Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour
Editorial Group: Cochrane Pregnancy and Childbirth Group
Published Online: 8 OCT 2008
Assessed as up-to-date: 23 APR 2006
Copyright © 2008 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
How to Cite
Alfirevic Z, Devane D, Gyte GML. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database of Systematic Reviews 2006, Issue 3. Art. No.: CD006066. DOI: 10.1002/14651858.CD006066.
- Publication Status: Edited (no change to conclusions)
- Published Online: 8 OCT 2008
Cardiotocography (sometimes known as electronic fetal monitoring), 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), so additional assessments of fetal well-being may be used, or the baby delivered by caesarean section or instrumental vaginal birth.
To evaluate the effectiveness of continuous cardiotocography during labour.
We searched the Cochrane Pregnancy and Childbirth Group Trials Register (March 2006), CENTRAL (The Cochrane Library 2005, Issue 4), MEDLINE (1966 to December 2005), EMBASE (1974 to December 2005), Dissertation Abstracts (1980 to December 2005) and the National Research Register (December 2005).
Randomised and quasi-randomised controlled trials involving a comparison of continuous cardiotocography (with and without fetal blood sampling) with (a) no fetal monitoring, (b) intermittent auscultation (c) intermittent cardiotocography.
Data collection and analysis
Two authors independently assessed eligibility, quality and extracted data.
Twelve trials were included (over 37,000 women); only two were high quality. Compared to intermittent auscultation, continuous cardiotocography showed no significant difference in overall perinatal death rate (relative risk (RR) 0.85, 95% confidence interval (CI) 0.59 to 1.23, n = 33,513, 11 trials), but was associated with a halving of neonatal seizures (RR 0.50, 95% CI 0.31 to 0.80, n = 32,386, nine trials) although no significant difference was detected in cerebral palsy (RR 1.74, 95% CI 0.97 to 3.11, n = 13,252, two trials). There was a significant increase in caesarean sections associated with continuous cardiotocography (RR 1.66, 95% CI 1.30 to 2.13, n =18,761, 10 trials). Women were also more likely to have an instrumental vaginal birth (RR 1.16, 95% CI 1.01 to 1.32, n = 18,151, nine trials). Data for subgroups of low-risk, high-risk, preterm pregnancies and high quality trials were consistent with overall results. Access to fetal blood sampling did not appear to influence the difference in neonatal seizures nor any other prespecified outcome.
Continuous cardiotocography during labour is associated with a reduction in neonatal seizures, but no significant differences in cerebral palsy, infant mortality or other standard measures of neonatal well-being. However, continuous cardiotocography was associated with an increase in caesarean sections and instrumental vaginal births. The real challenge is how best to convey this uncertainty to women to enable them to make an informed choice without compromising the normality of labour.
Plain language summary
Comparing continuous electronic monitoring of the baby's heartbeat in labour using cardiotocography (CTG, sometimes known as EFM) with intermittent monitoring (intermittent auscultation, IA)
Monitoring the baby's heartbeat is one way of checking babies' well-being in labour. By listening to, or recording the baby's heartbeat, it is hoped to identify babies who are becoming short of oxygen (hypoxic) and who may benefit from caesarean section or instrumental vaginal birth. A baby's heartbeat can be monitored intermittently by using a fetal stethoscope, Pinard (special trumpet shaped device), or by a handheld Doppler device. The heartbeat can also be checked continuously by using a CTG machine. This method is sometimes known as electronic fetal monitoring (EFM) and produces a paper recording of the baby's heart rate and their mother's labour contractions. Whilst a continuous CTG gives a written record, it prevents women from moving during labour. This means that women may be unable to change positions or use a bath to help with comfort and control during labour. It also means that some resources tend to be focused on the needs of the CTG rather than the woman in labour. This review compared continuous CTG monitoring with intermittent auscultation (listening). It found 12 trials involving over 37,000 women. Most studies were not of high quality and the review is dominated by one large, well-conducted trial of almost 13,000 women who received care from one person throughout labour in a hospital where the membranes have either ruptured spontaneously or were artificial ruptured as early as possible and oxytocin stimulation of contractions was used in about a quarter of the women. There was no difference in the number of babies who died during or shortly after labour (about 1 in 300). Fits (neonatal seizures) in babies were rare (about 1 in 500 births), but they occurred significantly less often when continuous CTG was used to monitor fetal heart rate. There was no difference in the incidence of cerebral palsy, although other possible long-term effects have not been fully assessed and need further study. Continuous monitoring was associated with a significant increase in caesarean section and instrumental vaginal births. Both procedures are known to carry the risks associated with a surgical procedure although the specific adverse outcomes have not been assessed in the included studies.