CTG Monitoring: The Trace That Changed Everything ….. Or Did It?
There is a moment in every birth room where the silence is broken by a machine. A paper trace begins to crawl across the screen. Black ink. Peaks and troughs. A rhythm that suddenly becomes louder than the woman herself. And just like that, the room shifts. Because once the CTG starts speaking, everyone else stops listening.
The Promise We Were Sold
Cardiotocography was introduced with a powerful promise. That we could see distress before it became disaster. That we could prevent hypoxia, prevent cerebral palsy, prevent death. A machine that could save babies. And so, we built entire systems around it. But here’s the quiet, uncomfortable truth. The evidence never quite caught up with the belief.
What the Evidence Actually Says
The most robust evidence we have, including the Cochrane review, tells a very different story. Continuous CTG monitoring during labour has not been shown to reduce perinatal mortality or rates of cerebral palsy, despite decades of use (Alfirevic et al., 2017). What it does show, consistently, is an increase in intervention, particularly caesarean sections and instrumental births (Alfirevic et al., 2017).
There is a reduction in neonatal seizures, but this has not translated into improved long-term neurological outcomes (Alfirevic et al., 2017). NICE acknowledges this directly, reinforcing that continuous CTG for low-risk women does not improve overall outcomes and should not replace intermittent auscultation (NICE, 2022). Similarly, RANZCOG recognises that while CTG has a role in higher-risk scenarios, its routine use in low-risk labour is not supported by evidence and is associated with increased intervention (RANZCOG, 2019).
Let that land for one minute. We introduced a technology to improve outcomes, and instead, we increased intervention without changing the outcomes we feared most.
So Why Does It Still Dominate the Room?
Because CTG does not just monitor babies. It changes behaviour. It changes decision-making. It changes how we see labour. It gives us something that feels like certainty in a process that has never been predictable.
And that illusion is powerful.
The Interpretation Problem: When the Trace Becomes the Truth
CTG is often spoken about as though it is objective. As though it is a clear and reliable indicator of fetal wellbeing.
But it is not. It is interpreted. And interpretation is human.
Even when clinicians follow structured frameworks such as those outlined by NICE and RANZCOG, agreement between practitioners reviewing the same CTG trace is only moderate (Ayres-de-Campos et al., 2015). That means two experienced clinicians can look at the same pattern and come to different conclusions, leading to very different clinical decisions.
One sees reassurance. Another sees risk. And in that moment, the trajectory of birth can change.
The Cost of Getting It Wrong
CTG carries a dual risk that is rarely spoken about with enough honesty. It produces false positives, where a trace appears concerning despite a well baby, leading to unnecessary intervention and surgical birth. It also produces false negatives, where a trace appears reassuring despite evolving compromise. This reflects its limited sensitivity and specificity in predicting outcomes such as hypoxia or cerebral palsy (Alfirevic et al., 2017).
Both NICE and RANZCOG emphasise that CTG must never be used in isolation for decision-making, precisely because of these limitations (NICE, 2022; RANZCOG, 2019). And yet, in practice, it so often is.
And Meanwhile… The Woman
While we watch the paper, we stop watching her. Movement becomes restricted. Positions change. Physiology shifts. The body that was working instinctively is now being managed.
NICE explicitly highlights that continuous CTG can limit mobility and may impact labour progression and maternal experience (NICE, 2022). In this way, the very tool designed to improve safety may contribute to the cascade of intervention it was meant to prevent.
CTG does not simply observe labour. It reshapes it.
Does CTG Improve Outcomes?
The honest answer is that it does not improve outcomes in the way we were led to believe.
It may identify patterns associated with potential compromise and reduce the incidence of neonatal seizures. But it does not reduce perinatal death, and it does not reduce long-term neurological injury (Alfirevic et al., 2017). What it does do is increase intervention. And that matters.
Does Midwife Interpretation Change Outcomes?
This is where the conversation must come back to us. Because while the machine is limited, the clinician is not irrelevant.
A skilled midwife does not read a CTG in isolation. She reads the whole picture. The woman’s movement, the rhythm of labour, the subtle shifts that cannot be graphed. CTG becomes one piece of information, not the defining authority.
Both NICE and RANZCOG reinforce that CTG interpretation must be contextual and supported by clinical assessment, not used as a standalone diagnostic tool (NICE, 2022; RANZCOG, 2019).
Skill matters. Experience matters. But even then, CTG remains an imperfect tool.
Where I Stand…
CTG has a place. But it is not the centre of birth. It is one piece of a much bigger picture.
And when we elevate it above the woman, above physiology, above clinical wisdom, we risk creating the very outcomes we are trying to prevent. Because birth was never meant to be managed by a trace. It was meant to be understood.
CTG should not change your practice in isolation. It should not supersede clinical observation or the broader clinical picture. It should sit alongside it. It should inform, not dictate. Because a trace without context is just a pattern on paper.
I can interpret any trace I am given. I can call an abnormal trace with reassuring features. I can call an abnormal trace with likely significant compromise. That is what we are trained to do. That is what we are examined on. But those exams, often delivered in classrooms, removed from the woman, removed from the birthing room, removed from the unfolding physiology, were never designed to reflect the complexity of real clinical decision-making. Because real birth does not happen on paper. It happens in a relationship. In movement. In nuance. And it is in that space that clinical judgement lives.
Food for Thought…..
If a tool increases intervention, but does not improve outcomes, we have to ask ourselves an uncomfortable question. Are we using it to protect birth. Or has it quietly reshaped it into something else entirely?
References (APA 7th)
Alfirevic, Z., Devane, D., Gyte, G. M. L., & Cuthbert, A. (2017). Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database of Systematic Reviews, (2), CD006066. https://doi.org/10.1002/14651858.CD006066.pub3
Ayres-de-Campos, D., Spong, C. Y., & Chandraharan, E. (2015). FIGO consensus guidelines on intrapartum fetal monitoring: Cardiotocography. International Journal of Gynecology & Obstetrics, 131(1), 13–24. https://doi.org/10.1016/j.ijgo.2015.06.020
National Institute for Health and Care Excellence. (2022). Intrapartum care for healthy women and babies (NG235). https://www.nice.org.uk/guidance/ng235
Royal Australian and New Zealand College of Obstetricians and Gynaecologists. (2019). Intrapartum fetal surveillance (C-Obs 43). https://ranzcog.edu.au