Hypoxic Ischemic Encephalopathy
Hypoxic-ischemic encephalopathy, also called HIE, is a type of brain injury that occurs when an infant's brain does not get enough oxygen and/or blood flow, typically before, during, or just after birth. When oxygen and blood circulation are cut off even for minutes, it can trigger brain cell death and cause permanent damage or even death. HIE affects around 1 to 3 infants per every 1,000 births.
What Is Hypoxic-Ischemic Encephalopathy (HIE)?
Hypoxic-ischemic encephalopathy occurs when the brain does not get enough blood and oxygen. This can cause permanent brain damage, disabilities, and even death. Between 15 and 20% of infants with HIE die by the age of 2, and 25% who survive will have severe permanent disabilities, including:
- Mental retardation
- Visual motor or visual perceptive dysfunction
- Increased hyperactivity
- Cerebral palsy
- Epilepsy
"Hypoxic" means low levels of oxygen. "Ischemic" refers to restricted blood flow to the brain, and "Encephalopathy" refers to the damage or disease in the brain. Doctors and healthcare providers may also refer to hypoxic-ischemic encephalopathy as:
- Perinatal hypoxia
- Neonatal encephalopathy
- Birth asphyxia
How Common Is HIE?
In high-income countries (like the U.S.), HIE affects about 1-3 infants for every 1,000 births, equal to around 10,000 newborns each year. Although the condition is rare, it can lead to lifelong disabilities or even death in severe cases, which is why early intervention and care are critical.
What Causes HIE?
Hypoxic-ischemic encephalopathy can be caused by many conditions that interrupt oxygen or blood supply to the baby's brain. Common causes during each stage may include:
During Pregnancy
- Maternal drug or alcohol abuse
- Maternal diabetes
- Preeclampsia (high blood pressure)
- Vascular disease
- Advanced maternal age (over 35)
- Uterine rupture (tearing of uterus' muscular wall)
- Fetal anemia (low red blood cell count)
- Fetal lung malformation (lesions)
- Placenta separating from the wall of the uterus
During Labor and Delivery
- Prolonged labor
- Delayed intervention (C-section)
- Failure to monitor fetal distress (such as heartbeat)
- Low oxygen in the mother (hypotension)
- Umbilical cord prolapse or compression
- Abnormal fetal positions or breech birth
- Shoulder dystocia (shoulder stuck behind mother's pelvis)
- Fetal stroke
After Birth
- Trauma to the brain or skull
- Heart disease
- Lung disease
- Low blood pressure
- Infection (meningitis or sepsis)
- Hypoglycemia or hyperglycemia
- Respiratory failure
HIE can also be caused by medical negligence, such as when a doctor fails to notice preeclampsia (high blood pressure), or delays a medically necessary C-section.
What Are the Symptoms of HIE?
HIE ranges from mild to severe, so symptoms can vary widely. Some early signs in newborns include:
- Weak or irregular breathing
- Irregular heartbeat
- Low or abnormal muscle tone (too floppy or too stiff)
- Difficulty feeding or weak sucking
- Poor reflexes
- Weak cry
- Seizures or abnormal movements
- Pale, bluish skin or lips (cyanosis)
- Dilated pupils
- Unusual drowsiness
What Are the Severity Levels of HIE?
Stage 1 - Mild: HIE at this stage usually goes away on its own after a few days. Symptoms may include hyper-alertness, muscle stiffness, or floppiness. Other behavioral symptoms may involve irritability, excessive crying, poor feeding, or unusual drowsiness.
Stage 2 - Moderate: Infants with moderate HIE may show symptoms such as seizures, lethargy, weak sucking and grasping, limited reflexes and may experience apnea. Recovery for level 2 HIE is generally recoverable within a few weeks. However, outcomes can vary, and some may sustain permanent symptoms.
Stage 3 - Severe: Severe HIE can involve heart rate and breathing irregularities, coma, stupor, and hypotonia. Other symptoms include dilated pupils, limited eye tracking, and a general inability to swallow, suck, and grasp.
How Is HIE Diagnosed?
HIE is diagnosed using a variety of tests. Common tests your doctor may order for diagnosis include:
- Magnetic Resonance Imaging (MRI): An MRI is often performed within the first days or weeks of life to identify areas of the brain affected.
- Ultrasound: Ultrasounds create pictures of the baby's brain to identify damaged tissue caused by swelling or bleeding.
- Electroencephalogram (EEG): An EEG can be performed on the first day of life and scan electrical activity in the infant's brain. This test helps identify if any seizures have occurred and helps detect HIE.
- Blood tests and umbilical cord blood gas analysis: Umbilical cord blood tests assess oxygen and acid/base imbalances at birth, which can indicate potential signs of HIE.
- Computerized tomography (CT) scan: Images of the skull are taken by X-rays to create a 3-D visualization of the baby's brain.
- Lumbar puncture: Collects cerebrospinal fluid from the lower back to determine if any damage to the brain has occurred.
What Are the Effects of HIE?
Effects of HIE can be severe and result in permanent, lifelong health complications. Some effects include:
- Developmental delays: HIE can slow a child’s progress across key milestones like sitting, speaking, and social interaction. Some delays may improve with early therapy, while others may continue into childhood.
- Cerebral palsy: Moderate to severe HIE is a leading cause of cerebral palsy due to injury in the brain’s motor control areas. This can affect muscle tone, posture, and movement throughout life.
- Cognitive dysfunction: Damage from HIE may impact memory, problem-solving, and processing speed as a child grows. These challenges often become more noticeable when academic demands increase.
- Disability: Some children develop physical, intellectual, or sensory disabilities that affect their daily independence. The level of disability varies depending on the severity and location of the brain injury.
- Epilepsy: HIE is one of the most common causes of neonatal and childhood seizure disorders, with nearly half a million children in the U.S. who suffer from epilepsy. Some children experience seizures early on, while others develop epilepsy later in life.
- Vision loss: Injury to visual processing areas of the brain can lead to partial or complete vision impairment. Tunnel vision or strabismus, where the eyes are misaligned and point in different directions, affects tracking, depth perception, and visual-motor coordination.
- Hearing loss: If the auditory pathways or brainstem structures are affected, a child may develop hearing difficulties or suffer permanent hearing loss. Early screening and interventions such as cochlear implants can help improve communication outcomes.
- Organ damage or failure: Oxygen deprivation can also harm the heart, lungs, kidneys, or liver. This can create life-threatening complications, especially in the early newborn period. Of infants who survive severe HIE, over 50% will have complications involving the heart, lungs, renal system, and liver.
- Behavioral, attention, and learning problems: Some children with HIE develop difficulties with focus, emotional regulation, or school performance. These issues may not appear until preschool or elementary years.
- Motor skill delays: HIE often interferes with fine and gross motor development, such as grasping objects, crawling, or walking. These challenges may require long-term physical and occupational therapy support.
- Death or severe impairment: In the most severe cases, HIE can lead to fatal complications or serious lifelong impairments. Rapid medical intervention and early support are critical for improved long-term outlook.
What Is the Life Expectancy of a Child with HIE?
Because hypoxic-ischemic encephalopathy varies so much in severity, so does prognosis. Studies suggest that when HIE is mild to moderate and treated promptly, many children go on to live normal lives with minimal sustained damage.
However, in more severe cases where treatment is delayed, the risk of shortened lifespan is much higher. Research shows that an estimated 20-50% of infants with severe HIE may not survive the first years during the neonatal period.
In some severe cases, HIE can cause death within hours or a few days. Others who survive may face lifelong challenges such as cerebral palsy, cognitive impairment, or epilepsy. Early medical intervention, ongoing therapy, and caregiver support is important to ensure the best possible outcomes.
How Is HIE Treated?
Treating HIE is a race against time. Outcomes will depend heavily on how quickly intervention begins, how severe the injury is, and how well ongoing care is coordinated across a child's early development.
Treatment for HIE typically falls into three stages:
- Immediate neonatal treatment
- Stabilization and acute hospital care
- Long-term rehabilitation and neurodevelopmental support
Therapeutic Hypothermia (Brain Cooling)
Therapeutic hypothermia is the gold-standard treatment for moderate to severe HIE in newborns. This treatment involves lowering a baby's body temperature to about 92.3°F for 72 hours. This is shown to slow brain cell damage, reduce inflammation, and limit the spread of the brain injury.
After initial treatment, doctors will rewarm the baby's core temperature back to normal levels gradually. Therapeutic hypothermia must begin within the first 6 hours of life to be effective.
During the recovery and resting phase, the baby may be given medicine, and the medical team may perform further tests to monitor brain health to evaluate if the treatment is working properly.
Neonatal Intensive Care Unit (NICU) Support
Most babies with HIE receive care in a neonatal intensive care unit (NICU) where doctors will focus on stabilizing vital systems and preventing further injury. Other methods of treatment often include:
- Respiratory support (oxygen or mechanical ventilation), such as extracorporeal membrane oxygenation
- Blood pressure stabilization
- Temperature monitoring and fluid regulation
- Infection control and organ function monitoring (heart and kidneys)
Medications
Alongside brain cooling, doctors may use medications and drugs to help:
- Control brain swelling
- Support blood flow and oxygen delivery
- Treat infections
- Manage organ dysfunction
Early Developmental Therapies
Once the baby survives the acute stage, the focus shifts to long-term neurological development. Common early interventions — especially if the child suffers from co-occurring disorders such as cerebral palsy, include:
- Physical therapy to improve muscle tone, posture, and gross motor skills
- Occupational therapy to support hand use, feeding, and daily function
- Speech and feeding therapy for swallowing safety and communication skills
HIE and Cerebral Palsy
HIE is one of the leading causes of cerebral palsy. Oxygen deprivation may damage the areas of the brain responsible for movement and muscle control. When the motor cortex, basal ganglia, or white matter tracts are injured, the brain loses its ability to regulate muscle tone, coordination, and posture.
For children with CP who develop long-term impairments caused by HIE, there are options for treatment such as:
- Mobility aids (walkers, wheelchairs, orthotics)
- Assistive devices (AAC tools and technology to improve daily life)
- Vision and hearing support systems (cochlear implants)
Note: Not every baby with HIE develops cerebral palsy, but the risk significantly increases in moderate to severe cases, especially if treatment like therapeutic hypothermia is delayed or missed.
Can HIE Be Caused by Medical Malpractice?
Oxygen deprivation or restricted blood supply that results in HIE is often linked to medical malpractice. The most common medical mistakes that can lead to infant HIE are:
- Failure to perform a medically necessary C-section
- Premature separation of the placenta from the uterus
- Failure to identify maternal infections
- Improper use of delivery tools such as vacuum extractors or forceps
- Failure to monitor fetal distress
HIE and Cerebral Palsy Resources and Support
If your child has cerebral palsy as a result of HIE, there are many support options available. Cerebral Palsy Hub has resources to support families and their children affected by CP and other birth injuries here:
Hypoxic Ischemic Encephalopathy FAQs
Written and Medically Reviewed by:
Cerebral Palsy Hub Team
Cerebral Palsy Hub was founded to help support children and their families with cerebral palsy and to create a safe space for those affected. We strive to provide the most accurate, up-to-date information, and tools to help give your child the life they deserve.
Last Updated: November 28, 2025
