Infant Shudder Syndrome and Autism, Do They Relate?

Infant shudder syndrome is difficult to diagnose because its symptoms are vague and may mean different things in babies. Sudden shivering is normal for some babies because of their immature nervous systems. They also twitch as their fine motor skills develop. In more serious conditions, babies with oxygen deprivation upon birth could manifest cerebral palsy. Shivering and spasms may also lead to seizures and increases the baby’s risks for autism. 

What is infant shudder syndrome?

We have all been there – watching babies tirelessly as they sleep, especially after bringing them home from the hospital. Every delicate twitch of their lips, flutter of their eyelids, and heaving of their tummy as they breathe means something to us. 

And for most parents, a sudden shudder or tremor in their newborn can be disturbing. Sometimes they would grunt and stiffen their legs or strain and shiver. But, when can you say it is just a normal developmental stage or it means something serious?

Infant shudder syndrome is a benign, nonepileptic event in children.

It’s the involuntary movement of the head and upper extremities that occur suddenly from normal activity. It does not impair consciousness, and the quivering does not last long, which distinguishes it apart from epilepsy. 

Sometimes, shudder attack is misdiagnosed as a rare form of epilepsy. 

Common causes of shudder attack

Some babies randomly shudder as part of their development while others do because they experience seizures. So, it is important to look at the following common causes and symptoms.

Immature nervous system

Babies twitch and flinch involuntarily because of the impulses in the nerve cells.

As you may know, the nerve cells in the brain are responsible for sending messages throughout the body through electrical impulses. When the electrical impulses are sudden and excessive, it causes jerky and seizure-like movements. 

As days go by, the baby’s movement will become more fluid as the nervous system becomes more mature. 

Fine motor skill development

An infant girl is on her tummy practicing her fine motor skills

Twitching is a part of development at different stages in the baby’s life.

It helps their little body become more coordinated. For example, their head may have a jerky movement in preparation for holding their heads.

It happens in different parts of the body at different developmental stages. Fine motor skill development occurs when their wrists and fingers seem to shudder. 

Startle reflex

Moro, or startle reflex, is just one of the innate reflexes the baby is born with and is crucial for survival.

These are involuntary reactions to movements and triggers like sound, light, sudden movements, or being touched. Moro reflex is what scares new parents the most as the baby lifts and curls his arms and legs and throws his head back. 

Moro reflex is a normal process that every baby should undergo. But when it involves only one side of the body or the baby does not exhibit the reflex at all, then parents should be alarmed.

This could mean infections, muscle weakness, childbirth injury, spastic cerebral palsy, or peripheral nerve damage. 

Sleep myoclonus

An infant baby is lying on his back with a pacifier in his mouth, trying to fall asleep.

Myoclonus refers to involuntary muscle movement like hiccups. It also occurs when one is close to falling asleep or just waking up.

The shaky and shuddering movement happens to everyone and rarely causes a problem.

Sometimes, it is triggered by external stimuli like noise and movement. It usually resolves within a year after birth. 

Other reasons for shudder spells

The weird shivering and jerking that the baby exhibits may also be caused by:

  • Disagreement to activities like a diaper change or bathing
  • Your baby is cold
  • Hunger
  • Low blood sugar or hypoglycemia 
  • Cerebral palsy

Babies with low blood sugar have tremors and show other symptoms. It may include a bluish tint to the skin and lips, tiredness, and disinterest in feeding. When you noticed these signs, contact the pediatrician immediately. 

Infant shudder vs. seizure

Shudder attacks are brief episode of shivering that resembles seizure.

The main difference between them is that shudder does not occur during sleep. The baby is also alert and conscious during a shudder attack that could last only for a mere 5 to 15 seconds. 

Seizure, on the other hand, has tremors that last for at least one minute. The child would be staring into nothing, shows no emotion, and is unresponsive.

You cannot also stop the jerking even if you hold his hand, unlike in a shudder attack. He will also become sleepy and lethargic after a seizure. 

A chronic seizure, or those that occur more than once, is diagnosed as epilepsy. 

A pediatric neurologist can differentiate and diagnose infant shudder symptoms and seizures. The pediatrician may refer you to one if he suspects it is necessary for your baby.

You can expect a series of tests such as:

  • Blood and urine test for infection
  • EEG (electroencephalogram) for brain activity
  • VEEG (Video EEG) 
  • CAT scan, MRI, or other scans to look inside the brain

Infant shudder vs. autism

Autism is also a different thing from an infant shudder attack. Shudder spell is involuntary while children with autism engage in rhythmic motions to soothe themselves.

Autism is diagnosed when the baby is around 2 years old while shudder attack is fairly common in newborn infants. 

According to Raynes and Lawn, babies who experience shudder spells or infantile spasms are at higher risk of seizure later in life. And they are also likely to experience cognitive delays and autism since the shudder spell may be an early manifestation of the condition. 

To avoid serious conditions, talk to a pediatrician about the baby’s shudder symptoms for early intervention. 


Can caffeine be a possible cause of a baby’s shuddering?

It is uncommon but could be possible. If you are breastfeeding, an amount of caffeine passes into the breast milk. In large amounts (more than 300 mg or 3 cups a day), it can build up in the infant’s body and cause them to twitch.

My baby is shaking, trembling, and crying. Is it infant shudder syndrome?

Shaking, trembling, and wailing can be a sign that your baby is hungry. Stiffening of the body shows a late sign of hunger.

Try feeding your baby, and if the symptom does happen anywhere near feeding time, he is likely only hungry.

How long will the shudder symptom last?

In most cases, the shuddering will stop after a few months to a year without inherent consequences.


Babies have weird movements, and it varies from child to child as they develop. The signs that they manifest can sometimes send parents to their wit’s end. But, it is always you as a parent who holds the better judgment. If you think your baby needs to see the doctor, do not hesitate to do so. 

Jot down the symptoms that you noticed like time duration if your baby has this sudden shivering. You can also take a video when it happens to show your pediatrician on your next visit. 

Don’t worry, most of the scary things you discover in your baby are likely just part of his development. As his body and its processes become more mature, he will figure out its interaction with his environment. And most of these things disappear unless there is an underlying serious condition behind it. 

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Ann Marie is a licensed nurse in the Philippines. She experienced handling and assisting deliveries of newborns into the world. She also trained in labor rooms and pediatric wards while in nursing school - helping soon-to-be mothers and little kids in the process. Though not a mother by nature but a mother by heart, Ann Marie loves to take care of her younger cousins as well as nephews and nieces during her free time.

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