Hypoxic-ischaemic encephalopathy (HIE)

Hypoxic-ischaemic encephalopathy (HIE) may be diagnosed if your baby’s brain does not receive enough oxygen and/or blood flow around the time of birth.

• ‘Hypoxic’ means not enough oxygen

• ‘Ischemic’ means not enough blood flow

• ‘Encephalopathy’ means it is affecting the brain.

You might also hear it being referred to as ‘asphyxia’, ‘birth asphyxia’ or ‘perinatal asphyxia’.

Low oxygen and/or blood flow to a baby’s brain happens most often before or during birth, but it can also happen shortly after birth.

HIE affects the brain, but low oxygen or blood flow can also cause problems in the lungs, liver, heart, bowel and kidneys.

When diagnosed, HIE is graded as mild (stage 1), moderate (stage 2) or severe (stage 3). Where HIE is graded as moderate or severe, it can result in long-term disability and in some cases can sadly result in death. We have more information about making critical care decisions, palliative care and bereavement, and links to other sources of support further down this page.

If your baby has been diagnosed with HIE, you are likely to have lots of questions about what caused this, what treatment your baby will need and how the condition may affect them in the long term. Talk to the staff looking after your baby. They will be able to answer your questions and explain what is happening.

What causes HIE?

It is not always possible to know what causes HIE. It can be caused by complications during pregnancy such as:

• Issues with blood flow to the placenta

• Heart disease

• If the birthing parent suffers from high blood pressure

• Issues with the baby’s lungs

• Pre-eclampsia

• If the birthing parent suffers from alcohol or substance disorder

And it can be caused by complications at or around the time of birth such as:

• The placenta coming away from the uterus wall too soon (placental abruption)

• Tearing of the uterus (uterine rupture)

• Having an unusually long labour (prolonged labour)

• Your baby’s shoulders getting stuck behind the pubic bone during delivery (shoulder dystocia)

• Cord entanglement or compression, where the umbilical cord is unable to function correctly.

HIE can occur at any stage during a pregnancy, during labour or shortly after birth. During labour, the medical team will be monitoring your baby’s breathing and heart rate. After delivery, Apgar scores (a general well-being check on new-born babies) may indicate early concerns.

HIE is usually diagnosed in the first few days after birth. A doctor will make the diagnosis based on certain signs, which are different depending on how severe the condition is.

What are the signs of HIE?

Doctors will look for some of the following signs in your baby:

• Being hyper-alert – they may appear over-awake, even with little sleep

• A reduced level of awareness or responsiveness or being overly sleepy

• Being irritable – they may start to dislike noise, touch and light

• Being floppy or stiff

• Having unusual movements or seizures

• Having a weak cry

• Having pauses in breathing (apnoea)

When diagnosed, HIE is sometimes referred to by the Sarnat Scale as Stage 1 (mild), 2 (moderate) or 3 (severe). The grade of HIE will determine the treatment that is recommended for your baby.

What tests might my baby have?

If your baby's healthcare team is concerned about the possibility of HIE, they may arrange further tests. These might include (but are not limited to) the following:

• Cerebral Function Monitoring (CFM) – CFM uses sensors to record brain activity. It is used to show the early effects of HIE on your baby’s brain, and can be also used to decide if your baby needs therapeutic hypothermia (cooling) treatment.

• Head ultrasound scan (cranial ultrasound) – A head ultrasound scan is used to look at images of your baby’s brain. It can be used to show problems such as bleeding, stroke or swelling.

• Checking cord blood gas levels – A buildup of acid in the umbilical cord artery may indicate there is a risk of damage to the brain.

• MRI scan – An MRI scan uses magnetism to build up a very detailed picture of areas of your baby’s brain. It is used to see if any damage has been done to your baby’s brain. It is usually performed after cooling treatment (see below).

Treatment for HIE varies depending on how severe it is believed to be.

Mild HIE (Stage 1)

Most babies with mild HIE recover quickly. If your baby has mild HIE, doctors will monitor them closely to check that they are stable and ensure they do not need any more treatment.

Should your baby need additional support, they may be referred to one or more Allied Health Professionals (AHPs) to provide support and advice during your baby's inpatient journey and, if needed, continue to provide early intervention support on discharge. Allied Health Professionals include services such as physiotherapists, occupational therapists, dieticians and speech and language specialists.

Moderate to severe HIE (Stages 2 and 3)

If your baby has moderate to severe HIE, there is a risk of long-lasting damage to the brain, or death.

To reduce this risk, babies with moderate or severe HIE are likely to receive a treatment called therapeutic hypothermia or cooling therapy, which needs to be started within the first 6 hours after birth. A special cooling mattress is used to lower the baby’s temperature to between 33°C and 34°C for 72 hours. The mattress is filled with fluid that can be cooled or warmed according to your baby’s needs. This helps to slow damage to brain cells and prevent further toxins from forming, limiting injury to the brain.

Your baby’s temperature will be monitored closely to ensure that it stays at the right level, and cooling will usually be continued for 72 hours before rewarming. Your baby will be rewarmed over a period of 12 hours. During the cooling period, the team will also closely monitor your baby’s heart rate and blood pressure, perform blood tests and use a Cerebral Function Monitor (CFM) to record brain activity. They will also monitor your baby’s medication and give pain relief and anti-seizure medication if needed.

Some parents are worried that they will not be able to hold or have skin-to-skin with their baby during cooling treatment. You may be able to hold or touch your baby during cooling, but this depends on how unwell your baby is and how much equipment is attached to them. Talk to your baby’s neonatal team to understand how you can be involved.

During this time, you can also help your baby by expressing breastmilk and talking and reading to them.

Research shows that cooling can benefit some babies with moderate or severe HIE who are born after 36 weeks, and reduces the risk of long-term disability.

Knowing that your baby is having this treatment can be frightening. We also know that sometimes treatment is needed urgently, and parents don’t always understand what is happening or why.

The team looking after your baby is there to help, and you can ask them questions. For example:

• What does cooling involve?

• What are the benefits of cooling?

• Are there any risks of cooling, and how likely are they to happen?

• What care will my baby need after the treatment?

• What might happen if my baby doesn’t have the treatment?

• How will treatment affect my baby’s ongoing development?

• How can I be involved in my baby’s care right now?

While some babies with HIE recover fully and have no long-term symptoms, others may need further help and support from healthcare professionals, such as physiotherapists or speech and language therapists.

If your baby has had cooling treatment, they are likely to have follow up tests to monitor their response to the therapy. You will meet with your baby’s doctor to talk about your baby’s results. They will also talk to you about your baby’s behaviour and progress. This information will be used to make a plan for further assessment and follow-up. The amount of appointments your baby will have will depend on their needs.

All babies who have been affected by moderate or severe HIE will need their development monitored closely, particularly during the first two years of their life.

When your baby is between 18 months and 2 years old, a healthcare professional will look at your baby’s progress in the following areas of their development:

• Motor (your baby’s ability to move around and hold and grasp objects).

• Sensory (your baby’s sight, touch, taste, smell and hearing).

• Language (your baby’s ability to communicate and understand language).

• Cognition (how your baby learns to think and reason).

This assessment can help to provide a better understanding of how your baby is developing and can help to answer any concerns that you may have.

Very occasionally, babies with mild HIE seem fine at first but show signs of delayed development as they grow older. If you notice any concerns about your baby’s development, contact your baby’s care team for advice and support.

Some babies may develop cerebral palsy, which is a physical condition that affects movement, posture and coordination. Some babies may develop problems with their eyesight and hearing or have learning or behavioural difficulties. Some babies will go on to develop epilepsy, which is a condition that affects the brain and causes seizures.

Knowing that your baby could have long-term problems as a result of HIE can be frightening and overwhelming at first, but there is support available. At the bottom of this page we have listed some organisations that can help.

Sadly, some babies will die of HIE. We have more information about making critical care decisions, palliative care and bereavement, and link to some more sources of support further down this page.

Having a baby with HIE is always unexpected.

When your baby is unwell and in intensive or special care, it can be a stressful and worrying time. Parents have told us that it made them feel out of control of their situation. Some parents feel grief or loss as they let go of hopes and plans they had.

How you feel and process what has happened to you and your baby might be different to others who face similar challenges. Feeling this way is common.

If you are unsure about any part of your baby’s diagnosis, treatment or care, the staff on the unit will help you. It is okay to ask again if you need information repeated or made clearer. The team will understand and want to support you.

Here are some links to charities and organizations that can offer more support. Social media websites such as Facebook may also be able to provide information about local support groups and charities where you can talk to other parents who have a baby with HIE. Your unit may also be able to provide you with this information.

• Peeps HIE charity – Provides support to parents affected by HIE, and raises awareness.

• Hope for HIE – Works to improve the quality of life for children and families affected by HIE through useful resources and support.

• The Birth Trauma Association – Provides support to women who have had a traumatic birth experience.

• The Rainbow Trust – Provides emotional and practical support to families who have a child with a life-threatening or terminal illness.

• Sands - A charity that supports anyone affected by the death of a baby.

• Scope - A charity that supports disabled people and their families through practical information and support, particularly at the time of diagnosis.

• Together for Short Lives – A charity for children with life-threatening and life-limiting conditions.

• Epilepsy Action – Provides advice and support to anyone affected by epilepsy.

Could you take part in research with Bliss and The National Perinatal Epidemiology Unit (NPEU)?

Bliss and The National Perinatal Epidemiology Unit (NPEU) are working together on the DOLFIN trial. DOLFIN stands for Development Outcomes of Long-term Feed Supplementation in Neonates. It is a clinical trial run by the National Perinatal Epidemiology Unit (NPEU), a research unit established at the University of Oxford in 1978, and sponsored by The Newcastle upon Tyne Hospitals NHS Foundation Trust.

The DOLFIN trial is looking to find out whether adding a daily nutrient (food) supplement to the milk or food of babies with HIE or who are born very early can help improve their brain development, and their neurological child development (such as how they think, communicate, play and interact with others). Bliss are DOLFIN study co-investigators and have worked on the development of resources for parents.

The DOLFIN trial is running in over 30 UK neonatal units. If your baby is receiving care in one of the neonatal units taking part in DOLFIN, they may be able to take part.

Here is a video introduction to the DOLFIN trial.

For more information, visit the DOLFIN's Information for Parents page.