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Hypoxic ischemic encephalopathy (HIE)—sometimes called perinatal asphyxia or intrapartum asphyxia—is a life-threatening condition that occurs in babies during or shortly after birth.

Many babies experience a mild state of hypoxia (oxygen deprivation) after birth, and need resuscitation or assistance breathing. Most are fine, continue getting oxygen from the placenta during birth, and suffer no serious side effects.

When the oxygen deprivation is longer lasting or occurs under other circumstances that endanger a baby's life, the baby can suffer lifelong consequences ranging from minor learning impairments to global deficits in functioning.

What is Hypoxic Ischemic Encephalopathy?

HIE damages the brain in two distinct phases. First, the brain is deprived of oxygen for a period of time, damaging brain cells. If the oxygen deprivation is severe enough or lasts long enough, portions of the brain may die, impeding functions associated with those brain regions.

The second phase of HIE begins when the brain regains oxygen. As blood and oxygen flow to damaged areas of the brain, those regions may release toxins that further damage the brain. This is known as a reperfusion injury. Because of the additional dangers posed by reperfusion injury, doctors often proceed with caution when giving oxygen treatments to babies, and even babies who only suffered oxygen deprivation for a short period of time may need to be monitored.

Not all babies with HIE suffer lasting consequences. Indeed, if the HIE is mild or moderate, the baby might be fine after receiving oxygen. Other babies continue to display behavioral abnormalities for the first 24 hours or so, then are fine. It's babies who continue to display symptoms for a day or longer who are at the greatest risk of long-term side effects.

What Causes Hypoxic Ischemic Encephalopathy?

Full-term babies who experience normal vaginal deliveries and who have healthy mothers are unlikely to suffer from HIE. The proximate cause of HIE is oxygen deprivation, of course, but a number of birth-related accidents and trauma can increase the risk of oxygen deprivation. Those include:

  • Placenta issues, including placental insufficiency or ruptured placenta. 
  • Uterine rupture. 
  • Umbilical cord knots; note that an umbilical cord wrapped around the neck rarely is sufficient to induce HIE.
  • Cord compression. 
  • Trauma during delivery, such as the baby getting stuck in the birth canal with the cord wrapped around its neck for an extended period of time. 
  • Ruptured aneurysm. 
  • Cord prolapse. 
  • Maternal hemorrhage, and any other maternal conditions that result in low blood pressure. 
  • Extremely early preterm birth. 
  • Extremely clogged lungs; it's common for babies to be born with some fluid in their nose and lungs. 

What Are the Risk Factors for Hypoxic Ischemic Encephalopathy?

Full-term babies are extremely unlikely to suffer from HIE, so carrying a pregnancy as long as is safe for mother and baby is one of the best ways to prevent HIE. Risk factors for HIE do not mean a baby will suffer from hypoxia, or even that hypoxia is likely. They merely alert the medical team that extra precautions may be necessary to prevent an oxygen deprivation event. Some risk factors for HIE include:

  • Vascular disease in the mother.
  • Gestational diabetes, particularly when it necessitates an early birth.
  • Premature birth; the earlier the birth, the greater the danger will be to the baby.
  • Placenta abnormalities.
  • Infections and congenital defects in the baby.
  • Maternal drug and alcohol abuse.
  • Pre-eclampsia or HELLP syndrome.
  • Fetal or maternal anemia.
  • Malformed lungs.

What Are the Symptoms of Hypoxic Ischemic Encephalopathy?

Immediately after oxygen deprivation, babies show a number of telltale signs. Those include:

  • Low heart rate.
  • Poor muscle tone; the limbs may be limp.
  • Blue or white coloring, or not breathing at birth.
  • Meconium-stained amniotic fluid.
  • Born breathing weakly, intermittently, or not at all.
  • Depressed or absent newborn reflexes.
  • Inability to nurse.
  • Changes in eye movement; eye movements may be poorly coordinated or shaky.
  • Dilated or unmoving pupils.
  • Low or irregular blood pressure.
  • Unresponsive at birth.

The long-term effects of HIE are heavily dependent on the severity and length of oxygen deprivation. Some babies make speedy recoveries, while others suffer an array of health issues. Some possible outcomes include:

  • Developmental delays such as autism.
  • Learning disorders, such as dyslexia and ADHD.
  • Motor difficulties.
  • Difficulties learning language.
  • Mental health problems.
  • Intellectual disabilities.
  • Chronic infections.
  • Allergies and other immune disorders.
  • Seizures and epilepsy.
  • Cerebral palsy.
  • Behavioral problems, including impulse control issues and behavior that seems immature for your child's age.

How Is Hypoxic Ischemic Encephalopathy Diagnosed?

Diagnosing the specific cause of symptoms is less important at first than treating the symptoms. In the immediate aftermath of the birth, the doctor or midwife will focus on stabilizing the baby and getting him or her to breathe. Once the baby is reasonably stable and no longer in immediate danger, the medical team may perform a number of tests to rule out other disorders. Those include:

  • MRI scans.
  • Echocardiograms to test the heart.
  • CT scan.
  • Ultrasounds.
  • Reflex tests.
  • Electrocardiogram.

How is Hypoxic Ischemic Encephalopathy Treated?

Babies born with hypoxia may need to be placed on ventilators or in incubators to reduce their risk of other serious consequences. As with most other health issues in babies, nursing can help stimulate the brain and heart while promoting healing, even if the baby must receive breast milk through a tube or donor breast milk.

After a baby is stabilized, treatment depends on the severity of symptoms. Some babies will need no treatment at all, but most will be monitored for developmental delays and subsequent breathing problems. Over time, your child's pediatrician may construct a plan designed to offset any symptoms she experiences. Some common treatments include:

  • Physical therapy.
  • Family counseling to help you better support your child.
  • Exercise and play therapy.
  • Speech therapy.
  • Psychotherapy.
  • Tutoring and skills training.
  • Medication to address behavioral or cognitive issues.
  • Lifestyle recommendations, such as following a specific diet or encouraging your child to read each day.
  • Parental training.

Because symptoms may take years to fully appear, it's important to tell all of your child's medical providers about his history of HIE, since otherwise he might be diagnosed with or treated for the wrong condition.

Further Reading:

Radiopaedia.org

University of Florida