Long-Term Neurodevelopmental Outcomes of Neonatal Hypoxic-Ischaemic Encephalopathy in a Nigerian Prospective Birth Cohort: Aetiology, Severity, and Modifying Factors

Neonatal hypoxic-ischaemic encephalopathy is a leading cause of cerebral palsy, intellectual disability, and epilepsy in Nigerian children, yet longitudinal data linking encephalopathy severity at birth to specific neurodevelopmental outcomes at school age are absent from the Nigerian literature. This study examines the long-term neurodevelopmental outcomes of hypoxic-ischaemic encephalopathy survivors in a prospective birth cohort recruited from neonatal units in Ibadan, Enugu, and Jos, with follow-up from birth to age seven years. A prospective cohort of 600 term neonates with confirmed HIE (300 mild-moderate, 300 severe) and 300 normoxic control neonates is enrolled. HIE is classified using Sarnat staging, and aEEG is performed in the first 24 hours. Neurodevelopmental outcome assessment at 12, 24 months, and seven years uses the Bayley Scales of Infant and Toddler Development and the NEPSY-II battery. Brain MRI at three months correlates with neurodevelopmental trajectory. Nutritional status, socioeconomic position, access to therapeutic hypothermia, and seizure management quality are examined as modifying factors using linear mixed-effects models in R. The Neuroplasticity Theory and Cumulative Developmental Risk Model inform the theoretical framework. Original contributions include the first seven-year longitudinal neurodevelopmental study following HIE in a multi-site Nigerian cohort, and a validated risk stratification model incorporating clinical and MRI predictors. Findings will guide therapeutic hypothermia roll-out prioritisation and early intervention programme design. Keywords: hypoxic-ischaemic encephalopathy, neurodevelopmental outcomes, Nigerian birth cohort, therapeutic hypothermia, neonatal neurology.