Maternal Social Determinants of Health and Risk of Perinatal Hypoxic-Ischemic Encephalopathy.

Importance: Perinatal hypoxic-ischemic encephalopathy (HIE) is an important cause of mortality and long-term morbidity. The association between maternal social determinants of health (SDOH) and perinatal HIE has not been established. Objective: To examine the association of maternal race, ethnicity, and other SDOH with perinatal HIE. Design, Setting, and Participants: This cross-sectional study of a birth cohort of insured maternal-neonatal dyads with births between January 1, 2012, and July 31, 2019, examined neonates born at 35 weeks' gestation or later at 15 Kaiser Permanente Northern California hospitals. Data were analyzed from May 12 to August 31, 2024. Exposures: Maternal race and ethnicity were classified by self-report. Other measures of SDOH included the neighborhood deprivation index (NDI), a marker of neighborhood-level socioeconomic disadvantage, and being publicly insured. Main Outcomes and Measures: The primary outcome was perinatal HIE, defined as the presence of perinatal acidosis (cord gas pH <7 or base deficit ≥10 mmol/L, or base deficit ≥10 mmol/L on first infant blood gas sample obtained before 2 hours of age), and neonatal encephalopathy, confirmed by medical record review. Results: Of 290 535 newborns, 51.1% (148 158) were male, and the mean gestational age was 39 weeks; 25.8% (n = 75 011) were Hispanic, 24.6% (n = 71 366) were non-Hispanic Asian or Pacific Islander, 6.4% (n = 18 602) were non-Hispanic Black, 4.2% (n = 12 214) were non-Hispanic multiracial, and 37.6% (n = 109 147) were non-Hispanic White. Maternal race and ethnicity data were missing for 1.4% of newborns (n = 4195). The prevalence of perinatal HIE was higher among newborns of non-Hispanic Asian (0.2%; risk ratio [RR], 1.38 [95% CI, 1.06-1.80]), non-Hispanic Black (0.2%; RR, 1.66 [95% CI, 1.15-2.14]), and non-Hispanic White mothers (0.2%; RR, 1.54 [95% CI, 1.21-1.95]) than newborns of Hispanic mothers (0.1%). Black and Hispanic mothers were more likely to reside in neighborhoods with greater socioeconomic disadvantage and to be publicly insured. After adjustment for NDI, public insurance, and clinical characteristics, neonates of Hispanic mothers had 25% lower odds of HIE compared with neonates of non-Hispanic White mothers (odds ratio, 0.75 [95% CI, 0.60-0.95]; P = .02). The highest tertile of NDI, indicating higher neighborhood deprivation, was independently associated with decreased odds of HIE compared with the middle tertile (odds ratio, 0.78 [95% CI, 0.62-0.98]; P = .03). Conclusions and Relevance: These findings suggest that there was a lower prevalence of perinatal HIE among newborns of Hispanic mothers and among newborns of mothers who resided in the most socioeconomically disadvantaged neighborhoods. Determining the root causes for the lower risk of perinatal HIE among specific subgroups may inform the development of targeted HIE prevention policies.