Hearing impairment after asphyxia and neonatal encephalopathy: a Norwegian population-based study

Abstract

The purpose of this study is to evaluate the association between perinatal asphyxia, neonatal encephalopathy, and childhood hearing impairment. This is a population-based study including all Norwegian infants born≥36 weeks gestation between 1999 and 2014 and alive at 2 years (n=866,232). Data was linked from fve national health registries with follow-up through 2019. Perinatal asphyxia was defned as need for neonatal intensive care unit (NICU) admission and an Apgar 5-min score of 4–6 (moderate) or 0–3 (severe). We coined infants with seizures and an Apgar 5-min score<7 as neonatal encephalopathy with seizures. Infants who received therapeutic hypothermia were considered to have moderate-severe hypoxic-ischemic encephalopathy (HIE). The reference group for comparisons were non-admitted infants with Apgar 5-min score≥7. We used logistic regression models and present data as adjusted odds ratios (aORs) with 95% confdence intervals (CI). The aOR for hearing impairment was increased in all infants admitted to NICU: moderate asphyxia aOR 2.2 (95% CI 1.7–2.9), severe asphyxia aOR 5.2 (95% CI 3.6–7.5), neonatal encephalopathy with seizures aOR 7.0 (95% CI 2.6–19.0), and moderate-severe HIE aOR 10.7 (95% CI 5.3–22.0). However, non-admitted infants with Apgar 5-min scores<7 did not have increased OR of hearing impairment. The aOR for hearing impairment for individual Apgar 5-min scores in NICU infants increased with decreasing Apgar scores and was 13.6 (95% CI 5.9–31.3) when the score was 0. Conclusions: An Apgar 5-min score<7 in combination with NICU admission is an independent risk factor for hearing impairment. Children with moderate-severe HIE had the highest risk for hearing impairment.