Introduction

Two hospitals in the UK have recently faced criminal charges for early neonatal deaths due to substandard care, and have been successfully prosecuted and had to pay a heavy fine. This was the first time in the history of the UK National Health Service (NHS) that a hospital had faced such a criminal charge for an intrapartum-related perinatal death. In order to understand the underlying reason behind cardiotocography (CTG) misinterpretation contributing to such perinatal deaths or severe hypoxic–ischaemic brain injury, one needs to travel back in time to the 1960s.

Cardiotocography was first introduced to clinical practice in the late 1960s, without any prior randomized controlled clinical trials or any robust scientific studies to confirm its efficacy, very unfortunately. Therefore, it was not possible to produce evidence-based guidelines on how to use this new technology at the time of the introduction of CTG into clinical practice. This situation resulted in some obstetricians in the late 1960s and early 1970s reacting to various patterns observed on the CTG trace without understanding the pathophysiological mechanisms behind these observed features or their significance regarding predicting poor perinatal outcomes. As a result of the undue influence of some very powerful obstetricians from some professional bodies, unscientific and illogical guidelines with arbitrary time limits and nonsensical grouping of ‘features’ into different categories (‘reassuring’, ‘non-reassuring’, and ‘abnormal’) and then making an overall classification into ‘normal’, ‘suspicious’, and ‘pathological’ without considering fetal response to stress or the different types of fetal hypoxia had slowly but surely crept into clinical practice.

The early CTG ‘experts’ classified CTG traces solely based on pattern recognition by determining various features observed on the CTG trace [e.g. baseline fetal heart rate (FHR), baseline variability, presence of accelerations and decelerations] and concentrating on the morphology of these decelerations, and then recommended the same guideline with arbitrary parameters to be applied in all human fetuses. They failed to appreciate that a fetus with intrauterine growth restriction cannot be expected to withstand ‘atypical’, ‘complicated’, or ‘late decelerations’ for 50% of contractions for 30 minutes as compared to a term, well-grown fetus. Similarly, they failed to appreciate that fetuses with non-hypoxic causes of fetal compromise such as chorioamnionitis cannot be subjected to the same CTG guidelines, which were predominantly focused on the morphological appearance of ongoing decelerations. This illogical and unscientific approach based on ‘expert’ opinions resulted in an exponential increase in caesarean sections without any concomitant reduction in cerebral palsy or perinatal deaths.

The first recognized guideline on CTG interpretation was published by the American College of Obstetricians and Gynaecologists (ACOG) in 1979, and this was followed by the international guidelines on CTG interpretation published by the International Federation of Gynecology and Obstetrics (FIGO) in 1987. Due to the ongoing confusion and diverse ‘expert opinions’ without any robust scientific evidence to support these opinions, there are currently more than 20 national CTG guidelines on how to interpret the CTG traces, and several repetitive revisions of the CTG guidelines due to ongoing confusion. Lack of understanding of the pathophysiology of intrapartum hypoxia as well as randomized controlled trials resulted in obstetricians merely exhibiting a ‘panic reaction’ to observed decelerations on the CTG trace, which were initially termed ‘type 1’ and ‘type 2’ decelerations, and then subsequently ‘early’, ‘variable’, ‘late’, ‘typical’, ‘atypical’, ‘complicated’, ‘uncomplicated’, ‘reassuring’, or ‘non-reassuring’, without any consideration to determination of features that are suggestive of fetal compensatory responses or fetal decompensation.

The Impact of Cardiotocography Misinterpretation

In 1971, Beard et al. (see Reference 1 in the list of Further Reading) reported that even when significant abnormalities (e.g. late decelerations and complicated baseline bradycardia) were noted on the CTG trace, more than 60% of fetuses had a normal scalp pH (>7.25). This very high false-positive rate of CTG (60%) indicated that of 100 caesarean sections performed for suspected fetal compromise, 60 were potentially unnecessary. However, due to a paucity of knowledge concerning fetal acid–base balance during labour in the late 1960s and 1970s, it was thought, purely based on personal opinions of a few senior obstetricians, that if the fetal scalp pH was 7.25 or less, ‘it is considered possible that the fetus was asphyxiated’.

Subsequent large observational studies have refuted this erroneous assumption, and it is now well known that a cord arterial pH of less than 7.0 (and not a skin pH of 7.25) is associated with poor perinatal outcomes. Therefore, if a cut-off of 7.0 was used instead of 7.25 by Beard et al. in 1971, it was very likely that the false-positive rate of CTG would have been over 99%. This implies that, if pattern recognition is used for CTG interpretation without understanding the fetal physiology, 99 of 100 emergency caesarean sections performed for suspected fetal compromise would be entirely avoidable. In fact, Karin Nelson et al., based on a large study of >150,000 fetuses, concluded that even in the presence of repetitive late decelerations, and reduced baseline FHR variability, the false positive rate of a pathological CTG trace was 99.8% (see Reference 28 in the list of Further Reading).

More importantly, many CTG guidelines that are focused on the depth and duration of decelerations as ‘pathological’ would miss fetuses with chorioamnionitis and chronic hypoxia, leading to rapid fetal decompensations resulting in neurological injury or perinatal deaths. It is very likely that the clinicians at Nottingham University Hospital in the UK, which was recently fined £800,000 for a neonatal death, had misclassified the CTG trace as ‘suspicious’, missing the features of acute chorioamnionitis on the CTG trace. Had they considered the features of neuroinflammation instead of using a CTG guideline that was mainly based on the morphological appearance of decelerations without considering the phenomenon of cycling or >10% increase in the baseline FHR, on the balance of probabilities, this very unfortunate neonatal death would have been avoided.

Cardiotocography misinterpretation has an adverse impact on babies, women, their families as well as the society. However, one should not forget the psychological impact on healthcare providers who have been involved in a case of cerebral palsy or perinatal death as a result of CTG misinterpretation. The fourth ‘Confidential Enquiries into Stillbirths and Deaths in Infancy’ (CESDI) reported in 1997 that more than 50% of intrapartum-related stillbirths were due to ‘grade 3’ substandard care, and, therefore, approximately 400 of 873 stillbirths were potentially avoidable by an alternative management. Lack of knowledge in the interpretation of CTG traces, failure to incorporate the entire clinical picture (meconium, maternal temperature, chorioamnionitis, etc.), delay in intervention even after recognizing an abnormality on the CTG, as well as communication and commonsense issues were the key identified areas in cases with substandard care.

The Chief Medical Officer’s report in the UK in 2006 titled ‘Intrapartum-Related Deaths: 500 Missed Opportunities’ highlighted similar issues relating to substandard care even 10 years after the CESDI report in 1997. This was followed by the National Health Service Litigation Authority’s (NHSLA) report on ‘100 Stillbirth Claims’ in 2009, which highlighted the fact that 34% of stillbirth claims involved CTG misinterpretation. In addition to poor perinatal outcomes and long-term neurological sequelae, CTG misinterpretation is also associated with significant medicolegal costs. Ennis and Vincent reported issues relating to poor record-keeping and storage of CTG traces as contributory factors (see Reference 11 in the list of Further Reading).

The NHSLA’s ‘10 Years of Maternity Claims’ report highlighted the medicolegal implications of CTG misinterpretation, which contributed not only to claims arising from cerebral palsy and stillbirths but also to complications arising out of emergency caesarean sections. One should not disregard the findings of Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries Report (MBRRACE, 2018; see Reference 21 in the list of Further Reading), which concluded that there has been a near doubling of maternal deaths due to postpartum haemorrhage in that triennium and placenta accreta was the leading cause. Therefore, there is an urgent need to stop emergency caesarean sections performed for ‘pathological CTG’ or ‘abnormal fetal blood sampling’ to safeguard women and babies.

Failure to recognize an abnormal CTG, failure to incorporate clinical picture, failure in communication, and injudicious use of oxytocin infusion were highlighted as key contributory factors to medicolegal claims. It was reported that the overall cost of medicolegal claims was over £3 billion in 2017. However, a more recent NHS Resolution Report (2022) has confirmed that this has doubled over the last 5 years to approximately £7 billion. This accounts for 60% of the total NHS claims (£13.6 billion) in 2021/2022. The issues relating to CTG misinterpretation are not unique to the UK. Publications from Norway have suggested that substandard care is common in birth asphyxia cases, and human error is the most common contributory factor. Similar publications from Sweden have highlighted that injudicious use of oxytocin in labour was associated with approximately 70% of all medicolegal claims. The author’s own medicolegal practice suggests that misinterpretation of the CTG trace as well as inappropriate management of labour contributed to approximately 70% of all cases of cerebral palsy and perinatal mortality, which were potentially avoidable by an alternative management. In addition, poor CTG interpretation may lead to an unnecessary intrapartum operative intervention such as fetal scalp blood sampling (FBS), operative vaginal deliveries, as well as emergency caesarean sections, all of which are associated with potentially serious maternal and fetal complications. The knee-jerk reaction of some obstetricians to mask their lack of knowledge of fetal physiology with an anatomically and physiologically nonsensical and scientifically impotent test (FBS) is regrettable, and there is little doubt that it will be judged as one of the most harmful interventions in obstetric practice by future generations of midwives and obstetricians.

Fetal scalp blood sampling was developed by Erich Saling in Germany in 1962 as an alternative to Pinard’s stethoscope, and was never validated as an additional or adjunctive test to the CTG prior to its introduction into clinical practice. The skin of the fetal scalp is a peripheral non-essential tissue, and it should have been very obvious that a sample of blood taken from this tissue, which readily undergoes catecholamine-mediated vasoconstriction to divert blood to the fetal central organs and which is also compressed during labour (i.e. caput and moulding), was never going to reflect the oxygenation of the fetal brain. Moreover, in chorioamnionitis, vasodilation of peripheral vessels due to vasoparalysis by bacterial toxins and inflammatory cytokines will increase the blood flow to the skin of the scalp, resulting in a false-negative result, leading to false reassurance and worsening ongoing fetal compromise and to a delay in accomplishing birth. However, despite this knowledge from the basic physiology one learnt in medical school, although FBS was discontinued in the USA approximately 30 years ago, some CTG ‘experts’ and national guideline bodies in the European continent continued to advocate FBS. The historically flawed thinking that due to the proximity of the fetal scalp to the fetal brain, a sample of blood from the skin of the fetal scalp would reflect the oxygenation of the fetal blood is not even supported from an anatomical perspective. This is because the skin of the fetal scalp is mainly supplied by the branches of the superior temporal artery, which arises from the external carotid artery, whereas the brain is supplied by branches of the internal carotid and vertebral arteries (the Circle of Willis). In the author’s medicolegal practice as an obstetric expert witness, several poor maternal and perinatal outcomes have been observed due to obstetricians and midwives blindly relying on FBS, despite the knowledge of the anatomy, physiology, and repeated Cochrane systematic reviews highlighting the lack of any benefit of FBS.

Unfortunately, due to the lack of basic knowledge of fetal physiology, decelerations (which are fetal reflex responses to protect the myocardial workload to continue maintaining aerobic metabolism) were thought to be ‘abnormal’ or ‘pathological’ based on their morphological appearance or due to an arbitrarily chosen time limit. Therefore, the misclassification of normal fetal compensatory responses as ‘pathological’ resulted in an exponential increase in the rate of emergency caesarean sections and operative vaginal births without any demonstrable reduction in cerebral palsy or perinatal deaths. Trainee obstetricians were trained or coerced to perform an FBS for a ‘pathological’ CTG despite evidence from the Cochrane Database of Systematic Reviews from 2013 confirming that FBS neither reduced operative interventions nor improved long-term perinatal outcomes. This was done mainly to buy time to cover the lack of understanding. It is reassuring that FBS is the first intervention that has been abolished in all maternity units that had implemented physiological interpretation of CTG. This illustrates the empowerment of knowledge of fetal physiological responses in improving outcomes.

Recent reports into Shrewsbury Maternity Unit (The Ockenden Report) and the East Kent Maternity Unit (The Bill Kirkup Report, Part 2) are just tips of the iceberg of potential future medicolegal liability. The Nottingham Maternity Scandal has already reported to have over 100 families who could have experienced an avoidable injury or death. As this hospital had used the CTG tool that classified CTG traces as ‘normal, suspicious, and pathological’, and had used FBS for ‘pathological’ CTGs without considering the fetal physiological response to stress or individualization of care, it will not be surprising that CTG misinterpretation will be an important finding, similar to all previous reports.

Therefore, it is hoped that the physiological approach promoted by this book with deeper understanding of fetal physiological responses to hypoxic, non-hypoxic, and mechanical stresses will help individualization of care and reduce the financial burden of litigation in healthcare systems around the world. More importantly, it will help avoid the enormous human costs to the babies, women, and their families as well as to our colleagues who have chosen our noble specialty involved in bringing a new human life into this world. It is reassuring that since the publication of the first edition of this book, several hospitals have implemented physiological interpretation of CTG and have demonstrated approximately 50% reduction in the rate of intrapartum hypoxia-related severe hypoxic–ischaemic brain injury and perinatal deaths. We hope this second edition will help in our journey to eliminate medicolegal issues due to CTG misinterpretation by promoting a deeper understanding of the knowledge of fetal physiology.

The latest NHS Resolution Annual Report & Accounts (2023/24) has highlighted the fact that the maternity service contributed to 62% of the total clinical negligence provision (£58.5 billion) of the NHS and 49% of the total (£5.1 billion) clinical negligence cost of harm was contributed by the UK maternity service in 2023/24 (i.e. in one year). This translates to approximately £6.84 million paid out every day due to clinical negligence in the UK ‘world-class’ maternity service, with CTG misinterpretation and resultant cerebral palsy, learning difficulties, and perinatal deaths being the major contributor to this ‘financial bleeding’ of the NHS. Although immediate attention often focuses on the financial burden on UK taxpayers, one should not forget or disregard the human costs on women, birthing people, and babies who have suffered immensely due to avoidable harm due to the long-term, life-changing consequences of CTG misinterpretation. Blind adherence to national guidelines and performing FBS or emergency caesarean sections for presumed ‘pathological’ CTG trace which has a false-positive rate of 99.8% has resulted in unnecessary intrapartum interventions such as emergency caesarean sections and vacuum and forceps births, with their resultant direct complications (postpartum haemorrhage, sepsis, venous thromboembolism, placenta accreta spectrum disorders, perineal trauma) as well as posttraumatic stress disorder (PTSD). The recent report on Birth Trauma, including the parliamentary debate on this matter, illustrates the impact on undertaking unnecessary operative vaginal births due to a presumed ‘pathological CTG’ or an abnormal FBS result during the second stage of labour due to the lack of basic knowledge of fetal physiology.

From an ethical and Duty of Candour perspective, informing women/birthing people that their fetus is ‘in distress’ or ‘compromised’ because of a ‘pathological CTG’ trace or an abnormal FBS result should not be tolerated in any patient-centred healthcare system that is founded on honesty. This is because a pathological CTG has a reported false-positive rate of 99.8% (i.e. >98% likelihood that the fetus was NOT in ‘distress’) and an abnormal FBS result, in the vast majority of cases, indicates an effective centralization of oxygenated blood by catecholamine-mediated vasoconstriction of the skin of the scalp (i.e. a fetal compensatory response and not ‘fetal distress’). It is unsurprising that families who lost their babies have stated that ‘they have been lied to’ and have now demanded criminal prosecution (www.independent.co.uk/news/health/east-kent-maternity-baby-deaths-b2206143.html). Therefore, frontline midwives and obstetricians must be honest and should no longer inform women and birthing people that ‘pathological’ CTG traces and ‘abnormal FBS’ results reflect ‘fetal distress’ and tell them the truth that there is a 99.9% probability that their baby was absolutely normal and, therefore, no obstetric intervention is necessary based on application of the knowledge of fetal physiology. The fact that, more recently, 70 families have decided to conduct their own investigation into baby deaths (https://tinyurl.com/4ydwzfw6) illustrates the unfortunate lack of trust between clinicians, healthcare providers, and our patients due to many years of not adhering to the legal requirement of Duty of Candour, especially regarding the use of unscientific tools for intrapartum CTG interpretation (with an illogical ‘normal, suspicious, pathological’ classification system), and FBS (which was stopped in the USA due to lack of scientific evidence of benefit; subsequent studies from 2015 suggest that FBS increased the rate emergency caesarean sections without improving perinatal outcomes, and continued to be used in the UK until 2022). The most a recent Confidential Enquiries into Maternal Deaths in the UK (October 2024) has highlighted that 44% of women who died after giving birth due to venous thromboembolism had a caesarean section, which signifies the urgency to reduce unnecessary intrapartum caesarean sections performed due to ‘pathological CTGs’ and ‘abnormal FBS’.

It is very much hoped that this book, which has moved away from the illogical, unscientific, and potentially dangerous ‘normal, suspicious, pathological’ classification from its first publication in 2017 and is based on the principles of physiological interpretation of CTG, in line with the International Expert Consensus Statement published by more than 50 CTG experts from over 20 countries in 2024, will continue our journey to reduce avoidable harm to women, birthing people, their babies, and their families. Let’s hope that providing honest and objective information to our patients based on the application of scientific knowledge regarding fetal well-being while interpreting CTG traces will restore the trust between clinicians and families, who feel that they have been lied to by their clinicians and healthcare providers. We owe this to women, birthing people, their babies, and their families, who have placed their trust in us to provide evidence-based clinical care based on scientific foundations and the application of the knowledge of fetal pathophysiology.