Abstract
Over the last 30 years, the caesarean section rate has reached global epidemic proportions.
This trend is driven by multiple factors, an important one of which is the use and
inconsistent interpretation of the electronic fetal monitoring (EFM) system. Despite
its introduction in the 1960s, the EFM has not definitively improved neonatal outcomes,
yet it has since significantly contributed to a seven-fold increase in the caesarean
section rate. As we attempt to reduce the caesarean rates in the developed world,
we should consider focusing on areas that have garnered little attention in the literature,
such as physician sensitization to the poor predictive power of the EFM and the research
method biases that are involved in studying the abnormal heart rate patterns—umbilical
cord pH relationship. Herein, we apply Bayes theorem to different clinical scenarios
to illustrate the poor predictive power of the EFM, as well as shed light on the principle
of protopathic bias, which affects the classification of research outcomes among studies
addressing the effects of the EFM on caesarean rates. We propose and discuss potential
solutions to the aforementioned considerations, which include the re-examination of
guidelines with which we interpret fetal heart rate patterns and the development of
noninvasive technologies that evaluate fetal pH in real time.
Keywords
fetal pH - caesarean section - Bayes theorem - protopathic bias
