Kernicterus is a rare but serious form of brain damage that develops in newborn babies and very young infants when severe jaundice causes bilirubin levels to become dangerously high. Although the condition develops early in life, some of its lasting effects may be recognised during the toddler years, when children begin reaching important milestones for movement, speech, hearing and development.

For parents, these signs are not always easy to connect straight away. A baby may have developed severe jaundice shortly after birth, but some of the longer-term effects of kernicterus may only become clearer as your child develops. You may notice delays with walking, movement, speech, hearing, feeding or development, especially when comparing your child's progress with expected milestones.

This guide explains the signs parents may notice as their child grows, what to do if you are worried, and how medical negligence can cause kernicterus. It also explains what steps you can take if your child developed kernicterus after doctors, midwives or nurses failed to check, monitor or treat newborn jaundice properly.

If you are worried about your child's health or development, speak to your GP, health visitor or paediatrician as soon as possible. If you believe that earlier failures in care contributed to your child's condition, JMW's specialist kernicterus solicitors can help you understand what happened and whether you may be able to make a clinical negligence claim.

What Is Kernicterus?

Kernicterus is a serious condition that can develop when a newborn baby has too much bilirubin in their blood. Bilirubin is a yellow pigment that forms when red blood cells break down. A baby's liver usually processes bilirubin so it can leave the baby's body, but newborn babies are still developing and their liver may not always manage this quickly enough.

When bilirubin levels become very high, unconjugated bilirubin can move from the baby's blood into brain tissue. This can happen if the blood-brain barrier does not stop the bilirubin from entering the brain. Once this happens, the baby may develop bilirubin encephalopathy. If the damage becomes permanent, it is known as kernicterus or chronic bilirubin encephalopathy.

Newborn jaundice is often the first visible sign that bilirubin levels are raised. It can cause yellow colouring in the baby's skin, eyes or gums. Jaundice in babies should be investigated with a blood test to measure bilirubin levels, and doctors, midwives and nurses should remain aware of the condition during the first days of a baby's life.

Many babies develop jaundice, and it is often treated safely. However, severe jaundice needs urgent assessment because untreated jaundice can lead to brain damage and lifelong kernicterus complications. Early diagnosis through monitoring and prompt treatment of jaundice is crucial to manage this correctly.

You can learn more about the causes of kernicterus by reading our guide to what causes kernicterus in newborn babies.

How Does Severe Jaundice Lead to Kernicterus?

Severe jaundice can develop when bilirubin builds up faster than the baby's body can clear it. This may happen because the baby's red blood cells break down quickly, the baby's liver is not processing bilirubin well, or the baby is not feeding enough to pass bilirubin out of the body.

Doctors and midwives should check for jaundice in newborn babies, especially in the first few days after birth. If a baby develops jaundice, they may need a test to confirm how much bilirubin is in the baby's blood. In some cases, doctors will check the total serum bilirubin level through a blood test.

If bilirubin levels are high, the baby may need light therapy, also called phototherapy. This uses a special blue light to help break down bilirubin so the baby's body can remove it more easily. If bilirubin levels are extremely high, the baby may need care in a neonatal intensive care unit and, in serious cases, an exchange transfusion using donor blood.

Kernicterus is rare, and prompt recognition and treatment of severe jaundice can prevent it from developing. If doctors, midwives or nurses miss jaundice symptoms, delay a bilirubin test, fail to monitor bilirubin levels or do not provide treatment quickly enough, a child may develop kernicterus as a birth injury.

What Are the Symptoms of Kernicterus?

Kernicterus can cause immediate symptoms when bilirubin levels are dangerously high, as well as lasting effects if the brain has been permanently damaged. In newborn babies, the first concern is usually severe jaundice and signs of acute bilirubin encephalopathy.

What are the early kernicterus symptoms?

In newborn babies, signs of acute bilirubin encephalopathy can include:

• Severe jaundice, with yellow colouring in the baby's skin, eyes or gums
• Poor feeding or difficulty feeding
• Extreme sleepiness or lethargy
• A high-pitched cry
• Fever
• Unusual stiffness or floppiness
• Muscle spasms
• Unusual eye movements

These symptoms need urgent medical attention. A baby with severe jaundice or signs of acute bilirubin encephalopathy should be assessed quickly by a doctor, paediatrician or neonatal team.

You can read more about the early warning signs in our guide to the symptoms of kernicterus.

If kernicterus causes permanent brain damage, the effects can continue as the child develops. Problems with movement, hearing, vision, feeding or communication may become more apparent as the child grows and more is expected of them developmentally.

What Are the Main Kernicterus Symptoms in Toddlers?

In toddlers, the lasting effects of kernicterus most commonly become apparent through difficulties with movement, muscle control, hearing, speech, vision, feeding and development. The exact signs will depend on which areas of the brain were affected and the extent of the injury.

Movement and muscle control problems

Kernicterus can cause problems with muscle tone, movement and coordination. A toddler may have stiff muscles, floppy muscles or unusual posture, and experience writhing movements or involuntary muscle spasms. These difficulties may become particularly noticeable as the child learns to sit, crawl, stand and walk more independently.

Parents may notice that their child:

• Is late to sit, crawl, stand or walk
• Moves in an unusual or uncontrolled way
• Struggles with balance
• Has tight or stiff arms or legs
• Arches their back or holds their body awkwardly
• Finds it difficult to use their hands for play, feeding or holding objects

Some children who live with the long-term effects of kernicterus develop movement problems linked to cerebral palsy. This can affect how they move, sit, stand, walk and use their hands.

Hearing, speech and communication difficulties

Kernicterus can cause hearing loss or auditory neuropathy, where the ear detects sound but the brain has difficulty processing it. In toddlers, this may become clearer when a child does not respond to sounds or their development of speech is delayed.

Parents may notice that their child:

• Does not react when their name is called
• Does not respond to everyday sounds
• Has delayed speech
• Finds it difficult to copy sounds or words
• Struggles to follow simple instructions
• Uses fewer words than expected for their age

Hearing problems can also affect communication, play and learning. If you are worried about your toddler's hearing or speech, speak to their GP, health visitor or paediatrician.

Vision and eye movement problems

Kernicterus can also affect vision and eye movement. Some children have difficulty looking upwards, tracking moving objects or controlling where their eyes move.

Parents may notice:

• Unusual eye movements
• Difficulty following toys or faces
• Problems looking upwards
• Concerns about focus or visual attention

These signs should be raised with a GP or paediatrician, particularly if your child had severe jaundice as a newborn.

Feeding and swallowing difficulties

Some toddlers who live with the effects of kernicterus have difficulty chewing, swallowing or managing different food textures. This may be linked to problems with muscle control.

Signs can include:

• Difficulty feeding
• Coughing or gagging when eating or drinking
• Dribbling more than expected
• Taking a long time to eat
• Struggling with certain textures
• Needing more help with feeding than other children of a similar age

Feeding difficulties should be discussed with a GP, health visitor or paediatrician. Your child's medical team can assess their needs and advise on any appropriate specialist support.

Developmental and learning delays

Some effects of kernicterus become more noticeable during the toddler years because this is when children are developing skills such as walking, talking, playing and understanding instructions. Parents may therefore first recognise a clear difference between their child's development and expected milestones at this stage.

Parents may notice delays with walking, speech, play, attention, understanding or day-to-day tasks.

A developmental delay does not always mean a child has kernicterus, and there can be many possible causes. It is important to seek medical guidance if you identify any concerns about your child's development.

You can learn more about how the condition can affect children as they grow in our guide to the long-term effects of kernicterus.

What Risk Factors Can Increase the Chance of Kernicterus?

Several risk factors can make severe jaundice more likely. These do not mean a baby will develop kernicterus, but they do mean doctors, midwives and nurses should take care to check the baby's bilirubin levels and respond quickly if jaundice develops.

Risk factors can include:

• A baby being born prematurely
• Jaundice appearing within the first 24 hours after birth
• Poor feeding or too few wet nappies
• Bruising during birth, which can lead to more red blood cells breaking down
• Blood type incompatibility between mother and baby
• Rh disease or an Rh negative blood factor issue
• Haemolytic disease, where red blood cells break down too quickly
• A sibling who previously needed treatment for newborn jaundice
• Certain rare disorders that affect how the baby's body processes bilirubin

Babies with darker skin can also face a higher risk of jaundice being missed, because yellow colouring in the baby's skin may be harder to see. On darker skin tones, jaundice may be more noticeable in areas such as the whites of the eyes or inside the mouth. Parents should seek medical advice if they notice jaundice symptoms or if their baby seems unusually sleepy, feeds poorly or is not producing enough wet nappies.

What Should Parents Do if They Notice Possible Symptoms?

If a newborn baby shows signs of severe jaundice or acute bilirubin encephalopathy, they need prompt medical assessment. If your child is older and you are concerned about their movement, hearing, feeding, speech, vision or development, speak to their GP, health visitor or paediatrician.

For newborn babies, urgent signs can include:

• Yellow colouring that becomes stronger or spreads
• Yellow colouring in the eyes or gums
• Poor feeding
• Extreme sleepiness
• A high-pitched cry
• Fever
• Stiffness, floppiness or muscle spasms
• Fewer wet nappies than expected

Parents should follow the NHS guidance on newborn jaundice and seek appropriate medical attention if they are concerned about these signs.

For toddlers, it can help to keep a written note of your concerns, including when you first noticed them, how often they occur and whether they are changing over time.

It is also useful to tell the doctor, health visitor or paediatrician about any history of severe newborn jaundice, including whether your child needed light therapy, bilirubin tests or neonatal care. This can provide useful context when their development is assessed.

A medical review can identify whether further assessment is appropriate and what support your child may need.

How Can Medical Negligence Cause Kernicterus?

Kernicterus is usually preventable when severe jaundice is recognised, monitored and treated in time. Medical negligence may be involved if a doctor, midwife, nurse or hospital team failed to provide a reasonable standard of care and this caused or contributed to brain damage.

Examples of medical negligence in kernicterus cases may include:

• Failing to check a newborn infant properly for jaundice
• Missing jaundice, including where yellow colouring may be harder to identify on darker skin
• Not arranging a bilirubin test when jaundice was suspected
• Failing to monitor bilirubin levels after a baby developed jaundice
• Not acting when the baby's bilirubin level was dangerously high
• Delaying light therapy or other treatment
• Not escalating care to a paediatrician or neonatal team
• Discharging a baby without appropriate checks, advice or follow-up
• Not responding appropriately when parents raised concerns about poor feeding, sleepiness, yellow colouring or other kernicterus signs

Where a child is now living with the long-term effects of kernicterus, a medical negligence investigation will consider the care provided when their jaundice developed. This may include whether doctors, midwives or nurses recognised the signs, checked and monitored bilirubin levels appropriately, and provided treatment soon enough to prevent permanent brain damage.

When care falls below a reasonable standard and this causes or contributes to a child developing kernicterus, the family may be able to make a medical negligence claim. A claim can investigate what happened and provide compensation that reflects the child's long-term needs.

What Should You Do if You Think Your Child's Kernicterus Was Caused by Medical Negligence?

If you believe your child's kernicterus was linked to their care for newborn jaundice, you can speak to a medical negligence solicitor about what happened. This does not affect your child's current medical care. The legal process separately considers whether doctors, midwives, nurses or the hospital team missed opportunities to prevent the injury.

You may have concerns because:

• Your baby's jaundice appeared early, but no urgent action was taken
• You raised worries about your baby's yellow skin colour, feeding, sleepiness or behaviour
• Your baby was discharged before their bilirubin levels were appropriately checked
• A bilirubin test was delayed or not carried out
• Your baby's bilirubin levels were high, but treatment was not started quickly enough
• Your baby needed urgent treatment after their condition worsened
• Your child now has developmental signs that appear linked to earlier severe jaundice

JMW helps families investigate whether earlier care fell below a reasonable standard. We start by gathering evidence, including your child's medical records, details of appointments, bilirubin test results, discharge notes and your own account of what happened. Depending on our review of the records, we will instruct independent medical experts to address the care your child received and the impact of this. They will provide their opinion on whether a reasonable standard of care was met.

A kernicterus diagnosis can have a lifelong impact on a child and their family. Compensation from a successful claim can reflect needs such as care, therapies, specialist equipment, adapted accommodation, educational support and other losses caused by the injury.