Birth Small Talk

Talking about birth

The invention of the CTG machine: the history of fetal heart rate monitoring

During the century between the introduction of auscultation in labour, and the development of the CTG, obstetricians began to describe and categorise changes in the pattern of the fetal heart rate over time and in relation to contractions, and to correlate these to the state of the baby immediately following birth. The concept of “fetal distress” emerged, and the fetal distress meta-narrative was put to use to establish and retain obstetric authority in maternity systems in most high-income countries (Arney, 1982).

Rapid developments in electronic technology, fuelled by two world wars and the space race, enabled the development of recording equipment that could capture electronic impulses coming from the fetal heart and measure pressure inside the birthing woman’s uterus. Thus, the cardiotocograph or CTG was born. In 1958, Edward Hon, an American obstetrician, published his research on fetal heart rate patterns observed with an early CTG machine. Hon continued to investigate the various patterns that could be seen in the fetal heart rate tracing generated by the CTG, and how they related to the problem of “fetal distress” over the next few decades. What was not made clear at the time that he was publishing, was that he was the founder of Corometrics Medical Systems, one of the first companies to produce CTG machines for commercial use. Hon and his co-researchers benefitted significantly from the widespread use of CTG monitoring, promoted by their research findings. Current attitudes towards research integrity would see this as a significant conflict of interest (Sartwelle, Johnston, Arda, & Zebenigus, 2019).

The CTG machine arrived at a time when technology appeared to offer solutions to many problems. Industrialisation was driving the mass production of increasingly affordable, life enhancing, consumer objects – cars, washing machines, mobile phones, colour televisions, and even the first Apple computer emerged during the same time period as the creation and refinement of the CTG. For those who could afford them, these objects were quickly accepted as essential parts of modern life. Why not make use of technology in the birth room as well?

Compounding the lure to make use of the CTG was what Sartwelle, Johnston and Arda (2016) have referred to as the “perfect storm”. The introduction of the CTG coincided with the liberalisation of legal liability in the courts in most high-income countries. The birth of a child with cerebral palsy was no longer seen as an unfortunate circumstance. It was someone’s fault, and that someone could be made to pay for it through legal processes. Failure to make use of CTG monitoring rapidly became seen as indefensible practice. 

Coupling the fetal distress meta-narrative with technology, as the CTG machine did, created a very seductive combination. CTG machines appeared to offer a technological and rational means to achieve the goal of a live, healthy baby at the end of every woman’s pregnancy. Having made this promise to society, obstetricians became legally culpable whenever they failed to deliver on this guarantee. The CTG was seen as a means of guarding against an unfavourable trial outcome, making concerns about the wellbeing of the mother and baby no longer the first goal of CTG use. It is not surprising therefore that the use of CTGs spread rapidly through high-income countries and became established as a cornerstone of obstetric practice, well before obstetrics began to gather scientific evidence regarding the effectiveness of CTG monitoring. 

Obstetrics claims to be a scientific profession, one that makes use of research evidence to guide practice. Yet it is easy to see from the history of fetal heart rate monitoring that research evidence had very little to do with the introduction of CTG monitoring. The challenge for contemporary practitioners is how to “dis-invest” from the use of a birth technology which is at best ineffective, and more likely harmful, to birthing women and their babies. 

Arney, W. R. (1982). Power and the profession of obstetrics. Chicago, IL: University of Chicago Press.

Hon, E. H. (1958). The electronic evaluation of the fetal heart rate. American Journal of Obstetrics and Gynecology, 75(6), 1215-1230.

Sartwelle, T. P., Johnston, J. C., & Arda, B. (2016). Electronic fetal monitoring, cerebral palsy litigation, and bioethics: The evils in Pandora’s box. Journal of Pediatric Care, 2(2), 14.

Sartwelle, T. P., Johnston, J. C., Arda, B., & Zebenigus, M. (2019). Cerebral palsy, cesarean sections, and electronic fetal monitoring: All the light we cannot see. Clinical Ethics, 45, 1-8.

Categories: CTG, EFM, History

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  1. Back to basics – Birth Small Talk

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