With acknowledgement to Dr Nadine Edwards and Dr Gosia Stach for introducing me to this particular logical fallacy.
The existence of any particular technology and the knowledge and processes related to it are typically considered to possess a self-evident truth. If the technology exists, then it does so because it must work. Otherwise, why would it exist and why would we be using it? There is a circular argument which sits at the heart of the beliefs about fetal monitoring technology and it consists of three logic steps.
The bad thing didn’t happen – so it works!
The first step states that if the technology is used and the anticipated the thing the technology was used to prevent doesn’t happen, then that is proof the technology works. The number of women who experience either severe brain injury or the death of their baby is very small. So at least 99% of the time that CTG monitoring is used, The Bad Thing doesn’t happen, making it easy to think that it must be due to the CTG monitoring. If you can get even more women to use CTG monitoring by including women with a lower chance of having a bad thing happen, then it the number who have The Bad Thing happen is even lower. It really is a self-fulfilling prophecy!
The bad thing happened – but it was someone’s fault
You might then think that if The Bad Thing does occur, people would start to question whether the technology worked. That’s actually not what happens. This next step makes sure the belief in the technology is still strong (and possibly made stronger) when The Bad Thing still happens. How does that work?
The second step works like this: if the CTG was used and The Bad Thing happens, then there will be a search for the individual responsible for this outcome. The two most likely people to be held responsible for this are the woman herself and the woman’s midwife. Sometimes, but less often, an obstetrician might be held to account. If an investigation identifies someone who can be blamed, then this serves as proof that the CTG still works – it was the person’s fault.
The woman might be blamed for not arriving at the hospital soon enough, or being too big for the technology to work correctly, or for moving too much, or for taking the CTG off at the wrong time, or so on. The maternity professional might be blamed for not getting the woman to use the CTG at the “right” time, or for not interpreting the heart rate the “right” way, or getting another health professional to take the “right” action at the “right time”.
This existence of this step works really well for a lot of people. It generates a market for professional education, and the organisations who provide the education get a free pass to credibility and big money. It also drives the development and use of more technology – like central fetal monitoring systems that mean people can keep an eye on what other people are up to. Ironically, this step works best when there is a small but steady trickle of poor outcomes. This supports the argument that people continue to be the reason the technology doesn’t work and so you need even more of this thing (that I want to sell you). If CTG monitoring actually worked, then there would be little need for education courses, computerised systems, and central monitoring.
It was never meant to fix that
The third step says that if the technology was used and The Bad Thing happened, but you can’t find someone to blame, then this particular bad thing was simply unavoidable and could never have been prevented by the technology in the first place! The belief the technology works is take to be true, but just not in this isolated case.
When CTGs were first introduced, almost all cases of cerebral palsy were said to be due to low oxygen levels in labour – something that CTGs were meant to be able to fix. Research done in the late 1980s showed that CTGs didn’t reduce cerebral palsy rates (Grant et al., 1989; Shy et al., 1990). Not long after, researchers started to say that only SOME babies with brain injury get it because of low oxygen levels in labour (Nelson & Leviton, 1991; Stanley & Blair, 1991). Recent research shows that even when people think that low oxygen levels in labour were to blame for the child’s cerebral palsy, many have a genetic cause (Wang et al., 2024).
Cerebral palsy is uncommon and if low oxygen levels are an uncommon cause for cerebral palsy (Philpott et al., 2020), that means that the possibility that CTG monitoring might be able to prevent cerebral palsy is vanishingly small. Rather than proving that CTGs don’t work the way people think they do – this final step ironically continues to reinforce the belief that CTG monitoring does work (but just not for this one person).
How do we break out of this cycle?
Good research gives us the tools to see whether a birth technology like CTG monitoring actually works or not. CTG use has been under-investigated. This means that many promoters of CTGs argue that if the right research was done then we would finally prove what they knew all along. I think it is time the promoters of CTG technology are asked to fund and conduct the research we need to settle this once and for all. If they aren’t willing to do that, they should be told to stop selling false promises to people and withdraw their products from clinical use.
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References
Grant, A., Joy, M.-T., O’Brien, N., Hennessy, E., & MacDonald, D. (1989). Cerebral palsy among children born during the Dublin trial randomised trial of intrapartum monitoring. Lancet, 334(8674), 1233-1236. https://doi.org/10.1016/s0140-6736(89)91848-5
Nelson, K. B., & Leviton, A. (1991, Nov). How much of neonatal encephalopathy is due to birth asphyxia? American Journal of Diseases of Children (1960), 145(11), 1325-1331. DOI: 10.1001/archpedi.1991.02160110117034
Philpot, P., Greenspan, J., & Aghai, Z. H. (2020). Problems During Delivery as an Etiology of Cerebral Palsy in Full-Term Infants. In Cerebral Palsy (pp. 67-76). https://doi.org/10.1007/978-3-319-74558-9_6
Shy, K. K., Luthy, D. A., Bennett, F. C., Whitfield, M., Larson, E. B., van Belle, G., Hughes, J. P., Wilson, J. A., & Stenchever, M. A. (1990, Mar 01). Effects of electronic fetal-heart-rate monitoring, as compared with periodic auscultation, on the neurologic development of premature infants. New England Journal of Medicine, 322(9), 588-593. https://doi.org/10.1056/NEJM199003013220904
Stanley, F. J., & Blair, E. (1991, May 06). Why have we failed to reduce the frequency of cerebral palsy? The Medical Journal of Australia, 154(9), 623-626. https://doi.org/10.5694/j.1326-5377.1991.tb121226.x
Wang, Y., Xu, Y., Zhou, C., Cheng, Y., Qiao, N., Shang, Q., Xia, L., et al. (2024, May). Exome sequencing reveals genetic heterogeneity and clinically actionable findings in children with cerebral palsy. Nature Medicine, 30(5), 1395-1405. https://doi.org/10.1038/s41591-024-02912-z
Categories: CTG, EFM, Obstetrics, Perinatal brain injury, Perinatal mortality, Reflections
Tags: Capitalism, Logical fallacy, technology
Birth Small Talk 
This is important. I can’t count the number of articles I have read over recent years where a new system of computer analysis has been applied to CTGs. On each occasion there was no difference in outcome but the conclusion was always that we need more sophisticated computer analysis of CTGs!
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I call it the “if we just tried harder” discourse. It seemed to start right about the same time that the first RCT was published showing no benefit. It is really difficult to shift!
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Probably my favourite line
“Research permits us to see whether a birth technology actually improves outcomes, or alternately whether it generates new problems”.
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It’s not even accurate technology, it merely plots change of shape of the maternal abdomen, which approximates to contractions (not strength) and an ultrasound approximation to FHR. So much more information is lost by people not looking at/listening to/watching over the woman (instead of the machine). But hey, the machine record of FHR has to be more scientific than a midwife writing down (or plotting) FHR. But worst of all it constricts women’s instinctive movement and constrains them in one position. Theoretically, the straps themselves might even restrict fetal movement which may be responsible for the locus of the contraction (see my WordPress post on Kick Starting Labour). But the lawyers want it so there it is.
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A great schema for thinking about this troubled area. My concern is that CTG technology is so deeply cemented into everyone’s anxiety centres in the brain, no amount of research will be adequate to free us from this oppression. The only future I see is in an alternative technology , which will be evaluated free of the fallacies so well outlined above.
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Do you have a sense for what might replace it? It seems to me that we have abandoned oximetry too quickly. And while we still delude ourselves thinking that CTGs are working there’s little incentive to come up with an effective alternative.
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