History of fetal assessment.

Fetal health has never been easy to assess. The first indicators were maternal perception of movement. Before it was possible to routinely detect the fetal heart, a major concern for accoucheurs was the diagnosis of fetal death, which inevitably led to a search for evidence of fetal pulsation or heart sounds. As early as the middle of the 19th century Schmidt (1858, cited by Gultekin-Zootsmann 1975) recommended to count the heart rate as often as possible from the beginning until the termination of the delivery during and between contractions to detect possible fetal problems.

Auscultation improved with the inventions of various fetal stethescopes such as the Pinard stethescope. In exceptional, more recent circumstances, uterine radiography was even used ( Stewart and Kneale, 1970).

Whilst it is documented (Schmidt and McCartney, 1999) that the Swiss physician Mayor first auscultated the fetal heart in 1818, there is evidence to suggest that it was evident as far back as 1600 by Marsac and Phillipe Le Goust ( Pinkerton 1968). Around 1650 , Marsac, claimed in one of his poems to hear the heart of the foetus beating “like the clapper of a mill” (Gunn &Wood 1953 cited by Pinkerton 1968).

It is generally agreed that bradycardia as a sign of fetal distress was noted at least as early as 1893 (Von Winckel F. 1893 cited by Hon 1959) if not earlier. Attention was drawn to the association of fetal bradycardia and poor fetal outcome. In 1895, Adolphe Pinard, a French obstetrician invented his device, known as the Pinard Horn or Pinard stethescope, which was universally used by UK midwives until it was replaced by modern Doppler devices.

During the first half of the 20th century monitoring the fetal heart during labour seems to have evolved in ad hoc ways. 

Adolphe Pinard

Fitzgerald and McFarlane (1955) outline several recommendations for the routine detection of fetal distress. These include: 

“The foetal heart sounds should not be noted merely as " F.H.H." or " foetal heart heard," as is a common practice, but the rate should always be counted at each observation. …., a foetal heart chart and more frequent auscultation-should be instituted where the rate rises to 160 or drops to 120 a minute. “

They also suggest that these suggestions, whilst representing minimum requirements, require time and judgement and advocate this “might be best done by a continuously recording cardiograph”.

History of the CTG. 

Cardiotocography (CTG), the simultaneous recording of uterine and fetal cardiac activity, started development more than 60 years ago to prevent still births during labour. In this it was effective. Its’ problems began when its use was extended to attempts to predict rather than diagnose fetal distress.

Antepartum cardiotocography (aCTG), known in the United States as the NST (Non-Stress Test) was pioneered by several groups simultaneously in Europe. The first report from the UK was that of Huntingford & Pendleton 1969.

In Oxford in the early 1970s new methods to control the blood pressure of pre-eclamptic women with antihypertensive drugs were developed. They had never been used in this context before. This seemed to be the way forward in coping with the problem of very early onset disease, before 34 weeks to allow delivery, after controlling the mother’s condition. 

But the perinatal mortality was appalling. Special care was very primitive and babies electively delivered at this time did badly, especially because they were growth restricted by maternal pre-eclampsia. So in the first two years of managing such women (delaying delivery for PE before 34 weeks) all the babies died: more than half were stillborn and the rest died after delivery. This was not a success. The problem was that there was no way of recognising fetal distress in utero.  However, a new electronic fetal heart rate monitor (just one) had arrived in delivery suite, for use in labour. It was borrowed, it to see if it could identify problems before Labour. And it did! So, after 2 years Oxford began to use one (more had arrived) systematically and the stillbirth rate plummeted dramatically. That is how it all began. At this time St Mary’s Hospital Paddington were ahead of Oxford.

The use of antepartum CTG over the next year was revelatory. For the first time it became possible with reasonable reliability to see impending intrauterine death in the context of severs early onset pre-eclampsia or fetal growth restriction. The impact on perinatal survival in these cases was impressive.

Descriptive evidence from other centres confirmed this substantial benefit (retrospectively by Klungsøyr et al 2012). 

Nowadays, electronic fetal heart rate monitoring is the state of the art. However, it has major problems that make the measurement of its usefulness difficult or impossible. These include unacceptable variation in interpretation between observers and the high volume of data even in one short trace that make it difficult to analyse except by computerisation. These problems are addressed by DR-CTG.

The pattern of the antepartum CTG differs as to whether the stress is chronic (long term) or acute. Thus short term variation (STV) predominates in the former, whereas various patterns of decelerations tend to be more obvious during labour.

References

Fitzgerald TB, McFarlane CN. Foetal distress and intrapartum foetal death. Br Med J. 1955 Aug 6;2(4935):358-61.

Gultekin-Zootsmann B. The history of monitoring the human fetus. J Perinat Med 1975;3:135-144

Gunn A L & WoodM C (1953) Proc. roy. Soc. Med. 46,85

Hon EH (1959) Observations on “pathologic” fetal bradycardia. AJOG. May 01, 1959;77:1084-1099. 

Huntingford PJ, Pendleton HJ.The clinical application of cardiotocography. J ObstetGynaecol Br Commonw. 1969 Jul;76(7):586-95

Klungsøyr K, Morken NH, Irgens L et al . Secular trends in the epidemiology of pre-eclampsia throughout 40 years in Norway: prevalence, risk factors and perinatal survival.  Paediatr Perinat Epidemiol. 2012 May;26(3):190-8.

Pinkerton JHM (1968) Kergaradec, Friend of Laennec and Pioneer of Foetal Auscultation.  First Published May 1, 1969 Meeting Report

https://doi.org/10.1177/003591576906200524 

Schmidt and McCartney, 1999] CTG, History.KKK  Hon 1959]

Stewart A, Kneale GW (1970) Radiation dose effects in relation to obstetric x-rays and childhood cancers. Lancet 1(7658): 1185-8