Trends and racial differences in hypoxic ischemic encephalopathy-related mortality in newborns in the United States, 2007-2022

Background: Hypoxic ischemic encephalopathy (HIE) is a significant cause of morbidity and mortality. However, the changes in HIE-related mortality and its associated racial differences, if any, have not been extensively studied. We examined the population-based temporal trends and any racial differences in the HIE-related infant mortality rate (HIE-IMR) in the United States from 2007 through 2022. Methods: This was a retrospective cross-sectional analysis of linked birth and infant death records data from the CDC WONDER from 2007-2022. We evaluated all infants born at >= 35 weeks gestational age (GA) who died within the first year of life with HIE (ICD-10 codes P91.6 and P21) as the underlying cause of death. The exposure was the year of death, and the outcomes were the changes in overall HIE-IMR and then stratified by race. HIE-IMR was calculated as per 100,000 live births. Linear regression was used for trend analysis. Results: Among 59,117,761 live births, 3998 infants with GA >= 35 weeks died from HIE (6.7 per 100,000). The overall HIE-IMR increased significantly from 5.2 to 9.6 per 100,000 (p < .001). The rate increased significantly in White (5.3 to 7.2; p < .001) and Black (5.2 to 8.1; p = .005) infants. The overall HIE-IMR was significantly higher in Black infants (7.3) than in White infants (7.2) [p = .02]. Conclusion: The HIE-IMR rate increased significantly, and the rate was higher in Black than in White infants. The drivers behind these changes require further examination in future studies.