Computerised interpretation of the fetal heart rate during labour: a randomised controlled trial (INFANT)

Abstract

BackgroundContinuous electronic fetal monitoring (EFM) in labour is widely used and computerised interpretation has the potential to increase its utility.ObjectivesThis trial aimed to find out whether or not the addition of decision support software to assist in the interpretation of the cardiotocograph (CTG) reduced the number of poor neonatal outcomes, and whether or not it was cost-effective.DesignTwo-arm individually randomised controlled trial. The allocations were computer generated using stratified block randomisation employing variable block sizes. The trial was not masked.SettingLabour wards in England, Scotland and the Republic of Ireland.ParticipantsWomen in labour having EFM, with a singleton or twin pregnancy, at ≥ 35 weeks’ gestation.InterventionsDecision support or no decision support.Main outcome measuresThe primary outcomes were (1) a composite of poor neonatal outcome {intrapartum stillbirth or early neonatal death (excluding lethal congenital anomalies), or neonatal morbidity [defined as neonatal encephalopathy (NNE)], or admission to a neonatal unit within 48 hours for ≥ 48 hours (with evidence of feeding difficulties, respiratory illness or NNE when there was evidence of compromise at birth)}; and (2) developmental assessment at the age of 2 years in a subset of surviving children.ResultsBetween 6 January 2010 and 31 August 2013, 47,062 women were randomised and 46,042 were included in the primary analysis (22,987 in the decision support group and 23,055 in the no decision support group). The short-term primary outcome event rate was higher than anticipated. There was no evidence of a difference in the incidence of poor neonatal outcome between the groups: 0.7% (n = 172) of babies in the decision support group compared with 0.7% (n = 171) of babies in the no decision support group [adjusted risk ratio 1.01, 95% confidence interval (CI) 0.82 to 1.25]. There was no evidence of a difference in the long-term primary outcome of the Parent Report of Children’s Abilities-Revised with a mean score of 98.0 points [standard deviation (SD) 33.8 points] in the decision support group and 97.2 points (SD 33.4 points) in the no decision support group (mean difference 0.63 points, 95% CI –0.98 to 2.25 points). No evidence of a difference was found for health resource use and total costs. There was evidence that decision support did change practice (with increased fetal blood sampling and a lower rate of repeated alerts).LimitationsStaff in the control group may learn from exposure to the decision support arm of the trial, resulting in improved outcomes in the control arm. This was identified in the planning stage and felt to be unlikely to have a significant effect on the results. As this was a pragmatic trial, the response to CTG alerts was left to the attending clinicians.ConclusionsThis trial does not support the hypothesis that the use of computerised interpretation of the CTG in women who have EFM in labour improves the clinical outcomes for mothers or babies.Future workThere continues to be an urgent need to improve knowledge and training about the appropriate response to CTG abnormalities, including timely intervention.Trial registrationCurrent Controlled Trials ISRCTN98680152.FundingThis project was funded by the National Institute for Health Research (NIHR) HTA programme and will be published in full inHealth Technology Assessment; Vol. 22, No. 9. See the NIHR Journals Library website for further project information. Sara Kenyon was part funded by the NIHR Collaboration for Leadership in Applied Health Research and Care West Midlands.

Recruitment, consent and retention of participants in randomised controlled trials: a review of trials published in the National Institute for Health Research (NIHR) Journals Library (1997–2020)

“…The RCT with the highest final recruitment target and highest number recruited was an obstetrics trial investigating computerised interpretation of fetal heart rate during labour. 24 There were four trials that recruited less than 10 participants, two were discontinued at the end of an internal pilot phase due to low recruitment 25 26 and the remaining two had no pilot phase. 27 28 Overall, 63% (245/388) of trials recruited to their final recruitment target but 32% (79/245) of these trials required an extension to their recruitment period to meet the target.…”

“…The final recruitment target (sample size) ranged from 44 participants to 46 000 participants and the final number recruited ranged from 2 participants to 47 062. The RCT with the highest final recruitment target and highest number recruited was an obstetrics trial investigating computerised interpretation of fetal heart rate during labour 24. There were four trials that recruited less than 10 participants, two were discontinued at the end of an internal pilot phase due to low recruitment25 26 and the remaining two had no pilot phase 27 28.…”

“…The highest median recruitment rate was for dentistry (1.95 participants recruited per centre per month) but this was only from five trials. The largest recruitment rates were found to be from four obstetrics and gynaecology trials,24 29 33 34 a mental health trial35 and three trials from other clinical areas 36–38…”

“…The RCT with the highest final recruitment target and highest number recruited was an obstetrics trial investigating computerised interpretation of fetal heart rate during labour. 24 There were four trials that recruited less than 10 participants, two were discontinued at the end of an internal pilot phase due to low recruitment 25 26 and the remaining two had no pilot…”

Evaluation of 3-tier and 5-tier FHR pattern classifications using umbilical blood pH and base excess at delivery

“…In cardiotocography (CTG), fetal conditions are monitored by continuous measurement of fetal heart rate (FHR) and uterine contractions. This monitoring provides nearly real-time fetal well-being from heart rate changes and is used in 89% of delivery cases in the United States (2004) [1], 91% in Canada (2009) [2], approximately 60% in the United Kingdom (UK) as National Institute for Health and Care Excellence (NICE) guidelines for fetal monitoring in the NHS detail explicit criteria for this monitoring (2018) [3]. In Japan, it is estimated to be almost 100%.…”