Oxygen Loss at Birth: What is HIE?

Before your baby is born, their brain requires a constant flow of oxygen to develop and function normally. If you experience certain conditions or complications during pregnancy or labor, the flow of blood and oxygen to your baby may slow or stop, resulting in a condition known as HIE (hypoxic-ischemic encephalopathy).

HIE occurs when the brain is injured due to a lack of oxygen, explains Danielle Guez Barber, MD, PhD, an attending physician in the neurology division at Children’s Hospital of Philadelphia. Barber specializes in perinatal brain injuries, including HIE. The condition is usually—but not always—diagnosed at birth or in the days after delivery. In the U.S., about 3 in every 2,000 babies are born with HIE, according to the National Institutes of Health. Each child is different, and the range of prognoses varies a lot, from normal outcomes to severe neurological and cognitive disabilities.

Here’s what you need to know about HIE—from its causes and symptoms, to how it’s diagnosed and treated, and how you can support your child.

Causes of HIE

During pregnancy, typical conditions that can lead to HIE include:

  • Placental abruption. The placenta provides oxygen to your baby during pregnancy via the umbilical cord. If it separates from the wall of the uterus, your baby no longer gets a steady supply of oxygen.
  • High or low blood pressure. Blood pressure conditions, such as preeclampsia (high blood pressure during pregnancy), reduce the placental blood flow to your baby.

HIE can also happen during labor. Factors that cause or increase the risk of HIE include:

  • Umbilical cord issues. The umbilical cord can become tangled or tear, or it can drop out before your baby. This can slow or stop blood flow to your baby.
  • Other delivery complications. These include placenta previa (the placenta blocks the cervix), uterine rupture (the uterus breaks open), or poor positioning that prolongs delivery (like if your baby’s shoulder gets blocked).
  • Pregnancy complications. Gestational diabetes and preeclampsia increase the risk of HIE, because they can damage the placenta. “These conditions decrease the baby’s reserve, making it harder for them to tolerate the stress of birth,” says Barber.
  • Other factors. Factors such as low birth weight, amniotic fluid contamination, very preterm birth, physical trauma to the brain or skull, and anemia in the baby have been linked to an increased risk of HIE.

In very rare cases, HIE can be caused due to medical negligence during pregnancy or delivery. For example, if a baby was born via emergency C-section due to delivery complications, there are occasional cases where doctors may have been able to prevent HIE, notes the Hope for HIE website.

However, Barber stresses that in most cases of HIE, there’s nothing a mother or a doctor could have done differently. “This is something where parents often have a lot of guilt. They go back and second-guess and wonder, ‘If I had spoken up earlier, could this have led to a different outcome?’ And almost always, the answer is no,” she says. “Even with good obstetric care and good perinatal care, that’s unfortunately what happens.”

What are the signs of HIE during pregnancy?

Doctors don’t always know that HIE is happening when it starts during pregnancy. Some signs, such as trauma to the mother’s abdomen or vaginal bleeding, immediately raise a red flag. “Sometimes it can present more subtly, with decreased fetal movement,” says Barber—i.e., a mother notices a decreased kick count.

Obstetrician performing an ultrasound on the belly of a pregnant woman
Credit: iStock | gorodenkoff

For example, at 37 weeks pregnant, Betsy Pilon noticed that her baby, Max, had stopped moving. When tests revealed Max was in distress, he was delivered by emergency C-section. An MRI revealed brain injury, confirming his diagnosis of HIE—but doctors couldn’t give the Pilons a clear idea of his prognosis. “The neurologist and neonatologist told us to wait and see,” says Pilon. “HIE is a catalyst diagnosis. There’s the initial impact, and then the potential subsequent diagnoses.”

When Max was 3 months old, vision issues became apparent. At 6 months, he began missing some developmental milestones, and at 9 months, he was diagnosed with cerebral palsy. At 8, he began having seizures at night.

When Max was a baby, Pilon found community in a small Facebook group—now a foundation called Hope for HIE—that supports more than 9,000 families globally. She is currently the executive director.

Signs of HIE after birth

Doctors perform routine tests on all babies after birth, in part to catch conditions like HIE. During labor and after a complicated labor, they may monitor your baby’s heart.

All babies receive an Apgar score—which assesses their color, muscle tone, breathing, and activity, among other measures—at 1, 5, and sometimes 10 and 20 minutes after birth. This simple assessment “is a very quick way to get a sense of how the baby is doing,” Barber says. A low first Apgar score happens frequently. Doctors become concerned if your baby continues to need a lot of stimulation and respiratory support by 5 minutes, she adds.

In the hours after birth, the healthcare team will monitor your baby for signs of HIE. These include:

  • Floppy or low muscle tone or tense muscles
  • Fatigue
  • Irritability
  • Difficulty feeding
  • Weak cry
  • Play blue-gray skin tone

Severe signs include:

  • Seizures
  • No response to touch or sound
  • Loss of consciousness
  • Abnormal breathing
  • Abnormal heartbeat
  • Poor reflexes

If doctors have a reason to suspect HIE, they’ll perform additional tests. These often include testing the cord blood, to check if the pH is lower than normal, as well as taking a sample of the placenta, to look for abnormalities. A neonatologist will usually use the outcomes of these tests to diagnose HIE. Your baby’s brain activity may also be monitored with an EEG (electroencephalogram). An MRI (magnetic resonance imaging) can also help identify signs of brain damage.

How is HIE treated?

Infant in the hospital undergoing neonatal cooling, shown with a cooling cap and cooling blanket
Credit: University College London

Therapeutic hypothermia is one treatment option for HIE. Research suggests it may help minimize disability if it’s started within six hours of birth. Your baby’s body will be cooled to 93 to 95 degrees Fahrenheit for about three days using a cooling blanket or cap, then gradually rewarmed. It isn’t used on all babies: Studies show it isn’t helpful (and maybe even harmful) for babies born before 36 weeks, says Barber. Doctors may give your child anti-seizure medication to treat seizures that can occur with HIE.

Of course, doctors also employ a variety of other techniques to treat your child. For example, “providers will use general neuroprotective strategies to protect the baby and brain from secondary injury. This includes maintaining the correct blood pressure, monitoring electrolytes, treating infections, and helping with breathing—including sometimes needing a breathing tube and ventilator,” says Craig A. Press, MD, PHD, pediatric neurologist and medical director of the neuroscience unit at Children’s Hospital of Philadelphia.

When your child leaves the hospital, their treatment team will recommend services as needed. Examples may include physical therapy, occupational therapy, speech therapy, feeding and swallowing therapy, and vision therapy. Depending on your state, your child may be systematically referred to early intervention services. (Not all states do this.) Barber adds that starting these therapies as early as possible helps to improve outcomes.

Medication, such as anti-seizure medication, may also be part of your child’s treatment.  

Interactions with caregivers can have an important impact on your child’s development. “When a child grows up in an environment where there’s a lot of attention and resources to optimizing their development, that can make a big difference,” says Barber.

For example, lots of sensory stimulation—holding, rocking, massaging—can improve your baby’s motor control. “You have to know how to feel your body before you can learn how to control movement in an organized way,” says Barber. Exposure to as much language as possible can improve cognitive function. “Reading and talking develop the brain in different ways, and babies need as much as possible of both,” says Barber.

Is HIE sometimes missed at birth?

In most cases, HIE is caught and treated at birth. “HIE can typically be diagnosed with high confidence at five to seven days after birth for the vast majority of patients,” says Pilon. But doctors don’t always suspect HIE, even in moderate and severe cases. “Often if it’s missed, it’s because the baby looked relatively well in the first few hours of life,” says Barber. “Then perhaps at 12 hours to 20 hours of life, they may start to have seizures, and it’s too late to start cooling.”

Rarely, a medical team might miss HIE in the days after birth. “We might find things later as the child is growing up. It’s less common now, but it still happens,” says Barber. For example, your child may have delayed milestones, such as walking or talking, or they might start having seizures. If this happens, the pediatrician may refer your child to a neurologist for evaluation.

A neurologist will take your child’s health history, do physical exams, and may order additional tests. Based on these evaluations, they may diagnose HIE, which was probably due to a problem that occurred “either before or around the time of birth,” says Barber.

The neurologist may also order genetic tests. “When families come to us with a child who has delays with an unknown cause and wondering if it’s HIE, the first thing we ask is if they’ve had genetic testing,” says Pilon. Genetic testing could point to rare diseases that are not due to HIE.

What is the prognosis for children with HIE?

HIE prognoses vary widely, says Barber. Your child’s long-term outcome depends on many factors, including whether you had pregnancy and/or delivery complications, gestational age at birth, if and how much resuscitation was needed at birth, whether they received therapeutic hypothermia and the environment in which they grew up. Generally speaking, the results of the tests performed after birth will help the doctors in predicting your child’s prognosis.

If your child is diagnosed with HIE, regular neurologic exams will track your child’s progress, and the doctor will likely ask you to record the frequency and severity of symptoms, such as seizures, which may appear years later. In general, doctors monitor four areas of your baby’s development:

  • Motor impairment: HIE can lead to cerebral palsy (CP), a motor impairment caused by an early-life brain injury. While some kids require a wheelchair, others have mild symptoms, says Barber.
  • Seizures: Brain injury early in life increases the risk of developing seizures later on. Babies with HIE may first have a cluster of seizures in the first hours and days after birth. “A baby may go on to never have another seizure or may have seizures in a few months or years,” says Dr. Barber. If seizures happen later, a common age is around 8 to 10 years old.
  • Vision impairment: When a vision problem stems from the brain and not the eyes, it’s known as cortical visual impairment (CVI). Kids may have difficulties with visual scanning—picking out a single item among many others, quickly reading text, or seeing numbers aligned in a column. When they start school, some struggle to read or understand math problems. Simple visual aids (like larger fonts or grids) can help.
  • Intellectual, cognitive, and behavioral function: When kids reach school age, they may struggle with learning and behavioral problems. “We keep a close eye on those domains, so that if there is a problem, we can get the child appropriate support as early as possible,” says Barber.

If most of these factors are reassuring, “then there can be a really good prognosis,” says Barber. If some pieces are concerning, “I consider a more impaired prognosis,” she adds.

Research suggests that 25 to 60 percent of babies with HIE have long-term neurological conditions (like CP or epilepsy) or issues with cognitive function. Dr. Barber says there isn’t enough research following children after 2 years old, so she’s currently working with Hope for HIE to build a registry to track long-term outcomes.

Your child’s future with HIE

At the beginning of her HIE journey 11 years ago, Pilon felt in the dark and alone. “Max was full-term, in a NICU full of preemies,” she says. “We didn’t have families we could connect with. There was no support.” Fortunately, families have more support today.

And despite limited treatments for HIE, Pilon is optimistic. “The scientific knowledge is advancing at a rapid pace,” she says. “There’s no better time than now in pediatric neuroscience research.”

Pilon notes that Hope for HIE is collaborating with researchers on a handful of treatments in various stages of clinical trials, with more on the horizon. “There’s a research renaissance with HIE. It’s really exciting,” she says. “This is the most attention we’ve had to this diagnosis in quite some time, and it’s been decades in the making.”

References and Further Reading:

Hope for HIE offers information, support and opportunities to participate in clinical trials

National Institutes of Health, National Institute of Neurological Disorders and Stroke, 2023, Hypoxic Ischemic Encephalopathy

Epilepsy Foundation, 2022, Hypoxic Ischemic Encephalopathy (HIE)

Hope for HIE, n.d., What Is HIE?

National Institutes of Health, National Library of Medicine, Saneh, H., et al., 2023, Cord Blood Gas

National Institutes of Health, National Library of Medicine, Sakr, M., et al., 2023, Neonatal Therapeutic Hypothermia

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