Perinatal antecedents of moderate and severe neonatal hypoxic ischemic
encephalopathy: an Australian birth cohort study
Abstract
ABSTRACT Objective: The aim of this study was to investigate key
antecedents of moderate and severe neonatal hypoxic ischemic
encephalopathy (HIE) in a large contemporary Australian birth cohort.
Design: A retrospective cohort study of all births meeting the inclusion
criteria between 2016-2020. Setting: The Mater Mothers’ Hospital,
Brisbane, Australia. This is a quarternary perinatal center and
Australia’s largest maternity hospital. Population: All non-anomalous,
singleton liveborn infants, >35+0 weeks gestation. Methods:
Univariate and multivariate firth logistic regression were used to
account for imbalanced frequency classes. Main outcome measure: Neonatal
moderate and severe HIE. Results: Overall, 133/46041 (0.29%) infants
were diagnosed with HIE, and 56 (0.12%) were diagnosed with
moderate/severe HIE. Nulliparity, type 1 diabetes mellitus and maternal
intensive care unit admission were associated with increased odds of
moderate/severe HIE. Intrapartum risk factors included emergency
cesarean birth, emergency cesarean for non-reassuring fetal status or
failure to process, intrapartum hemorrhage, and an intrapartum sentinel
event (shoulder dystocia, cord prolapse, uterine rupture, placental
abruption). Neonatal risk factors included male sex, birth at late
preterm gestation (35+0 – 36+6 weeks), Apgar score <4 at 5
minutes, severe respiratory distress requiring ventilatory support and
severe acidosis at birth. Conclusions: This cohort study identified a
series of potentially modifiable maternal and obstetric risk factors for
HIE. Risk factors for HIE do not appear to have changed significantly
despite recent advances in obstetric care. Key words: pregnancy, fetus,
fetal distress, intrapartum hypoxia, hypoxic ischemic encephalopathy,
cerebral palsy Funding source: The authors acknowledge research support
by the Mater Foundation.