Most of the time, a baby who shakes, trembles, or jerks is showing perfectly normal behavior driven by a nervous system that is still maturing. Newborns and young infants have immature nerve pathways, and their brains have not yet developed the fine-tuned control over movement that older children and adults have. This immaturity produces a range of harmless tremors, jitters, and twitches that can look alarming but typically resolve on their own within weeks or months. That said, shaking can occasionally point to something that needs medical attention, so understanding the difference matters.
Jitteriness and the Immature Nervous System
The single most common reason a newborn shakes is plain old jitteriness. You’ll notice rapid, rhythmic trembling of the chin, arms, or legs, often when your baby is crying, startled, or being changed. Jitteriness looks dramatic, but it is considered a benign movement pattern related to the central nervous system still developing after birth. Researchers have found that jitteriness can persist well beyond the first few weeks of life and still be entirely harmless, likely tied to an ongoing maturational process in the brain rather than any underlying disease.1PubMed. Jitteriness beyond the neonatal period: a benign pattern of movement in infancy
One practical clue that jitteriness is benign: the trembling usually stops when you gently flex or hold the shaking limb. This is a key distinction from a seizure, where restraining the limb will not stop the rhythmic movement. Jittery babies also remain fully alert and responsive during episodes, with normal eye contact and no change in breathing. If your pediatrician needs to investigate further, a simple bedside blood-sugar check is typically enough. Research has found that more elaborate blood testing does not add much diagnostic value in evaluating straightforward jitteriness.2PubMed Central. The Clinical Value of Capillary Blood Cartridge-Based Testing in Neonatal Jitteriness: A Re-Evaluation of the Diagnostic Approach
Shuddering Attacks
Shuddering attacks are one of the more unnerving benign movements a baby can make. The baby’s head and upper body suddenly tremble or vibrate for a few seconds, almost like a brief full-body shiver. It can happen multiple times a day. The episodes tend to be triggered by excitement, frustration, or feeding, and they end just as quickly as they start. Throughout the episode, the baby stays fully conscious and aware, with no confusion or drowsiness afterward.3PubMed Central. Shuddering attacks: A benign phenomenon in children
These attacks can easily be mistaken for infantile spasms or myoclonic seizures because they look so similar on the surface. The critical difference is that a neurological exam and brain-wave recording (EEG) are completely normal during shuddering attacks. The condition is distinct from epilepsy and does not respond to anti-seizure medications. In most children, shuddering attacks disappear by age two without any treatment.4Journal of Pediatric Epilepsy. Shuddering Attacks in an Infant Parents mainly need reassurance: the attacks decrease in frequency over time and stop on their own.
Benign Myoclonus of Early Infancy
A closely related movement pattern is benign myoclonus of early infancy, sometimes called benign spasms. This involves brief, shudder-like bursts of tonic movement that mainly affect the trunk and sometimes the head and limbs. Like shuddering attacks, these episodes happen during wakefulness and are often sparked by excitement or frustration. The jerks can range from barely noticeable to more sustained contractions, but EEG recordings during the episodes consistently show no epileptic activity.5PubMed. Benign myoclonus of early infancy
This pattern typically appears in the first year of life and resolves within the first two years. The overlap with shuddering attacks is real, and some researchers consider them part of the same spectrum of harmless infant movement. The important thing is recognition: if a doctor identifies the pattern clinically and sees a normal EEG, no further workup or medication is needed.
Jerking During Sleep
Babies frequently twitch, jerk, or even flail their limbs while sleeping. If you have ever watched your newborn suddenly kick both legs or fling their arms during a nap, you have likely witnessed benign neonatal sleep myoclonus. These jerks can occur in any stage of sleep, and they sometimes affect the whole body in clusters that look genuinely scary.
A hallmark feature is that the movements stop the moment the baby wakes up. In fact, rocking the baby or even repetitive sounds can actually bring the jerks on, and holding the limbs still does not reliably stop them and can sometimes make them temporarily worse. Anti-seizure medications similarly fail to help and may even worsen the jerking, which is a strong clue that this is not epilepsy.6Pediatrics. Benign Neonatal Sleep Myoclonus: A Review of the Literature A review of over 160 cases found that in roughly a third of affected babies, the sleep jerks persisted past three months of age before eventually resolving. That timeline can feel long to a worried parent, but the condition remains benign throughout.
How to Distinguish Benign Tremors from Seizures
The question every parent really wants answered is whether the shaking they are seeing could be a seizure. The short answer: seizures in infants exist, but many movements that look seizure-like turn out to be nonepileptic. Babies can present with movements that closely mimic seizures but require no treatment beyond reassurance.7Advances in Pediatrics. Advances in Pediatrics That said, you cannot always tell the difference at home, so knowing a few practical pointers helps.
Benign tremors and jitters tend to share these features:
- Stimulus-sensitive: They start or worsen with crying, a sudden noise, or a position change.
- Suppressible: Gently holding or flexing the shaking limb reduces or stops it.
- Rhythmic and fast: The movements are fine, rapid trembling rather than slow, jerky contractions.
- Consciousness preserved: The baby maintains eye contact, responds to your voice, and breathes normally.
Seizures, by contrast, often involve eye deviation (the eyes rolling or fixing to one side), color changes in the skin, lip-smacking or unusual mouth movements, and a post-event period of drowsiness or unresponsiveness. Restraining a seizing limb does not stop it. If you observe any of these features, record a video on your phone and contact your pediatrician or head to the emergency room. A short phone video is one of the most valuable tools a doctor can have when evaluating abnormal infant movements.
Low Blood Sugar and Electrolyte Problems
When newborn jitteriness is more than just a maturing nervous system, the most common culprit is low blood sugar. Babies born to mothers with diabetes, premature infants, and those who are small or large for their gestational age are at higher risk. The trembling from low blood sugar looks very similar to ordinary jitteriness, which is why a quick glucose check is standard when a newborn seems unusually jittery.
Less commonly, electrolyte imbalances can cause tremors or even frank seizures. Low calcium and low magnesium are the usual suspects. Magnesium in particular is sometimes overlooked during workups for infant seizures. Its deficiency can produce neurological symptoms, cardiac problems, and skeletal changes. In rare familial forms, magnesium stays persistently low and drags calcium down with it, creating a cycle that triggers seizures until the underlying deficiency is identified and corrected.8PubMed Central. Familial hypomagnesemia with hypocalcemia: a rare cause of infantile seizures
Vitamin B12 Deficiency
One underappreciated cause of infant tremors is vitamin B12 deficiency. This tends to show up in exclusively breastfed babies whose mothers have low B12 levels, whether from undiagnosed pernicious anemia, a vegan or vegetarian diet, or other conditions that impair B12 absorption. Symptoms typically emerge between two and twelve months of age and can include lethargy, poor growth, developmental regression, and movement abnormalities described as tremors, twitches, or myoclonus. Roughly half of affected infants develop some form of abnormal movement.9Pediatrics. Vitamin B12 Deficiency: A Cause of Abnormal Movements in Infants
In a study of 85 cases of infant B12 deficiency, tremor was one of the most common findings at initial examination, present in about three in ten cases. More than a third of babies presented with spells that included apnea, motor seizure-like episodes, or absence-like staring, often within the first two months of life.10Pediatric Neurology. Breastfed Infants With Spells, Tremor, or Irritability: Rule Out Vitamin B12 Deficiency The good news is that B12 replacement can reverse all of these effects, though delays in diagnosis risk permanent developmental harm. If you are breastfeeding and follow a diet that restricts animal products, mention this to your pediatrician so they can check your baby’s B12 status.
Neonatal Abstinence Syndrome
Babies born to mothers who used opioids, benzodiazepines, or certain other substances during pregnancy can develop neonatal abstinence syndrome (NAS), essentially a withdrawal state after birth. NAS commonly produces tremors, excessive crying, poor feeding, and sleep disturbances. In clinical settings, the shaking associated with NAS frequently prompts concern about seizures. However, a study of 40 newborns admitted for seizure-like movements in the context of NAS found that when their brain activity was formally recorded, only three actually had epileptic seizures. The rest were showing nonepileptic tremors, myoclonus during sleep, or rhythmic limb movements that resembled seizures but were not.11PubMed Central. EEG Findings in Infants With Neonatal Abstinence Syndrome Presenting With Clinical Seizures
This means that even in a population at genuinely elevated risk for seizures, the vast majority of trembling episodes were benign nonepileptic movements. That finding has practical implications: treating those movements with anti-seizure drugs would be unnecessary and potentially harmful. Babies with NAS are best managed with supportive care, appropriate scoring tools, and medication targeted at the withdrawal itself rather than at the tremor.
Febrile Seizures in Older Babies
Once your baby passes roughly six months of age, a new category of shaking enters the picture: febrile seizures. These are convulsions triggered by fever, and they affect a small percentage of children between about six months and five years. A common belief is that a rapid spike in temperature is what sets them off, but the evidence actually points more strongly to the peak height of the fever itself as the key factor.12American Journal of Diseases of Children (JAMA Network). Are febrile seizures provoked by a rapid rise in temperature? This matters because parents sometimes blame themselves for not catching the fever early enough, when in reality the speed of the temperature rise is not the decisive trigger.
A simple febrile seizure is typically brief, lasting under five minutes, and involves generalized shaking with loss of consciousness followed by a period of sleepiness. It does not cause brain damage or increase the risk of epilepsy in the vast majority of children. Complex febrile seizures, which are longer, focal, or recurrent within 24 hours, do warrant closer follow-up. If your child has a first-time febrile seizure, your pediatrician will likely want to examine them and may check for the source of the fever but will usually not recommend long-term anti-seizure medication.
The Exaggerated Startle Reflex
All newborns have a startle reflex, known as the Moro reflex, where a sudden noise or movement causes the arms to fling outward and then draw back in. This is entirely normal and fades by about four to six months. In rare cases, however, the startle reflex is exaggerated to the point that a baby stiffens dramatically with every unexpected sound or touch, sometimes leading to brief episodes of rigidity or even falls in older infants. This condition, called hyperekplexia, involves excessive responses to ordinary stimuli and can occasionally be confused with seizures.13PubMed Central. Approach to exaggerated startle reflex: a case of hyperekplexia minor
Hyperekplexia has a genetic basis in many cases, involving mutations that affect how inhibitory signals are processed in the nervous system. It is treatable once recognized, and the episodes are not epileptic. The difficulty is that it sits at the intersection of several conditions that can produce exaggerated startle responses, so a detailed clinical evaluation is needed to pin down the exact cause.
Brain Injury and Encephalopathy
In a small fraction of newborns, tremors or seizures signal that the brain has been injured during or around birth. Hypoxic-ischemic encephalopathy (HIE), caused by oxygen deprivation, is the most commonly discussed cause, but the landscape is wider than that. Genetic mutations, metabolic disorders, immune-mediated conditions, and toxic exposures can all produce symptoms that closely mimic HIE, making accurate diagnosis challenging.14PubMed Central. Beyond hypoxic-ischemic encephalopathy: genetic insights and precision diagnosis in neonatal encephalopathies If a baby has suffered a difficult birth with evidence of oxygen deprivation, the medical team will be monitoring closely for seizures and other neurological signs. These situations are managed in a neonatal intensive care unit with continuous monitoring and, when needed, therapeutic cooling to protect the brain.
Inherited Metabolic Conditions
Very rarely, persistent or worsening movement abnormalities in an infant point toward an inherited metabolic disorder. These conditions involve the body’s inability to properly process certain substances, and they can produce tremors, dystonia, or other abnormal movements alongside developmental regression. Clues that an underlying metabolic condition might be at play include early onset of symptoms, a family history of similar problems, worsening over time rather than improvement, changes in skin or hair, and episodes triggered by illness or fasting.15PubMed Central. Movement Disorders in Inherited Metabolic Diseases in Children
The key distinguishing feature compared to benign tremors is trajectory. Benign infant movements stay stable or improve with time. Metabolic conditions tend to worsen or come and go in response to identifiable triggers like febrile illness or dietary changes. Newborn screening programs catch some of these conditions at birth, but not all. If your baby’s shaking is getting worse rather than better, or if you notice any loss of previously acquired skills like rolling or reaching, prompt medical evaluation is important.
When to Contact Your Pediatrician
Given that the majority of infant tremors are harmless, the challenge for parents is figuring out which ones deserve a call to the doctor. A few practical guidelines can help:
- Eye involvement: If your baby’s eyes roll, deviate to one side, or flutter rhythmically during an episode, seek evaluation promptly.
- Altered awareness: If your baby seems unresponsive, unusually drowsy, or confused after the shaking stops, that warrants a call.
- Cannot be stopped: If gently holding or flexing the limb does nothing to change the movement, it may not be a simple tremor.
- Color changes: Pallor, blueness around the lips, or a mottled appearance during an episode is a reason to seek immediate care.
- Feeding difficulties: Tremors accompanied by poor feeding, vomiting, or failure to gain weight suggest a systemic cause rather than a benign movement.
- Getting worse: Benign tremors stay the same or decrease over weeks and months. If the shaking is intensifying or becoming more frequent, bring it up with your doctor.
Recording a video of the episode on your phone is one of the most useful things you can do before the appointment. Descriptions alone can be difficult to interpret, and most babies will not cooperate by performing on cue in the doctor’s office. A fifteen-second clip showing the actual movement gives your pediatrician far more information than a verbal summary ever could.
Temperature Regulation and Shivering in Newborns
Parents sometimes wonder whether their baby is shaking because they are cold. Interestingly, newborns do not shiver in the way adults do. Adult shivering involves rapid muscle contractions to generate heat, but newborns rely heavily on a different warming mechanism: brown fat, a specialized type of fat tissue concentrated between the shoulder blades and around major blood vessels. When a newborn is exposed to cooler temperatures, brown fat activates to produce heat without the visible shaking you would expect in an older child or adult. Research has confirmed that the interscapular brown-fat region in newborns maintains a stable temperature even when the rest of the body cools during a brief cold exposure.16Nature Communications. BMP8 and activated brown adipose tissue in human newborns
So if your newborn is visibly trembling, it is almost certainly not shivering from cold. Older infants gradually develop the ability to shiver as their nervous systems mature, but in the first months of life, the shaking you see is far more likely to be jitteriness, a startle response, or one of the benign movement patterns described above. If your baby feels cool to the touch and you are concerned about temperature, adding a layer of clothing is reasonable, but the trembling itself is a separate issue.