs were calculated for continuous data.

Heterogeneity between trials was tested using a standard chi-squared test. In the presence of significant heterogeneity, a sensitivity analysis explored the influence of high quality trials (fulfilling the criteria above) compared to those of lesser quality.

For ease of presentation, subgroup analyses were based on trials that used analysis of ST waveforms and of PR intervals.

 

What's new

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms

Last assessed as up-to-date: 12 February 2013.


DateEventDescription

12 March 2013New citation required but conclusions have not changedReview updated.

12 February 2013New search has been performedNew search. No new trials identified but citation for a secondary analysis of data from Westerhuis 2010 trial added, and ongoing trial in US noted (Spong 2013).



 

History

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms

Protocol first published: Issue 2, 1997
Review first published: Issue 2, 1997


DateEventDescription

28 February 2012New citation required but conclusions have not changedReview updated.

28 February 2012New search has been performedSearch updated. No new trials identified. References are included to published revisions of the Amer-Wahlin 2001 trial data. Economic analysis of the Westerhuis 2010 trial data cited.

19 May 2011New search has been performedSearch updated. New trial added (Westerhuis 2010). Results of existing trial (Amer-Wahlin 2001) modified, with explanation. Outcome measures refined and classed as primary and secondary. Although the results are different, the overall conclusions remain unchanged.

17 April 2009New search has been performedSearch updated and two excluded studies added (Hruban 2006; Janku 2006).

Unpublished data from the Vayssiere 2007 trial added.

10 November 2008New search has been performedThe search has been updated and an additional trial added (Vayssiere 2007).

4 November 2008AmendedIt came to our notice that one of the included trials was being investigated by the relevant university because of allegations of research misconduct. We have added text to the review to advise that the results of this review should be interpreted with great caution until the university investigation is completed and the conclusions publicised.

2 September 2008AmendedConverted to new review format.

6 April 2006New search has been performedSearch updated.

Data from a newly published trial from Finland have been included. A recent publication has discussed the identification of 'protocol violations' at interim analysis mid-way through the Swedish trial; these were used to 're-train' clinical staff in the recruiting centres.



 

Contributions of authors

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms

JP Neilson has prepared and maintained the review.

 

Declarations of interest

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms

None known.

 

Sources of support

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms
 

Internal sources

  • The University of Liverpool, UK.

 

External sources

  • No sources of support supplied

 

Differences between protocol and review

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Index terms

Methods updated.

* Indicates the major publication for the study

References

References to studies included in this review

  1. Top of page
  2. AbstractRésumé
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. What's new
  13. History
  14. Contributions of authors
  15. Declarations of interest
  16. Sources of support
  17. Differences between protocol and review
  18. Characteristics of studies
  19. References to studies included in this review
  20. References to studies excluded from this review
  21. References to ongoing studies
  22. Additional references
  23. References to other published versions of this review
Amer-Wahlin 2001 {published data only}
  • Amer-Wahlin I, Hellsten C, Noren H, Hagberg H, Herbst A, Kjellmer I, et al. Cardiotocography only versus cardiotocography plus ST analysis of fetal electrocardiogram for intrapartum fetal monitoring: a Swedish randomised controlled trial. Lancet 2001;358:534-8.
  • Amer-Wahlin I, Kallen K, Herbst A, Rydhstroem H, Sundstrom AK, Marsal K. Implementation of new medical techniques: experience from the Swedish randomized controlled trial on fetal ecg during labor. Journal of Maternal-Fetal & Neonatal Medicine 2005;18(2):93-100.
  • Amer-Wahlin I, Kjellmer I, Marsal K, Olofsson P, Rosen KG. Swedish randomized controlled trial of cardiotocography versus cardiotocography plus ST analysis of fetal electrocardiogram revisited: analysis of data according to standard versus modified intention-to-treat principle. Acta Obstetrica et Gynecologica Scandinavica 2011;90(9):990-6.
  • Amer-Wahlin I, Marsal K, Noren H, Hellsten C. Randomized controlled trial of CTG versus CTG + ST analysis of the fetal ECG. XVI FIGO World Congress of Obstetrics and Gynecology (Book 3); 2000 Sept 3-8; Washington DC, USA. 2000:35.
  • Hagberg H, Amer-Wahlin I, Hellsten C, Noren H, Herbst A, Lilja H, et al. Intrapartum fetal monitoring: cardiotocography versus cardiotocography plus fetal ECG ST waveform analysis. A Swedish randomized controlled trial. American Journal of Obstetrics and Gynecology 2001;184(1):S19.
  • Hanson J. Cardiotocography and ST analysis for intrapartum fetal monitoring. Lancet 2011;378(9797):1137-8.
  • Lund University. Decision 16 September 2010.
  • Marsal K. Personal communication 7th January 2011.
  • Marsal K. Cardiotocography and ST analysis for intrapartum fetal monitoring - author's reply. Lancet 2011;378(9797):1138.
  • Noren H, Amer-Wahlin I, Hagberg H, Herbst A, Kjellmer I, Marsal K, et al. Fetal electrocardiography in labor and neonatal outcome: data from the Swedish randomized controlled trial on intrapartum fetal monitoring. American Journal of Obstetrics and Gynecology 2003;188(1):183-92.
  • Noren H, STAN study group. Randomised controlled trial of CTG versus CTG + ST analysis of the fetal ECG. Prenatal and Neonatal Medicine 2000;5(Suppl 2):37.
  • Sundstrom AK, Swedish STAN Group. Randomised controlled trial CTG versus CTG + ST analysis of the fetal ECG. Journal of Obstetrics and Gynecology 2001;21(Suppl 1):S18-S19.
  • Swedish Research Council. Opinion provided on request for investigation of suspected misconduct in research - the STAN study. Log no 312-2008-7602.
Ojala 2006 {published data only}
Strachan 2000 {published data only}
  • Strachan BK, van Wijngaarden WJ, Sahota D, Chang A, James DK, for the FECG Study Group. Cardiotocography only versus cardiotocography plus PR-interval analysis in intrapartum surveillance: a randomised, multicentre trial. Lancet 2000;355:456-9.
  • van Wijngaarden WJ, Sahota DS, James DK, Farrell T, Mires GJ, Wilcox M, et al. Improved intrapartum surveillance with PR interval analysis of the fetal electrocardiogram: a randomised trial showing a reduction in fetal blood sampling. American Journal of Obstetrics and Gynecology 1996;174:1295-9.
  • van Wijngaarden WJ, Sahota DS, James DK, Symonds EM, Farrell T, Mires G. Does the fetal ECG improve intrapartum surveillance? II: A prospective evaluation. International Journal of Gynecology & Obstetrics 1994;46(Suppl 2):102.
Vayssiere 2007 {published data only}
  • Vayssiere C, David E, Haberstich R, Sebahoun V, Roth E, Meyer N, et al. A French randomized controlled trial on ST analysis in a population with abnormal FHR in labor. American Journal of Obstetrics and Gynecology 2006;195(6 Suppl 1):S222.
  • Vayssiere C, David E, Meyer N, Haberstich R, Sebahoun V, Roth E, et al. A French randomized controlled trial of ST-segment analysis in a population with abnormal cardiotocograms during labor. American Journal of Obstetrics and Gynecology 2007;197(3):299.e1-e6.
Westerhuis 2010 {published data only}
  • Becker J, Westerhuis M, Sterrenburg K, Kwee A, Visser G. Fetal blood sampling in the Dutch STAN-trial: reason to adjust the clinical guidelines?. American Journal of Obstetrics and Gynecology 2009;201(6 Suppl 1):S240.
  • Becker JH, Westerhuis ME, Sterrenburg K, van den Akker ES, van Beek E, Bolte AC, et al. Fetal blood sampling in addition to intrapartum ST-analysis of the fetal electrocardiogram: evaluation of the recommendations in the Dutch STAN(R) trial. BJOG: an international journal of obstetrics and gynaecology 2011;118(10):1239-46.
  • Kwee A. Cardiotocography plus ST-analysis of the fetal electrocardiogram versus cardiotocography only for intrapartum monitoring: a Dutch randomized trial. Journal of Perinatal Medicine 2009;37(Suppl 1):66.
  • Kwee A, Visser GHA. The cost-effectiveness of ST-analysis of the fetal electrocardiogram as compared to fetal blood sampling for intrapartum monitoring: a randomised controlled trial. Netherlands Trial Register (http://www.trialregister.nl) (accessed 1 November 2005).
  • Vijgen SMC, Westerhuis MEMH, Opmeer BC, Visser GHA, Moons KGM, Porath MM, et al. Cost-effectiveness of cardiotocography plus ST analysis of the fetal electrocardiogram compared with cardiotocography alone. Acta Obstetrica et Gynecologica Scandinavica 2011;90(7):772-8.
  • Westerhuis ME, Moons KG, van Beek E, Bijvoet SM, Drogtrop AP, van Geijn HP, et al. A randomised clinical trial on cardiotocography plus fetal blood sampling versus cardiotocography plus ST-analysis of the fetal electrocardiogram (STAN) for intrapartum monitoring. BMC Pregnancy and Childbirth 2007;7:13.
  • Westerhuis ME, Visser GH, Moons KG, van Beek E, Benders MJ, Bijvoet SM, et al. Cardiotocography plus ST analysis of fetal electrocardiogram compared with cardiotocography only for intrapartum monitoring: a randomized controlled trial. Obstetrics & Gynecology 2010;115(6):1173-80.
  • Westerhuis MEMH, Porath MM, Becker JH, Van Den Akker ESA, Van Beek E, Van Dessel HJHM, et al. Identification of cases with adverse neonatal outcome monitored by cardiotocography versus ST analysis: Secondary analysis of a randomized trial. Acta Obstetricia et Gynecologica Scandinavica 2012;91(7):830-7.
  • Westerhuis MEMH, Visser GHA, Moons KGM, Zuithoff NPA, Mol BWJ, Kwee A. Cardiotocography plus ST analysis of fetal electrocardiogram compared with cardiotocography only for intrapartum monitoring: a randomized controlled trial. Obstetrics & Gynecology 2011;117:406-7; 412.
Westgate 1993 {published data only}
  • Westgate J, Harris M, Curnow J, Greene K. Plymouth randomised controlled trial of 2400 cases - ST waveform plus CTG vs CTG alone for intrapartum monitoring. Proceedings of 26th British Congress of Obstetrics and Gynaecology; 1992; Manchester, UK. 1992:177.
  • Westgate J, Harris M, Curnow JSH, Greene KR. Plymouth randomized trial of cardiotocogram only vs ST waveform plus cardiotocogram for intrapartum monitoring in 2400 cases. American Journal of Obstetrics and Gynecology 1993;169:1151-60.
  • Westgate J, Harris M, Curnow JSH, Greene KR. Plymouth randomized trial of CTG vs ST waveform analysis plus CTG for intrapartum monitoring: 2400 cases. Journal of Perinatal Medicine 1992;20(1):268.
  • Westgate J, Harris M, Curnow JSH, Green KR. Randomized trial of cardiotocography alone or with ST waveform analysis for intrapartum monitoring. Lancet 1992;340:194-8.

References to studies excluded from this review

  1. Top of page
  2. AbstractRésumé
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. What's new
  13. History
  14. Contributions of authors
  15. Declarations of interest
  16. Sources of support
  17. Differences between protocol and review
  18. Characteristics of studies
  19. References to studies included in this review
  20. References to studies excluded from this review
  21. References to ongoing studies
  22. Additional references
  23. References to other published versions of this review
Hruban 2006 {published data only}
  • Hruban L, Janku P, Zahradnickova J, Kurecova B, Roztocil A, Kachlík P, et al. Role of ST-analysis of fetal ECG in intrapartal fetus monitoring with presumed growth retardation. Ceska Gynekologie 2006;71(4):268-72.
Janku 2006 {published data only}
  • Janku P, Hruban L, Kurecova B, Roztocil A, Kachlik P, Zahradnickova J. ST analysis of fetal ECG in premature deliveries during 30th-36th week of pregnancy. Ceska Gynekologie 2006;71(3):163-8.
Olofsson 2003 {published data only}
  • Olofsson P. Current status of intrapartum fetal monitoring: cardiotocography versus cardiotocography + ST analysis of the fetal ECG. European Journal of Obstetrics & Gynecology and Reproductive Biology 2003;110:S113-S118.
Prieto 2008 {published data only}
  • Prieto AP, Pareja MV, Zuniga IV, Romero TA, Leon MDR, Ventoso FM. Pulse oximetry compared with fetal electrocardiogram to control intrapartum fetal wellbeing. Journal of Maternal-Fetal and Neonatal Medicine 2008;21(Suppl 1):141.

Additional references

  1. Top of page
  2. AbstractRésumé
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. What's new
  13. History
  14. Contributions of authors
  15. Declarations of interest
  16. Sources of support
  17. Differences between protocol and review
  18. Characteristics of studies
  19. References to studies included in this review
  20. References to studies excluded from this review
  21. References to ongoing studies
  22. Additional references
  23. References to other published versions of this review
Alfirevic 2006
Amer-Wahlin 2011
  • Amer-Wahlin I, Kjellmer I, Marsal K, Olofsson P, Rosen KG. Swedish randomized controlled trial of cardiotocography only versus cardiotocography plus ST analysis of fetal electrocardiogram revisited: Analysis of data according to standard versus modified intention-to-treat principle. Acta Obstetrica et Gynecologica Scandinavica 2011;90(9):990-6.
Dawes 1994
Elbourne 2002
Greene 1987
  • Greene KG. The ECG waveform. In: Whittle M editor(s). Baillieres Clinical Obstetrics and Gynaecology. Vol. 1, London: Bailliere Tindall, 1987:131-55.
Greene 1999
  • Greene K. Intrapartum fetal monitoring: CTG, ECG and fetal blood sampling. In: Rodeck CH, Whittle MJ editor(s). Fetal Medicine: Basic Science and Clinical Practice. London: Churchill Livingstone, 1999:985-1004.
Higgins 2011
  • Higgins JPT, Green S, editors. Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.
Marsal 2011
  • Marsal K. Cardiotocography and ST analysis for intrapartum fetal monitoring - author's reply. Lancet 2011;378(9797):1138.
RevMan 2011
  • The Nordic Cochrane Centre, The Cochrane Collaboration. Review Manager (RevMan). 5.1. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2011.
Rosen 1989
  • Rosen KG, Lindecrantz K. STAN - the Gothenburg model for fetal surveillance during labour by ST analysis of the fetal ECG. Clinical Physics and Physiological Measurement 1989;10(Suppl B):51-6.
Rosen 1991
  • Rosen KG, Arulkumaran S, Greene KR, Lilja H, Lindecrantz K, Seneviratne H, et al. Clinical validity of fetal ECG waveform analysis. In: Saling E editor(s). Perinatology. Nutrition Workshop Series. Vol. 26, New York: Raven Press, 1991:95-110.
Swedish Research Council 2010
  • Swedish Research Council. Opinion provided on request for investigation of suspected misconduct in research - the STAN study. Log no 312-2008-7602.

References to other published versions of this review

  1. Top of page
  2. AbstractRésumé
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. What's new
  13. History
  14. Contributions of authors
  15. Declarations of interest
  16. Sources of support
  17. Differences between protocol and review
  18. Characteristics of studies
  19. References to studies included in this review
  20. References to studies excluded from this review
  21. References to ongoing studies
  22. Additional references
  23. References to other published versions of this review
Neilson 1995
  • Neilson JP. Intrapartum fetal ECG plus heart rate recording. [revised 12 May 1994]. In: Enkin MW, Keirse MJNC, Renfrew MJ, Neilson JP, Crowther C (eds) Pregnancy and Childbirth Database [database on disk and CDROM]. The Cochrane Collaboration; Issue 2, Oxford: Update Software; 1995.
Neilson 2003
  • Neilson JP Reviews. Fetal electrocardiogram (ECG) for fetal monitoring during labour. Cochrane Database of Systematic Reviews 2003, Issue 2. [DOI: 10.1002/14651858.CD000116]
Neilson 2006
Neilson 2012