Adverse long-term outcomes following seizures in non-asphyxiated term infants: A population-based cohort study

While birth asphyxia is a well-established cause of neonatal seizures associated with adverse outcome, less is known about outcomes after seizures in non-asphyxiated infants. We investigated adverse outcomes following neonatal seizures in infants born vigorous and without evidence of asphyxia.

Swedish national cohort (2009-2015) including 656,088 live-born term vigorous infants. The exposure was a diagnosis of neonatal seizure. A combined adverse outcome included any diagnosis of cerebral palsy, epilepsy, intellectual and developmental disability, or death. Hazard ratios (HR) with 95% confidence intervals (CI) were calculated.

470 infants were diagnosed with seizures, and 299 (64%) had EEG-verified seizures. Among those with the combined adverse outcome, 75% were diagnosed the first year, corresponding to an incidence of 178 per 1000 of all infants and 224 per 1000 among EEG-verified cases. The one-year incidence rates were 220 per 1000 child years for all, and 283 per 1000 child years among those EEG-verified compared to 2.3 per 1000 child years without seizures. The HR for all seizures within 1 year was 95 (77-120), and for EEG-verified seizures 120 (96-160).

This study demonstrates a strong association between neonatal seizures and adverse long-term outcome in vigorous term infants without asphyxia.

Term infants who were vigorous and non-asphyxiated at birth but later developed neonatal seizures faced a significant elevated risk of adverse outcomes, including death, cerebral palsy, epilepsy, intellectual and developmental disabilities. Among these adverse outcomes epilepsy was the most frequent and was predominantly diagnosed during the first year of life. Population-based studies utilizing national health and quality registers can greatly enhance our understanding of long-term outcomes following neonatal seizures.