In July 1985, exactly 40 years ago, the Dublin randomised controlled trial of fetal monitoring in labour was published. This was meant to be the trial that was finally going to provide a definitive answer to the question of whether CTG monitoring was better for babies than using intermittent auscultation (which had been the established norm before CTGs arrived). Prior to July 1985 there had been five randomised controlled trials published (and another was underway) comparing CTG use with intermittent auscultation. None enrolled more than 1,ooo women, meaning they lacked the statistical oomph required to show meaningful differences in outcomes for babies, and none had shown any signs that CTG monitoring was better than intermittent auscultation for babies.
The Dublin trial was designed to be the one that would finally “help resolve the controversy about the place of more intensive methods of intrapartum fetal monitoring” (MacDonald et al., 1985, p. 525). I often hear people misrepresenting what the trial found, so on this 40 year anniversary, it seems a good time to take a deeper look at how it was done and what was found.
What they did
The research team set out to enrol 10,000 women, having calculated that that would be enough to show a 50% reduction (if one existed) in a combined outcome of stillbirth during labour, neonatal death, neonatal seizures, and other severe neurological problems. When they got close to this, they decided to push on, in the hope that adding 3,000 more women would mean they could independently see if death rates were different, or if seizure rates were different.
All women who were in labour at the National Maternity Hospital in Dublin between March 1981 and April 1983 were entered into the trial – with the only exceptions being women who had a caesarean section before labour, fetal death before labour, who gave birth so quickly there was no time to think about the trial, or were under 28 weeks of gestation or the baby was known to have a serious abnormality, with the final exclusion criterion being the absence of amniotic fluid after rupturing the membranes (this was done routinely at the hospital at the time) or heavily meconium stained amniotic fluid. Women were then randomly assigned to either CTG monitoring (with a fetal scalp electrode and an external tocodynanometer) or intermittent auscultation (with a Pinard, only using a Doppler when there was difficulty with hearing the heart sounds this way).
Only the women allocated to CTG monitoring were told that they were part of a trial and their consent was sought, with 331 refusing CTG use. Women allocated to intermittent auscultation were not told they were part of a trial and were not given any choice of fetal monitoring method. (Ethics, sigh.) In total, 12,964 women were enrolled (6,474 allocated to CTG use and 6,490 to intermittent auscultation), and they gave birth to 13,084 babies (because women with multiple pregnancies were included). Virtually all (97.7%) of women allocated to intermittent auscultation were monitored this way, and 80.7% of women allocated to CTG use were monitored by CTG. The analysis was done based on the groups women were allocated to, rather than what was actually done.
What they found
There’s a HUGE amount of detail in the published paper, and I would reproduce all of it here. The key outcomes for babies were:
- Stillbirth during labour – there were three in each group, so no significant difference.
- Neonatal death – there were eleven deaths in the CTG monitoring arm of the trial, twelve in the intermittent auscultation arm, so no significant difference.
- Neonatal seizures – there were twelve babies with seizures in the CTG monitoring arm of the trial and 27 in the intermittent auscultation arm of the trial. The difference here was significant.
- Other neurological problems – these were only reported for the first 10,094 babies in the trial, with 16 affected in the CTG arm and 25 in the intermittent auscultation arm. The difference was not significant.
- At one year of age three babies in each group had been diagnosed with cerebral palsy, so no significant difference.
- When they followed the babies up to age 4 (Grant et al., 1989) there were 12 babies with cerebral palsy in the CTG monitoring arm and 10 in the intermittent auscultation arm of the trial, so also no significant difference.
They also found no difference in the rates of low Apgars at five minutes of age, the use of intubation for resuscitation, admission to the nursery, or umbilical cord venous pH.
What the authors don’t write about in the body of the paper, but you can figure out from looking at the numbers in the tables and doing some maths, is that the rate of seizures was identical between the two groups when their mothers were not given an oxytocin infusion during their labour. The rate of seizures was much higher when oxytocin was given, and was significantly less among women allocated to CTG monitoring than it was for women allocated to intermittent auscultation.
For the women the key outcomes were:
- Caesarean section for any reason – 2.4% of women in the CTG monitoring arm and 2.2% in the intermittent auscultation arm, not significantly different.
- Caesarean section for “fetal distress” – 0.4% of women in the CTG monitoring arm and 0.2% in the intermittent auscultation arm, a significant difference.
- Forceps birth for any reason (note that vacuum extraction was not used at this hospital) – 8.2% of women in the CTG monitoring arm and 6.3% in the intermittent auscultation arm, significantly different – with most of this difference due to forceps being used when there was “fetal distress”.
What people often get wrong about this trial
In summary then, this trial showed that CTG use didn’t save baby’s lives, and didn’t prevent long term brain injury, any better than could be achieved with intermittent auscultation. More women had caesarean sections and forceps births for abnormal heart rate patterns when CTGs were used than when intermittent auscultation was used – so by definition these extra surgical births were unnecessary (as they clearly didn’t result in better outcomes for the babies). Seizures were lower when CTG monitoring was used for women on an oxytocin infusion, but 1. this didn’t translate through into any long term differences in brain injury and 2. the findings may or may not relate to today’s practice given that the way oxytocin is delivered is now quite different.
So the trial is NOT compelling evidence that CTG monitoring is fabulous and should be used widely. Yet I often read or hear of this trial being put forward as proof that do CTGs work. The other common myth I hear is that the Dublin trial only included “low risk” women, and anyone saying that clearly hasn’t actually read the thing!
The authors of the trial appeared to be a bit put out that the results went the way they did. They focussed very strongly on the difference in seizure rates in the discussion section of the paper, writing that:
The implications of our findings for obstetric practice must necessarily depend on judgements concerning the significance of preventing intrapartum fetal asphyxia and thereby reducing abnormal neurological signs during the neonatal period. These abnormalities are often disturbing for parents and staff alike. Whatever their longer term implications may turn out to be, some people will undoubtedly feel it is important to prevent them by more intensive intrapartum fetal monitoring in all labours.
p. 538
When the longer term implications were reported (Grant et al., 1989), rather than concluding that CTG use had now been found to be ineffective and should be abandoned, the National Maternity Hospital continued using CTGs. The closing argument in this second paper distracted readers from considering the possibility of a return to intermittent auscultation as the standard of care, instead concluding that:
Obstetric practice is beset by worries about medical negligence. Our results indicate that preventable intrapartum asphyxia is a much less common cause of cerebral palsy than is often expected.
p 1235
This simply feeds into the ongoing and ever present fear of litigation that is known to drive CTG use.
It’s well beyond time to let go of the obsession with CTG use
By July 1985 the obstetric world had the results of the “definitive” CTG trial – and it showed that CTGs didn’t save lives or prevent long term brain injury, but that women had more surgical births. Another six randomised controlled trials were conducted between this time and 2006 when the most recent one was published. None of them alter this conclusion (though the large trial by Leveno et al., 1986 showed no difference in neonatal seizures). You would think that at some point in the past 40 years, practice would slowly have aligned with the evidence. But clearly that hasn’t happened.
I’m tired of waiting for someone else to come along and fix it – so I’ve been doing whatever I can to try to turn the tide. If you are a maternity professional and you want to dust off your intermittent auscultation skills and knowledge and put them to better use – let me help you with that!
Are you ready to tackle your lack of confidence with intermittent auscultation?
It’s time to fix the inappropriate over use of CTG monitoring and shift practice in a direction that aligns with evidence. If you are a maternity professional and the thought of offering intermittent auscultation to more women (including some considered “high-risk”) gives you a tight uncomfortable feeling in your chest – let me fix that for you.
On Saturday August 2nd, 2025 at 2 pm AEST (Brisbane time – that’s GMT+10) I’ll be hosting a LIVE online 2 hour long workshop, called Confident Intermittent Auscultation. Join me and address each of the fear points that is holding you back. I’ll take you through the evidence and provide my eight top tips for how to do intermittent auscultation in a way that keeps you, the woman, and her baby safe.
Register by clicking the link below for more information about the workshop
Want to know more?
References
Grant, A., O’Brien, N., Joy, M. T., Hennessy, E., & MacDonald, D. (1989, Nov). Cerebral palsy among children born during the Dublin randomised trial of intrapartum monitoring. Lancet, 2(8674), 1233-1236. https://doi.org/10.1016/s0140-6736(89)91848-5
Leveno, K. J., Cunningham, F. G., Nelson, S. M., Roark, M., Williams, M. L., Guzick, D., Dowling, S., Rosenfeld, C. R., & Buckley, A. (1986, Sep 04). A prospective comparison of selective and universal electronic fetal monitoring in 34,995 pregnancies. New England Journal of Medicine, 315(10), 615-619. https://doi.org/10.1056/NEJM198609043151004
MacDonald, D., Grant, A., Sheridan-Pereira, M., Boylan, P. C., & Chalmers, I. (1985, Jul). The Dublin randomized controlled trial of intrapartum fetal heart rate monitoring. American Journal of Obstetrics & Gynecology, 152(5), 524-539. https://doi.org/0002-9378
Categories: CTG, EFM, History, Perinatal brain injury, Perinatal mortality, Reflections
Tags: Cerebral palsy, Dublin, seizures
Birth Small Talk 
Hello 🙂
Where can I find the other 6 RCTs (including the 2006 one) that were publishes subsequently to the Dublin Trial?
Thank you!
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If you look at the list given in the Cochrane review by Alfirevic et al., 2017, you’ll find all 11 of the randomised controlled trials there.
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