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Hypoxic-ischemic encephalopathy (HIE)

Author: Judy Zhu

Hypoxic-ischemic encephalopathy (HIE) is a brain injury caused by oxygen deprivation to the brain, also commonly known as intrapartum asphyxia. Although adults can experience HIE, it is most commonly occurs as a serious birth complication as the result of an oxygen-depriving event during or around the time of birth. 40–60% of affected infants die by 2 years of age or have severe disabilities.

HIE due to fetal or neonatal asphyxia is a leading cause of death or epilepsy, developmental delay, motor impairment, neurodevelopmental delay, and cognitive impairment among infants.

Before birth

  • Decreased fetal movement

  • Severe maternal cramping (often accompanied by severe back pain)

  • Abnormal fetal heart rate

  • Abnormal contraction pattern

  • Vaginal bleeding

  • Abnormally low or high maternal weight gain

  • Maternal high blood pressure

In the neonatal period

  • Low Apgar scores at five or 10 minutes

  • Seizures

  • Difficulty feeding

  • Breathing problems

  • Hypotonia (low muscle tone)

  • Organ problems (failure, damage)

  • Acidemia (low pH in umbilical cord blood gas tests)

  • Abnormal response to light

  • State of abnormal consciousness (hyperalert or lethargic)

  • Coma


During infancy and early childhood

  • Impaired motor function

  • Delayed developmental milestones (behavioral signs of the growth and development of babies and children)

  • Seizure disorder

  • Delayed growth

  • Hearing and visual impairments

  • Risk factors

  • Acute maternal hypotension (low blood pressure)

  • Blood containing less oxygen due to poorly functioning lungs

  • Impaired blood flow to the brain during birth

  • Cardiac complications

  • Injury from cephalopelvic disproportion (when a baby's head is too large to fit through the mother's pelvis)

  • Intrapartum hemorrhage

  • Prolapsed cord

  • Placental abruption

  • Pressure to the cranium (bones that form the head) that changes it shape, resulting in bleeding or decreased blood flow

  • Stress of labor and delivery

  • Uterine rupture

  • Fetal stroke

Once HIE is suspected, neuroimaging techniques, especially MRIs, are performed to aid diagnosis. New techniques, including diffusion-weighted imaging and MR spectroscopy may also be used.

Asphyxia typically causes permanent damage, which sometimes continues to progress even after the asphyxia has been relieved. Therefore, treatments for HIE focuses on helping the child adapt to symptoms that result from the brain injury. To prevent further damage the child can be medically monitored to:

  • Maintain normal blood glucose

  • Maintain normal blood pressure

  • Prevent or control seizures

  • Prevent or minimize cerebral edema (swelling of the brain)

Newborn Infant Nurs Rev. 2011 Sep 1; 11(3): 125–133. doi: 10.1053/j.nainr.2011.07.004

“Hypoxic-Ischemic Encephalopathy, or HIE, Also Known as Intrapartum Asphyxia.” Cerebralpalsy.Org,

“Hypoxic-Ischemic Encephalopathy (HIE): Signs and Symptoms.” HIE Help Center, 18 Nov. 2019,


“What Is Hypoxic-Ischemic Encephalopathy (HIE)?” HIE Help Center, 17 Aug. 2020,
Jaisankar, PremKumar, and Rajeswaran Rangasami. “MR Imaging and MR Diffusion 

Tensor Imaging in Mega Corpus Callosum.” Neurology India, vol. 63, no. 6, 2015, p. 997. Crossref, doi:10.4103/0028-3886.170112.

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