Stages of Hypoxic Ischemic Encephalopathy

This page has been written, edited, and reviewed by a team of legal writers following our comprehensive editorial guidelines. This page was approved by Founding Partner, Terry Crouppen who has more than 40 years of legal experience as a personal injury attorney. Our last modified date shows when this page was last reviewed.

This page has been written, edited, and reviewed by a team of legal writers following our comprehensive editorial guidelines. This page was approved by Founding Partner, Terry Crouppen who has more than 40 years of legal experience as a personal injury attorney. Our last modified date shows when this page was last reviewed.

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Hypoxic ischemic encephalopathy, also known as HIE, is a serious condition caused by a lack of oxygenation at birth. It can lead to life-long consequences and require ongoing medical care. HIE is diagnosed based on numerous factors during and after birth. 

Brown & Crouppen is a full-service personal injury law firm. Our skilled birth injury lawyers are prepared to help you seek full and fair compensation if your child has developed HIE due to medical malpractice. Call (800) 536-4357 or reach out online to learn more in a free consultation. 

Hypoxic Ischemic Encephalopathy Diagnosis

In 1976, Harvey and Margaret Sarnat developed the Sarnat Scale, which categorizes the severity of hypoxic ischemic encephalopathy stages from mild to severe. The Sarnat HIE Scale measures a child’s overall condition by looking at certain key clinical factors, including:

  • Tone
  • Level of consciousness
  • Seizures
  • Posture
  • Moro reflex
  • Grasping
  • Sucking
  • Respiratory patterns 
  • Fontanelle findings
Based on these factors, a child may be diagnosed with stage one, two, or three HIE. 

HIE symptoms may also be gauged using the Apgar scale, which is deployed in delivery rooms to determine a newborn’s health based on a score between 0–10. A score of 7 or higher is considered normal. An Apgar score of 3 or less for more than five minutes post-birth may be a sign of HIE.

What Are the Sarnat Stages of Hypoxic Ischemic Encephalopathy?

There are three stages of HIE recognized in the Sarnat Scale: 

Stages of Hypoxic Ischemic Encephalopathy Infographic - HIE Attorneys in Missouri

HIE Stage 1 – Mild

In mild cases of HIE, infants typically show symptoms immediately after birth, which may include the following:

  • Trouble feeding
  • Fussiness
  • Decreased muscle tone
  • Short or limited deep tendon reflexes
  • Hyperalertness
  • Frequent crying
  • Trouble falling and staying asleep

Symptoms may also arise within the first 24 hours after birth, but some may occur even later. 

HIE Stage 2 – Moderate

Children who have moderate cases of HIE show somewhat more extreme symptoms, including:

  • Difficulty breathing or apnea
  • Seizures
  • An absence of the Moro reflex
  • Trouble grasping with their hands
  • Hypotonia
  • Lethargy
  • Disinterest in sucking

Appropriate medical intervention and care can improve the prognosis and lead to recovery. Monitoring and treating symptoms during the first few weeks after birth is vital.

HIE Stage 3 – Severe

Severe HIE result in far more severe symptoms, such as:

  • Irregular breathing
  • Seizures
  • Stupor
  • Coma

Symptoms in this stage are acute and profuse, lasting from hours to weeks. Seventy-five percent or more of infants with this stage of HIE develop serious disabilities. Many cases are fatal.

Treatment Options for Hypoxic Ischemic Encephalopathy

Prompt hypoxic ischemic encephalopathy treatment can significantly improve a child’s prognosis. The primary treatment in severe cases is therapeutic hypothermia, which involves cooling the brain to reduce damage from oxygen deprivation in the hope of mitigating its long-term effects. 

During cooling treatment, the infant is chilled for up to 72 hours while their vital signs are closely monitored. Once the 72 hours have passed, medical providers slowly warm the body back up for around 12 hours. 

HIE's Long-Term Impacts

The long-term consequences of HIE can vary greatly depending on the severity of the oxygen deprivation and the effectiveness of medical interventions. Potential long-term include:

  • Neurodevelopmental Delays – Children who experience HIE may develop neurological and developmental delays. This can affect cognitive abilities, motor skills, language development, and social interactions. 
  • Cerebral Palsy – HIE is a significant risk factor for cerebral palsy, a disorder that affects movement and muscle coordination. Cerebral palsy can result in muscle stiffness, weakness, tremors, and difficulties with coordination and balance.
  • Epilepsy – HIE increases the risk of developing epilepsy, a neurological disorder characterized by recurrent seizures. Seizures may vary in severity, impacting daily functioning and quality of life.
  • Behavioral and Emotional Challenges – Children who have HIE may be at an increased risk of behavioral and emotional challenges. This can include difficulties with attention, impulsivity, hyperactivity, and emotional regulation.
  • Sensory Impairments – HIE can lead to sensory impairments, such as visual or hearing loss. These impairments can further impact a child’s development and ability to interact with the environment.
  • Motor Impairments – Motor impairments are common in children with HIE and can range from mild difficulties with coordination to severe paralysis or spasticity.
  • Speech and Language Disorders – Some children with HIE may experience difficulties with speech and language development, including articulation problems, learning delays, and difficulties with comprehension and expression.
  • Secondary Medical Complications – Individuals with HIE may be at risk for secondary medical complications, such as respiratory problems, gastrointestinal issues, feeding difficulties, and susceptibility to infections.

How Common Is HIE?

HIE impacts 2–3 infants out of every 1,000 full-term births. That said, the long-term impact of HIE varies from child to child. According to one study, “40–60 percent of affected infants die by two years of age or have severe disabilities.” 

However, the prognosis for children with mild HIE is much better than for those with mild symptoms. Stage 1 HIE leads to a severe handicap in fewer than 5 percent of cases. By contrast, Stage 2 can lead to severe handicaps or death in up to 75 percent of infants. Tragically, Stage 3 leads to severe disability or death in 75 percent or more infants.

Brown & Crouppen Can Help

HIE is often preventable but may occur because of medical malpractice, including:

  • Delayed diagnosis
  • Failing to diagnose HIE
  • Failing to implement therapeutic hypothermia in a reasonable amount of time
  • Failing to perform a cesarean section within a reasonable amount of time

Our compassionate legal team understands the traumatic nature of receiving a hypoxic ischemic encephalopathy diagnosis for your baby. Our lawyers have extensive experience handling birth injury lawsuits throughout Missouri and have secured over $1 billion in settlements and verdicts for our clients. 

To better serve the needs of our community, we work on a contingency basis. This means you pay nothing unless we win your case. We are here to help you seek full and fair compensation for the negligence that caused your child’s birth injuries. Call (800) 536-4357 or reach out online to schedule your free consultation today. 


  • Allen, MSN, RN, K. A., & Brandon, PhD, RN, CCNS, FAAN, D. H. (2011, September 1). Hypoxic Ischemic Encephalopathy: Pathophysiology and Experimental Treatments. National Library of Medicine. Retrieved March 11, 2024, from
  • Child Neurology Society. (2021, May 6). Harvey Sarnat, MD – Child Neurology Society
  • Hope for HIE. (2023, September 15). What is HIE? – Hope for HIE – Hypoxic Ischemic Encephalopathy. Hope for HIE – Hypoxic Ischemic Encephalopathy.
  • Hypoxic-Ischemic Encephalopathy (HIE) Facts & Statistics. (2024, February 13). HIE Help Center.
  • Hypoxic-Ischemic encephalopathy (HIE) » Florida Neonatal Neurologic Network. (n.d.).
  • Overview of Therapeutic Hypothermia. (2012, December 14). National Library of Medicine. Retrieved March 12, 2024, from
  • Queensland Clinical Guidelines. (2021). Hypoxic ischaemic encephalopathy (HIE) (Clinical Guideline MN21.11-V11-R26). Queensland Health.
  • Zanelli, S. A., MD. (n.d.). Hypoxic-Ischemic Encephalopathy: practice essentials, background, pathophysiology


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