Inventing the CTG

Obstetricians as saviours

An entire century passed between the introduction of intermittent auscultation in labour (using simple devices that didn’t have electronic wizardry included) and the development of the CTG. During that time researchers and doctors tried to figure out the relationship between changes in the the fetal heart rate over time and in relation to contractions, and to relate these to the state of the baby immediately following birth. The concept of “fetal distress” emerged for the first time. The idea emerged that the fetus was at risk for bad things, and that only a clever obstetrician could determine this was happening, and offer a way to rescue the fetus. This belief proved to be an effective tool for obstetricians to gain and hang on to positions of authority in health care systems – even before the CTG came along (Arney, 1982).

Along came the technology…

Two world wars and the space race were fuelling rapid developments in electronic technology through the late 1940s and beyond. Industrialisation was driving the mass production of increasingly affordable, life enhancing, consumer objects – cars, washing machines, colour televisions, and electric typewriters emerged during the same time period. 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?

The tech boom enabled the development of recording equipment that could capture electronic impulses coming from the fetal heart and measure pressure inside a woman’s uterus. And so the cardiotocograph or CTG was born. The CTG machine arrived at a time when technology appeared to offer solutions to many problems.

Research integrity?

In 1958, Edward Hon, an Australian born obstetrician working in the USA, published his research on fetal heart rate patterns observed with an early CTG machine he had created. 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. While he was not the only researcher working on CTGs, his research played an important role in helping the new technology to gain acceptance.

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).

And then the lawyers arrived

Adding to the seductiveness of the CTG was what Sartwelle, Johnston and Arda (2016) have referred to as the “perfect storm”. CTG were being introduced at a time when there was a shift in how legal liability was being argued in the courts of most high-income countries. The birth of a child with cerebral palsy was no longer seen as a bad luck. Having a CTG trace to look back on now meant that cerebral palsy was someone’s fault. That someone could be made to pay for their actions (or inaction) through legal processes. Failure to make use of CTG monitoring rapidly became seen as bad medical practice (even though there is absolutely no proof that CTG use protects against successful litigation).

So where was the science?

Myths about obstetricians as saviours and their new focus on the fetus, rather than the woman, as their most important patient; the belief that technology could solve all the world’s problems; and the risk of ending up in court with a bad outcome were what drove the rapid spread of CTG technology around the world. By the time researchers began to put the parts of the puzzle together to show that CTG monitoring wasn’t better for the baby and was worse for their mothers – it was too late to turn back the tide. To a large extent the same stories still work to keep CTG use as an expected part of maternity care.

Obstetrics claims to be a scientific profession, one that makes use of research evidence to guide practice. But good science had almost nothing to do with the introduction of CTG monitoring. The challenge for us now is how to turn away from the use of a birth technology which is at best ineffective, and more likely harmful, to birthing women and their babies.

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References

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.