Epidemiology, Pathophysiology, and Pathogenesis of Fetal and Neonatal Brain Injury and Encephalopathy

Neonatal encephalopathy (NE) is a clinical disorder of brain function that arises from various conditions impacting the central nervous system around the time of birth. Key symptoms include altered consciousness, respiratory depression, cranial nerve dysfunction, tone abnormalities, and seizures. The incidence of NE is estimated at 3 per 1,000 live births, with hypoxic–ischemic encephalopathy (HIE) accounting for approximately 1–1.5 per 1,000 live term births. Recent debates have centered around the definition and diagnosis of HIE, particularly concerning cerebral blood flow and oxygen delivery at birth. Identifying infants at high risk for evolving HIE is crucial, as therapeutic hypothermia, the only known treatment that can improve neurological outcomes, needs to be administered within 6 hours of birth. This chapter focuses on HIE as a distinct cause of NE, detailing its diagnosis and management, and discusses other conditions that may present with encephalopathy at different times post-delivery.