Myth busting #1: There is no alternative to the CTG

From time to time, I read a paper and encounter something about fetal heart rate monitoring that makes my eyes roll. Over the next few weeks I’m going to share some of these with you, and explain what the writers got wrong, why, and what I wish they would write instead. I’m not going to provide you with details about the source of these quotes – other than to say they come from recently published peer-reviewed literature. I’m not setting out to shame the authors – but to make an educational point. These sorts of statements pop up repeatedly – so this isn’t about any particular person’s use of the particular string of words.

Join me on this myth busting adventure!

This is the piece of text that started me thinking I really need to explain what is wrong here:

Currently, medical practitioners primarily rely on cardiotocography (CTG), a tool that monitors uterine contractions and fetal heartbeat, to make risk assessments and decide whether interventions are recommended for the safety of the labouring person and / or baby (e.g. caesarean section, inducing labour, assistive tools). CTG as an evaluation tool has significant limitations, but no better tools exist for continuous fetal monitoring in labour.

Before you read on – take a moment to reflect on this, and see if you can spot anything that might not be quite right about it. I can find four. Can you see any? Maybe you’ll notice something I haven’t – if that is the case, drop it in the comments box!

Myth 1: The CTG is a tool that monitors

The CTG machine generates a graph, showing the fetal heart rate and the activity of the woman’s uterus. This is literally where the name cardio- (heart), toco- (uterine contractions), -graph comes from. But CTG machines don’t DO monitoring. Humans do.

The term monitoring means to judge the quality of something. I define CTG monitoring as the interpretation of the fetal heart rate and maternal uterine activity patterns over time in order to determine the quality of the recording and the clinical significance of the patterns. Monitoring only occurs when a person has the knowledge required to interpret the CTG, the authority to act on their interpretation, and the knowledge and skill required to perform appropriate interventions in response to their interpretation.

If a woman is attached to CTG equipment and a CTG recording is being generated – but no one looks at it, is there any monitoring going on? Well that would clearly be a great big no. So CTGs are not a tool that monitors anything. They generate a recording, that can be interpreted by a person with the required knowledge, skill, and authority, in order to achieve monitoring.

What would I have written here? “CTG is a tool that generates a recording of the fetal heart rate and uterine contractions. Maternity professionals can interpret the recording, and use this to inform decisions about when to recommend other interventions.”

Myth 2: The CTG is a tool to improve the safety of women in labour

CTGs cannot, and never will, improve health outcomes for women. It is not what they were designed to do. In theory, the only outcome for women that might be avoided by CTG use is the emotional distress associated with having an undesired outcome for their baby. There is, of course, no robust evidence that CTG use prevents deaths or long term brain injury, so the point remains theoretical.

The very best that can be hoped for with CTG use is to have no impact on a woman’s health outcomes. The evidence is clear that CTG use increases the use of caesarean section and instrumental birth, and decreases non-instrumental vaginal birth. Depending on how you think of these ways of giving birth, caesarean section and instrumental birth can be considered a form of harm. If the woman didn’t want these to happen, and they were done because of the interpretation of the CTG, and never had the potential to improve outcomes for the baby, then this in an unintended consequence of CTG use. The additional pain, higher rates of heavy bleeding and blood transfusion, blood clots, wound infections, and the longer term consequences of caesarean section are all harms arising from CTG use.

What would I have written here? I would remove mention of the woman (or labouring person to use the language of the original authors) from the sentence. Because I’m fussy about these things, I would also change baby to fetus. The final part of the sentence would read “… for fetal safety.”

Myth 3: The CTG achieves continuous fetal monitoring in labour

At best, the CTG achieves a continuous recording of the fetal heart rate in labour. Of course – it can only ever capture the part of the labour that occurs in a facility where CTGs are available, not what happens before then. And most CTG recordings have short periods where the fetal heart rate is not being recorded, either at all, or because the woman’s heart rate is being recorded instead, or the computer inside the CTG machine is generating nonsense while it tries to guess what the heart rate is. This is usually called loss of contact. It happens more often with an external Doppler sensor than with a fetal spiral electrode, or the new externally worn fetal ECG sensors. But even with these, not every single beat is always reliably recorded.

Even if an entirely continuous CTG recording were able to be achieved, the monitoring part of this equation will always remain intermittent. It simply impossible for a maternity professional to sit and look at the CTG continuously and interpret it. Guideline writers have increasingly recognised this in recent years, and most now require that a formal process of risk assessment, CTG interpretation, care planning, communication, and documentation occur at set intervals. Here in Australia, the RANZCOG guidelines (2019) require that “the trace should be reviewed at least every 15-30 minutes”. This is the same frequency as the recommendation for when intermittent auscultation should be done. The difference in how often the monitoring is happening with each of the two options is far less than people imagine it to be.

While the person in the room might glance at, or hear the sounds from, the CTG more often than every 15-30 minutes, if they aren’t actually focussing on them, then this isn’t monitoring. If they are busy engaged in another task, and therefore can’t act on their interpretation of CTG recording, then this isn’t monitoring. If there is a person sitting in front of a bank of screens at the central monitoring station, then they might be continuously looking at the screens, but only at one CTG at a time. And if they make a phone call or walk up to a room to raise their concerns about the CTG, then they can’t still be looking at the monitors continuously. There really is no such thing as continuous fetal heart rate monitoring.

What would I write instead? I would either drop the word continuous from the front of CTG monitoring, or I would call it continuous CTG recording (while recognising that even that is not technically possible).

Myth 4: There is no better tool for fetal monitoring in labour

The phrase “no better tools exist for continuous fetal monitoring in labour” has two issues and I have covered the continuous bit above. It is strictly speaking true that there are no tools (including the CTG) that achieve continuous fetal monitoring. If we rephrase and say “no better tools exist for fetal monitoring in labour”, then this statement writes both intermittent auscultation, and the work that the midwife (or nurse or other person attending the woman in labour) is doing, out of existence. And that’s not ok.

First, intermittent auscultation is a realistic choice of fetal monitoring method in most situations. (I can only come up with one and a half reasons to recommend CTGs instead). The evidence base confirms that intermittent auscultation is not worse for the fetus / baby in almost all situations, and might, maybe, be the safer option in preterm labour. (Based on some really old and possibly no longer relevant research.) Intermittent auscultation avoids the higher rate of unnecessary interventions for women seen with CTG use, and I would argue this makes it the better tool for fetal monitoring in labour.

The other thing that becomes invisible with this statement is the work the person attending the birth is doing – though I certainly wouldn’t call them a tool! Hands down, the most effective form of fetal monitoring is to have a knowledgeable and experienced care provider, who is present all the time (allowing for toilet breaks), and who has timely access to any interventions that might become appropriate at some point. There’s plenty of research showing the HUGE impact that midwives have on outcomes for babies, and as a bonus, they also dramatically improve outcomes for women (WHO, 2024). Midwives bring all their senses to the work they do, and really are continuously monitoring the big picture, even if they can’t possibly notice all the things all at the same time.

What would I have written here? “CTG as an evaluation tool has significant limitations, and has not been proven to be better than the use of intermittent auscultation.”

My request of you

No matter who you are and whether you are writing or speaking, please think about the language you are using when you talk about fetal heart rate monitoring. Make sure you aren’t perpetuating the same myths that I have drawn attention to today. Intermittent auscultation exists and is a good option, midwives (and others) do monitoring – not machines, and fetal heart rate monitoring is always intermittent. CTGs can never benefit women, but can harm them.

Join me again next week as I bust some more myths. Have you seen any in peer-reviewed literature or guidelines that you would love me to blog about? Get in touch!

Sign Up for the BirthSmallTalk Newsletter and Stay Informed!

Want to stay up-to-date with the latest research and course offers? The monthly newsletter is here to keep you in the loop.

By subscribing to the newsletter, you’ll gain exclusive access to:

Exciting Announcements: Be the first to know about upcoming courses. Stay ahead of the curve and grab your spot before anyone else!
Exclusive Offers and Discounts: As a valued subscriber, you’ll receive special discounts and offers on courses. Don’t miss the chance to save money while investing in your knowledge development.

Join the growing community of BirthSmallTalk folks by signing up for the newsletter today!

Sign up to the Newsletter

Join Now

References

Royal Australian and New Zealand College of Obstetricians and Gynaecologists. (2019). Intrapartum fetal surveillance clinical guideline. 4th Edn. https://ranzcog.edu.au/statements-guidelines

Work Health Organization. (2024). Transitioning to midwifery models of care: global position paper. https://www.who.int/publications/i/item/9789240098268