Impaired oxygenation (hypoxia-ischemia) to the fetal brain during labour and delivery (intrapartum) is an important cause of neurologic injury in the newborn. Determining whether neurologic injuries in affected babies may have been preventable by different intrapartum management of care begins by understanding the causal pathways to newborn neurologic injury. There are many variables to be considered in the causation analysis, including maternal factors, genetic issues, antenatal factors, intrapartum clinical data and neonatal clinical data. The subject is complex and not without controversy.
Not only has there been controversy surrounding the ‘science’ of the pathways to newborn neurologic injury, but the discourse has been tainted by bias. For lawyers representing affected newborns, a successful claim requires establishing causation on a balance of probabilities, or more likely than not. For physicians defending these substantial claims, causation is vigorously challenged.
There is a considerable body of medical literature published on the issue, some with the professed objective of establishing guidelines to better understand these causal pathways. This paper will review some of the medical literature on the subject and important publications on the matter from the American College of Obstetricians and Gynecologists. At the outset, however, the reader must keep in mind that there are two variables in the causation analysis that provide the most objective evidence of an injury occurring at or around the time of birth: a particular topography of newborn brain injury on neuroimaging; and, umbilical cord blood gas analysis demonstrating a metabolic acidosis.
 Undoubtedly this article will attract that very criticism.