Introduction

Every human fetus who undertakes the journey of human labour which lasts for approximately 6-10 hours on average, is exposed to an inevitable and gradually progressing hypoxic stress. This is because as the woman begins contracting the uterus to expel her fetus through the bony and soft tissue parts of the maternal birth passage, spiral arterioles which traverse the myometrium to supply the placental bed are compressed, resulting in reduced utero-placental perfusion during uterine contractions. Moreover, depending on the position of the loops of umbilical cord in relation to bony fetal parts and bony maternal pelvis, and the amount of amniotic fluid and Wharton’s Jelly available to protect the umbilical blood vessels within the umbilical cord, there may be also varying degrees of umbilical cord compression during a uterine contraction. Both these mechanisms may significantly reduce fetal oxygenation, resulting in intermittent hypoxic stress which may compromise oxygenation of fetal central organs. As the uterine contractions increase in frequency, duration and strength as the labour advances, this intermittent hypoxic stress may get progressively worse, and may increase the likelihood of hypoxic-ischaemic encephalopathy (HIE) or an early neonatal death (ENND).

Fortunately, the vast majority of human fetuses are able to successfully mount effective compensatory responses to this intermittent and gradually evolving and progressive hypoxic stress. Physiological changes that enable intrauterine fetal adaptation to compensate for the relatively hypoxic intrauterine environment, that mimic “An Everest-in-Utero” [1] confer remarkable resilience on human fetuses to withstand transient and brief hypoxic episodes without sustaining any damage. This is analogous to a marathon runner who increases his/her/their heart rate and respiratory rate to ensure adequate oxygenation of their central organs in order to avoid the onset of anaerobic metabolism and the production of lactic acid. Their compensatory response to ongoing hypoxic stress whilst running a marathon may be blunted by pre-existing medical disorders (e.g., coronary heart disease, diabetes, flu), poor individual reserve to withstand hypoxic stress (e.g., age>75), increased metabolic demand (e.g., obesity, hot environmental temperature) and the speed of running (e.g., higher the speed, earlier the exhaustion).

Similarly, antenatal utero-placental insufficiency, adverse maternal environment, loss of fetal compensatory mechanisms and iatrogenic increase in uterine activity (Table 1) may blunt these compensatory responses predisposing to hypoxic-ischaemic injury with potential long term sequalae such as cerebral palsy and learning difficulties and/or perinatal deaths. These wider clinical contexts should always be considered whilst interpreting CTG traces.

The International Consensus Guideline on Physiological CTG interpretation produced by 44 CTG experts from 14 countries in 2018 [2] which was developed to aid interpretation of CTG traces to timely recognise intrapartum hypoxic stress is based on the identification of the combination and/or sequence of that indicate different types of fetal hypoxia, and determination of fetal response to ongoing stress (Table 2). In contrast, the recently updated NICE CTG Guideline continues to include arbitrary parameters grouped into “reassuring, nonreasoning and abnormal” “categories” and then randomly combining them to have an overall classification (Normal, Suspicious, Pathological) without any consideration of different types of fetal hypoxia or the fetal response to stress [3]. Such a non-physiological approach is likely to increase the risks of intrapartum-related hypoxic ischaemic encephalopathy (HIE) and perinatal deaths and/or increase the likelihood of unnecessary operative interventions for women. Therefore, in the interest of patient safety, it is vital to scrutinise the updated NICE CTG Guideline, and from a scientific perspective, ask the question: Is the NICE CTG Guideline itself is suspicious and/or pathological?

Understanding the perilous journey of UK CTG guidelines

The first CTG Guideline was produced by the Royal College of Obstetricians and Gynaecologists (RCOG) in 2001 [3]. It is extraordinary that despite CTG being introduced into clinical practice in 1968 and was being routinely in the UK labour wards, the decision to produce a national guideline on CTG interpretation took 33 years. The driving force was the shocking findings of the Confidential Enquiries into Stillbirths and Deaths in Infancy (CESDI) in1997 [4], which concluded that out of approximately 800 babies who had an intrapartum-related stillbirth in the UK, 50% had a “Grade 3 Substandard Care” (i.e., with a different care, these babies would have most likely survived), and 75% had “Grade 2 and Grade 3 Substandard Care” (i.e., they may have survived). Lack of knowledge regarding CTG interpretation was highlighted as a major factor which contributed to these potentially avoidable intrapartum-related deaths. Regrettably, despite the publication of this report in 1997, it took further 4 years to produce a national CTG Guideline in the UK [3], potentially resulting in the loss of approximately 500 babies during each year due to substandard care due to CTG misinterpretation.

It was obvious to all frontline clinicians who understood fetal physiology that the first CTG guideline classification tool (Figure 1) was deeply flawed both from scientific and common-sense perspectives (Table 3).

The categorisation recommended by the guideline was both illogical and scientifically impotent because it stated that “all 4 features should be reassuring” for the CTG trace to be classified as normal (Figure 1). However, it stated that the absence of accelerations was of “uncertain significance”. If this was the case, then, accelerations should not have been considered whilst classifying the CTG traces as “normal”. In the absence of accelerations, if there were early or variable decelerations, the CTG trace would have to be classified as “pathological”, increasing the risks of unnecessary operative interventions. Similarly, if there was a single prolonged deceleration of up to 3 minutes and an early deceleration, the CTG trace would have been classified as “pathological” warranting an unnecessary intervention. This oversimplistic and scientifically illogical approach of “mixing and matching” random features to “categorise” CTG traces as “normal, suspicious, pathological” was not only implemented in routine clinical practice, but it was also strictly and religiously audited to ensure compliance of at least 75%.

The RCOG CTG guideline was subsequently acquired by NICE as “inherited” NICE Guideline, however, no action was taken to identify and rectify the flaws (Table 3). It was not surprising that not only the rate of caesarean sections increased in the UK, but the Chief Medical Officer’s Report, titled “Intrapartumrelated deaths: 500 missed opportunities” published in 2006 highlighted CTG misinterpretation as an important contributory factor for these, very unfortunate avoidable intrapartumrelated deaths [5]. It should have been very evident to those who produced the CTG Guideline and the professional bodies who had the responsibility implement evidence-based clinical practice in the UK and to “set standards to improve women’s health” that the system of classifying the CTG traces into “normal, suspicious, pathological” had to be abandoned immediately to safeguard women and babies. There was an urgent need to implement a CTG guideline tool that is based on the deeper understanding of fetal physiology to determine the features of different types of fetal hypoxia and fetal response to ongoing hypoxic stress.

Unfortunately, not only this opportunity to rectify the flaws of CTG guideline produced in 2001 was missed, due to some inexplicable and bizarre reason, the NICE CTG guideline development group (GDG) in 2007 chose to make it even more confusing by adding arbitrary time limits to be applied to all human fetuses [Figure 2]. In addition to the flaws identified in 2001 CTG Guideline, further incorporation of unscientific time limits (e.g., decelerations for 50% of contractions for 30 or 90 minutes) not only increased the likelihood of inter and intraobserver variability which would have resulted in variation in management and resultant poor outcomes, but, it would have also contributed to poor perinatal outcomes and an increase in the rate of unnecessary operative interventions [Table 4]. It was not surprising that within 2 years of publication of this confusing guideline with no consideration to fetal responses to stress or features of intrapartum hypoxia, the NHS Litigation Authority (NHSLA)’s Study on Stillbirth Claims highlighted that 34% of all successful clinical negligence claims against the NHS on stillbirths were due to CTG misinterpretation [6]. However, no actions were taken to rectify these very obvious errors (Table 4), despite the knowledge that 34% of babies died solely due to CTG misinterpretation. There was no attempt by professional bodies who had the responsibility to promote evidence-based practice to stop the unphysiological, confusing, CTG guideline with arbitrary, personal opinion-based time limits which was contributing to CTG misinterpretation.

NICE CTG Guideline in was revised again in 2014 [7] following the publications of 10 years of Maternity Claims by the NHSLA in 2012 [8], which highlighted the financial and clinical burden and the human costs of CTG misinterpretation on babies, women and their families. Many consider that NICE 2014 CTG Guideline was one of the worst and the most dangerous of all the CTG Guidelines produced not only in the UK, but in the world. This guideline not only recommended “oral fluids” to treat suspicious and pathological CTG traces without even considering the time taken for absorption of water during labour to treat ongoing CTG abnormalities, but also included several recommendations solely based on the personal opinions of those in the GDG without, or contrary to scientific evidence and basic physiological principles, increasing the risks of maternal and perinatal morbidity and mortality. Furthermore, this CTG guideline openly advised obstetricians to hide the information derived from scientific evidence on FBS from women. Alarmingly, despite concluding based on the review of scientific evidence, that FBS increased the rate of emergency caesarean sections and operative vaginal births, it recommended that women should be advised exactly the opposite: that FBS may reduce the need for further interventions [7]. Although this blatant lack of regard to “Duty of Candour” (a legal requirement in the UK) by the NICE CTG Guideline Group was questioned [9], no action was taken to rectify this recommendation. Women were continued to be provided with incorrect, and misleading information contrary to available scientific evidence, and were not informed that the test that was being performed on their babies did not improve their perinatal outcomes, but FBS has been shown to significantly increase their emergency caesarean sections and operative vaginal births. If honesty and openness had prevailed, and the correct information was given as in other specialties of clinical medicine in the UK, it was very likely that most women would have declined FBS.

Fortunately, for the first time in the history of intrapartum care, the labour ward lead consultants from 19 hospitals in London formed the “Pan London Labour Ward Leads Group” and they signed a joint letter to the President of the Royal College of Obstetricians & Gynaecologists (RCOG), expressing their concerns. Very unfortunately, no action was taken by the professional bodies prior to the intervention of the Pan London Labour Ward Leads group despite the obvious fact that if this flawed CTG guideline was implemented, both maternal and perinatal outcomes would significantly worsen resulting in disastrous consequences to women, their babies and families as well as to frontline midwives and obstetricians. It was not surprising that the Each Baby Counts Report in 2015 highlighted that out of 1136 babies who died or sustained severe brain damage, in 76% a different care might have made a difference to the outcome (10). Moreover, issues with CTG interpretation and FBS contributed to 61% of all cases of poor outcomes [10].

Unfortunately, it took almost 3 years for NICE to finally revise the guideline in 2017 due to “stakeholder concerns” [11], which resulted in the same errors being perpetuated for 3 years, resulting in disastrous consequences for babies, women and their families. This was evidenced by subsequent Each Baby Counts Report concluding that even in 2016, issues with CTG interpretation and FBS continued to contribute to 60% of poor outcomes [12]. Although, there was evidence from Cochrane Systematic Review from 2013 that FBS did not improve long term perinatal outcomes and did not reduce intrapartum operative interventions [13], and commentaries in the “College Journal” highlighting the dangers [14,15], no action was taken to rectify the error either by the professional bodies or by NICE. This resulted in issues with CTG misinterpretation and FBS continuing to contribute to approximately 60% of severe hypoxic-ischaemic encephalopathy and perinatal deaths even in 2019 [16], and 2020 [17]. The fact that FBS was continued to be recommended by the NICE GDG in 2017 despite of scientific evidence showing benefit, and in fact, scientific evidence from 2015 suggesting that repetitive FBS resulted in doubling of caesarean sections [18] illustrates that personal opinions were prioritised over evidence-based medicine by those who produced CTG guidelines in the maternity service in the UK. It was alarming that despite a UK multi-centre trial in 2019 concluding that FBS did not improve perinatal outcomes, and it had increased intrapartum emergency sections by approximately 60% [19], no action was taken by either professional bodies or NICE to immediately stop the FBS to safeguard women and babies from avoidable harm.

Recently revised & updated NICE CTG guideline (Dec 2022)

The revised NICE CTG Guideline finally stopped recommending FBS due to “lack of evidence” [20], although issues with CTG interpretation and FBS had already contributed to significant patient harm (Figure 3). Several illogical, scientifically impotent and clinically dangerous clinical practices such as administering fluids to the mother which, according to the NHS Resolution Report increased the risks of maternal deterioration and neonatal convulsions [21] were finally stopped by this “revised & updated” NICE CTG Guideline in 2022. Fortunately, this “revised and updated” guideline finally rectified the unscientific and dangerous increase in the threshold of abnormal baseline FHR used in the UK from 2001 (i.e., 180 bpm instead of 160 bpm as per all other international guidelines from 1987) which, most likely had contributed to severe brain damage and deaths of babies in the UK for 21 years.

However, it was regrettable and unacceptable from a patient’s safety perspective that professional bodies had turned a blind eye to administering of fluids to the wrong person (i.e., mother) for presumed “suspicious” or “pathological CTGs” until December 2022. Patient centred clinical practice demanded that this illogical practice to have ended much sooner than in 2022. Our patients would have expected that frontline clinicians abandon this unscientific, illogical and potentially harmful practice immediately after the publication of the NHS Resolution Report in 2019 [21] which highlighted the risks of maternal deterioration and neonatal convulsions due to excessive administration of fluids to the mother during labour, dilutional hyponatremia and fluid overload. At the very least, the patients would have expected this potentially dangerous practice to stop immediately after the publication of a Commentary highlighting these risks in 2020, in an open access journal which did not require any subscription fees to access [22].

Regrettably, the fundamental flaws in the NICE CTG guideline which had most likely resulted in harm to babies and women were not rectified even in 2022 [20]. This guideline continued to classify CTG traces into “Normal, Suspicious, Pathological” by randomly grouping certain “features” into different “categories without considering the combination of / sequence of fetal heart rate changes which indicate ongoing fetal hypoxia or features of fetal compensatory response (Table 5). Perpetuating the same errors with regard to the classification of CTG traces into “normal, suspicious and pathological” without considering the type of fetal hypoxia and the features of fetal response to stress, since 2001, despite publications in Open Access Journals (i.e., does not require a subscription fee for the NICE CTG GDG to access) in 2016 [29] is indeed very unfortunate. These flaws in the NICE CTG Guideline were again highlighted in an Invited Commentary in the Journal of Patient Safety and Risk Management in 2019 [31]. From a patient safety perspective, it is very alarming that guideline group had chosen to continue to focus on the morphological appearance of decelerations and grouping arbitrary CTG features with unscientific, illogical time-limits into “normal, suspicious, pathological”.

Bizarrely, the updated and revised NICE CTG Guideline appears to have simply lifted “How is this fetus?” which was highlighted in Physiological CTG Masterclasses from 2012, and then translated into several languages, and was also highlighted in several publications [31,32]. Their attempt at introducing “How is the baby?” in conjunction with the use of “normal, suspicious, pathological” classification [33] is scientifically amusing at best, and potentially dangerous at worst. It is scientifically amusing because anyone who understands basic fetal physiology to recognise the types of fetal hypoxia and the CTG features of fetal compensatory responses, and asks the question “How is the baby?” would not arbitrary group CTG features into “normal, suspicious. Pathological”. This is because “How is the Baby?” due to understanding of fetal physiological responses and “normal, suspicious, pathological” classification due to the lack of understanding of fetal physiological responses, are mutually exclusive. One cannot classify a CTG trace as “suspicious” (i.e., not sure of the significance of observed CTG features) and then ask the question “How is the baby?” because there are no “suspicious” fetuses. On the other hand, simply transposing some principles from Physiological CTG Masterclasses, without fundamentally changing the CTG interpretation tool-based knowledge of fetal physiology may lead to confusion resulting in poor maternal and perinatal outcomes. Although, there have been several publications on Physiological Interpretation of CTG prior the publication of the revised NICE CTG Guideline [34-54], including improvement in outcomes following the implementation of Physiological Interpretation of the CTG [55-61], it is indeed regrettable that this revised guideline has disregarded these principles of physiological CTG interpretation. Merely lifting “How is the Baby?” alone from Physiological CTG Masterclasses [33] will not result in improvement in maternal and perinatal outcomes, if the “normal, suspicious, pathological” classification system is continued to be used.

The price of repetition of errors involving CTG interpretation

Albert Einstein once said “insanity is repeating the same processes again and again, and expecting different results”. In the UK the same, unscientific “Normal, Suspicious, Pathological” classification system which failed to individualise care was introduced in 2001, and then, repeated in 2007, 2014, and 2017, with disastrous consequences to babies and their families. These have been highlighted in the Chief Medical Officer’s Report (2006), NHSLA Report on Stillbirth Claims (2009), NHSLA 10 years of Maternity Claims (2012), and four consecutive Each Baby Counts Reports (2015-2019). As Albert Einstein stated many years ago repeating the same (flawed) CTG classification system (“normal, suspicious, pathological) again and again has not resulted in improvement in perinatal outcomes. In an advanced economy which prides itself of having a “world class maternity service”, it is no longer acceptable to have lack of knowledge leading errors due to CTG interpretation to contribute to more than 50% of babies sustaining severe brain injuries or dying due to an intrapartum-related death.

Unsurprisingly, UK public have now demanded criminal prosecution against those who contributed to poor perinatal outcomes (https://www.independent.co.uk/news/health/ east-kent-maternity-baby-deaths-b2206143.html), and more recently they have demanded an independent public enquiry (https://www.theguardian.com/society/2023/oct/31/parentsof-babies-who-died-or-were-harmed-in-nhs-care demand-inquiry). This is understandable because, as frontline midwives and obstetricians, if our own babies are brain damaged or died during labour due to an erroneous guideline which classified fetal heart rate traces into “normal, suspicious, pathological” without incorporating fetal physiology, and then recommended to administer fluids to the mother for suspicious CTGs and erroneously recommended to cut the skin of our own babies’ scalp check for oxygenation of the fetal brain, then, most likely we would demand criminal prosecution and a public enquiry too. Parents have the right to be shocked when they eventually find out that in the UK, not only it was almost universal to have rolls of “CTG Stickers” with exactly the same parameters which were used in every human fetus, irrespective of the individual fetal reserves or clinical context, the use of these “stickers” were rigorously audited to ensure >75% compliance. This resulted in the strict enforcement and implementation of the wrong tool which was causing patient harm, and financial incentives (discounts for the insurance premium) were provided for demonstrating that there was progress towards 100% of using these wrong CTG tools.

At the time of writing this commentary, the degree of harm caused to women as a result of CTG interpretation have not been monitored or reported. Currently, clinicians have absolutely no idea of the number of women who had massive postpartum haemorrhage, wound complications or died due serious complications such as uterine rupture or placenta accrete spectrum disorders in subsequent pregnancies due to an unnecessary caesarean section being performed for a “pathological CTG” or following an “abnormal” FBS result (which reflected normal acidosis in the peripheral tissues due to centralisation of blood flow to compensate for the ongoing hypoxic stress). Similarly, one has no idea about the rate of perineal tears and trauma sustained by women due to an unnecessary operative vaginal birth due to a “pathological CTG” during the second stage of labour. There is no doubt that the general public would want to investigate these maternal complications in the near future.

The way forward: need for the “Self-Candour Test”: The Hippocratic Oath stipulates “first do no harm” and “acting in the best interest of our patients” as key cornerstones of good medical practice. Therefore, in the interest of patient safety, honesty and ensuring our clinical practice is based on current scientific evidence and scientific principles, frontline clinicians should consider the “Self-Candour Test” (Table 6) prior to implementing the updated and revised NICE CTG Guideline in their own clinical practice. If the answer to any of these questions in Table 6 (especially Question 5) is “No”, then, it is important to practice the “Duty of Candour” and understand the principles of Physiological Interpretation of CTG [34-54,62-63], and to provide patients with an evidence-based, scientifically acceptable clinical care.

Table 1: Potential causes which may contribute to, and/or accelerate fetal compromise.

Table 2: CTG Classification based on International Expert Consensus Guidelines on Physiological Interpretation.

Table 3: Flaws in the RCOG CTG Guideline produced in 2001.

Table 4: Flaws in the NICE CTG Guideline (2007) – in addition to the continuation of the flaws highlighted in Table 3.

Table 5: Flaws in the “Updated & Revised” CTG Guideline 2022.

Table 6: The “Self-Candour Test”.

Conclusions

The “updated & revised” NICE CTG Guideline has finally stopped FBS and the administration of fluids to the mother for the treatment of suspicious and pathological CTG traces, after 21 years of introducing these potentially dangerous, illogical clinical practices in the UK. However, it has continued to use the same “normal, suspicious, pathological” classification system without incorporating the features of different types of fetal hypoxia, the features of fetal compensatory responses and the features of fetal neuroinflammation seen in chorioamnionitis which is an important pathway of fetal neurological injury. Therefore, in the author’s opinion, the NICE CTG Guideline (2022), similar to its precursors from 2001, 2007, 2014 and 2017, continues to remain suspicious with regard to the knowledge of fetal physiology, with the potential to cause pathological outcomes for women and babies.

Declarations

Conflict of interest: The author has conducted several Master classes on CTG and fetal ECG in the UK, Europe, Asia, and Australia and has been the co-organizer of the Intrapartum Foetal Surveillance Course at the Royal College of Obstetricians and Gynaecologists (RCOG) and he was a member of the Editorial Board for NHS e-learning on CTG. He pioneered physiological interpretation of CTG in 2006, including the concept of “How is THIS Fetus?” to determine fetal central organ oxygenation. He was the Course lead for the Neoventa Academy and the Baby Lifeline Physiological CTG Masterclasses. Organizers and hospitals of some of these Masterclasses have received sponsorships from Philips, Neoventa, Euroking, Huntleigh, K2, Cardiac Services, and other industry to support these Masterclasses. However, the author does not have any financial or managerial interests in any of these organisations. The author was one of the 3-member guideline development group which revised the international FIGO Guidelines on CTG in 2015, and he was on the Editorial Board which produced the first International Consensus Guidelines on Physiological Interpretation of CTGs in conjunction with 44 CTG Experts from 14 countries.

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