Summer 2015 ISSUE 145 Midwifery Matters 7 In my 2014 book, Dynamic Positions in Birth, I questioned the existence of the ‘fundal pacemaker’. The accepted wisdom taught in textbooks is that a fundal pacemaker initiates downward contractions of the uterus during labour. Clinical teaching has been based on this theory since the middle of the last century. Fundal dominance was outlined in the 1948 edition of Reynold’s book The Physiology of the Uterus and expanded by Caldeyro Barcia and Reynolds in 1950 (. It is still widely taught. The immediate implication of this is that the fundus will act as a battering ram, propelling the fetus towards the exit. In the light of recent advances in the measurement of contractions spreading around the uterus, it is time to revisit the theory. Biophysical data do not support the classical theory. These days medical equipment companies are funding research into recording uterine activity in the hope of finding a way to distinguish between established premature labour and threatened early labour. The main focus has been on measuring myometrial activity by electromyography, detecting the electrical activity that drives the muscle contraction of the uterus (EHG, electrohystomyography). Magnetometry has also been used and even MRI. Using the power of computers, researchers are now able to see the site of initiation and calculate the direction of contractions. They see neither a fundal pacemaker nor consistently downward contraction patterns. Karlsson et al write: “It is possible at times to observe ascendant activation patterns while for the majority of the contractions the activation patterns is descendant. In this situation, the uterine activity begins at the lower electrodes or those situated on one side and then propagates to the other electrodes. Several origins of the activity could often be observed.” Lange et al write: [the theory that pacemaker regions is disputed by] “recent EHG studies, showing seemingly random directions of propagation indicating that a contraction can originate in many different areas of the uterus. Interest in the function of the uterus as a whole organ waned with the advent of safer caesarean section. Once abnormal labour could be ‘rescued’ by surgery, there was less incentive to understand normal labour and research funding went elsewhere, primarily into pharmacology (prostaglandins and syntocinon) and technology (electronic fetal monitoring (EFM) and ultrasound). There was more clinical interest in recording labour mechanically (to gain an ‘objective’ view of the progress of labour) than there was in using the information to gain a better understanding of uterine function. The new technology of EFM was welcomed by obstetricians as it appeared to provide an objective record of the progress of labour and it is now seen to be indispensable in the management of abnormal labour and, in some countries, normal labour as well. With hindsight we now know that this was a grave mistake, apart from one study finding a decrease in neonatal seizures in babies of women whose labours were subject to EFM, all that it does is to increase the caesarean section rate (Alfirevic, Devane, Gyte, 2006). EFM tends to immobilise women which, I believe, tends to increase pain by denying women the chance of finding for themselves comfortable positions in labour. One of the principles underlying EFM came directly from the concept of fundal dominance, i.e. that contractions measured near the fundus reflected uterine activity as a whole and could be compared with the fetal heart rate to give an idea of how the fetus was coping with labour. A late deceleration was deemed to be associated with a struggling fetus whose delivery should be expedited. However, if contractions do not always emanate from the fundus, then a deceleration immediately following a contraction initiated elsewhere could be misinterpreted as ‘late’ when it actually reflects a normal response. (fig 1, graph of internal and external contractions) Anecdotal reports of babies being born in unexpectedly good condition, with high Apgar scores, following caesarean section, are manifold. Figure 1 internal and external contractions Smooth line = external tocograph Jagged line = electromyograph, total activity from 12 sensors External tocography is not a reliable measure of uterine activity, the tocograph records only two dimensions of a contraction, the line on the graph The Myth of Fundal Dominance Margaret Jowitt