Medical Malpractice
This page is about babies with hypertonia. This condition, also called stiff baby syndrome, is when the baby stiffens her body, most notably her legs, and arms, mainly when being picked up. There are many causes when a baby is stiff, and most resolve over time. Stiff, tense babies are extremely common. But in rare cases, a stiff baby is a sign of a birth injury.
In this article on hypertonia:
Finally taking your baby home from the hospital is an incredible moment that symbolizes a new chapter for your family and begins the journey of raising a child. You may be alarmed if your baby is unusually stiff within the first few days of being home.
Most likely, it is not a big deal, mainly if your birthing process was not traumatic. This cannot be underscored enough. Most parents worry about a stiff baby having nothing to worry about.
But if your baby is abnormally stiff, there is a slight possibility that this is a symptom of a more serious underlying problem. Clinical muscle stiffness is known as hypertonia.
The birth injury and cerebral palsy lawyers at Miller & Zois may be able to help you if you believe your baby was injured as a result of a medical error during childbirth. Our lawyers have years of experience handling these medical malpractice claims.
Below, we discuss the possible causes of stiff baby syndrome and its outcomes for patients, citing recent medical literature. To contact us for a free consultation about your case, call (800) 553-8082 or fill out this brief online form.
Harmless Reasons Why Your Baby Appears Stiff
There could be several reasons why a baby might appear stiff that feel like a big deal to parents – especially new parents – that are not a big deal:
- Startle reflex (Moro reflex): It’s a natural reflex for newborns where they might react to loud sounds or sudden movements by throwing back their head, extending their arms and legs, crying, and then pulling their arms and legs back in.
- Pain or discomfort: Okay, pain is not harmless, but babies will have pain and discomfort for various non-serious reasons and may appear stiff.
- Overstimulation: In some cases, if a baby is overstimulated or overwhelmed, they might arch their back and become stiff.
- Sleeping Position: Sometimes, after sleeping in a particular position, a baby might momentarily seem stiff upon waking, similar to how adults feel after sleeping in an awkward position. So you might see the baby’s legs stiffen when lying down. You sometimes see a very normal baby that stiffen its legs and arms when lying down.
- Physical Development: As infants grow, they start developing muscle tone and might appear stiff as they explore and adjust to their body’s new abilities.
- Feeding: Some babies might stiffen their bodies during or after feeding, especially if they are experiencing discomfort from gas.
- Emotions: Just like adults, babies can tense up when upset, frustrated, or angry, making them appear stiff. Angry babies often stiffen their legs and arms, turn red, and appear tense.
- Cold: If a baby is cold, they might tense up their body, causing them to feel stiffer than usual.
When Parents Notice a Baby Seems Stiff
It is completely normal for parents to worry when their baby does something that feels “off.” Many first notice stiffness in everyday moments: a baby locking their legs while lying on their back, arching stiffly when picked up, or clenching their arms and fists during feeding. Sometimes these movements are just ordinary reflexes or a baby exploring how their muscles work. In fact, in the vast majority of cases, occasional stiffness is nothing to be alarmed about.
Concern arises when stiffness persists, making it difficult to cuddle or feed comfortably, or when it is accompanied by other signs, such as constant irritability, missed milestones, or trouble moving normally. That is when doctors begin to talk about hypertonia, a medical term for unusually high muscle tone that we will talk about next. Parents sometimes call this “stiff baby syndrome.”
Most babies who stiffen now and then will grow out of it without lasting problems. But persistent stiffness deserves careful medical attention because, in rare cases, it can be an early clue of neurological issues or even a birth injury that occurred during delivery. Getting answers quickly matters — not because every stiff movement means something is wrong, but because early intervention can make a significant difference if there is an underlying problem.
Other Causes of Stiff Baby Syndrome
Hypertonia
What is hypertonia and what does it have to do with why my baby is so stiff? Hypertonia is an umbrella term that describes when there is an abnormally high muscle tone in the infant’s body. High muscle tone causes the baby to be stiff and rigid, especially when held. Newborn babies with this condition may have difficulty with mobility and flexing. A stiff baby is often called hypertonic or is said to have “stiff baby syndrome.” The stiffness usually gets better when the newborn is asleep.
Experiencing muscle stiffness or rigidity can be a symptom of several different conditions that range in severity, some of which are discussed in detail below. Hypertonia is usually caused by an insult to the brain, spinal cord, or nervous system. Trauma to the baby’s head, strokes, brain tumors, toxins, neurodegeneration, such as Parkinson’s disease, and neurodevelopmental abnormalities, such as cerebral palsy, can cause hypertonia.
There are three types of newborn hypertonia: spasticity, rigidity, and dystonia, each with different symptoms and underlying causes when a baby stiffens its body. Many healthcare providers use spasticity and hypertonia interchangeably. Spasticity is a subtype of hypertonia that involves exaggerated reflex responses. Rigidity is when there is muscle resistance across the range of motion. Involuntary, repetitive muscle contractions characterize dystonia.
While it’s essential to be concerned about your baby’s health, many causes of stiff baby syndrome can be completely harmless and easily fixed. With more severe conditions, there are available treatments that can manage your baby’s symptoms. Common treatments for hypertonia in a newborn include seeing a physical therapist, muscle spasm medications, and surgeries. If you had a prior pregnancy with no complications, there is a much lower chance that your baby will develop one of the conditions listed below.
“Most of the conditions that cause newborn hypertonia are curable or treatable.”
If you’re concerned about your baby, the best way to proceed is to talk to your pediatrician as soon as possible. There are many explanations for why your baby is hypertonic, and your pediatrician can conduct the appropriate diagnostic tests to determine what is causing the hypertonia. We discuss some common causes of newborn hypertonia below.
Cerebral Palsy
Cerebral palsy (CP) is a medical condition that can develop due to brain damage during childbirth. During delivery, if the baby experiences reduced blood flow to the brain over an extended period, the baby becomes hypoxic. Hypoxia is the term that describes when a part of the body is deprived of an adequate oxygen supply. This lack of oxygen damages the brain’s motor control centers and causes CP. The symptoms of this condition include muscle stiffness, rigidity, and spasticity.
“Cerebral palsy is one of the most common birth injuries cited in medical malpractice cases.”
There are four types of CP. Spastic cerebral palsy is the most common type of cerebral palsy, characterized by hypertonic muscles. Having spastic cerebral palsy may affect the child’s ability to move, walk, or use their hands because they don’t have control of their muscles. Their muscles may also have involuntary movements or be pulled towards a certain side of the body. This condition is permanent, but various treatments can mitigate and manage the symptoms.
Cerebral palsy is rarely the underlying cause of stiff baby syndrome.
Erb’s Palsy and Shoulder Dystocia
Erb’s palsy is a different birth injury involving the nerves’ function. Erb’s palsy is not caused by lack of oxygen but instead occurs when the nerves in the baby’s upper arm, shoulder, or side of the neck (known as the brachial plexus) are physically damaged while descending through the birth canal. This nerve damage often happens when a baby experiences shoulder dystocia during delivery.
Shoulder dystocia is when the baby’s shoulders get stuck during labor, typically on the mother’s pelvic bone. Medical professionals have to perform certain maneuvers to deliver the baby, which can be damaging. Pulling on the head, using forceps, or using vacuum extraction may damage the nerves in the brachial plexus and limit or completely restrict the communication between the brain and the shoulder, arm, and hand. For this reason, shoulder dystocia can result in medical malpractice. Erb’s palsy symptoms include muscle stiffness, arm weakness, decreased grip, impaired circulatory development, or paralysis of the arm.
Kernicterus
Kernicterus is a type of preventable brain injury that occurs due to untreated jaundice in newborn babies. Most babies experience jaundice shortly after birth, with 60-80% of infants in the United States being affected. Premature babies are more likely to have jaundice. The condition is usually harmless, and most babies are quickly treated with no complications. Jaundice is easily recognizable because it causes a baby’s skin to turn a yellow-orange color. This skin color comes from a build-up of bilirubin in the blood, a waste product produced when your liver breaks down old blood cells.
With proper monitoring after birth, jaundice is not a cause for concern. It’s a natural part of the baby’s body to adjust to the world after birth.
In rare cases, if the jaundice is not treated by the child’s doctor and is allowed to progress, a baby can accumulate high bilirubin levels, leading to brain injury. Since mild neonatal jaundice is common, healthcare providers have neglected to screen for excessive bilirubin in a baby’s blood.
Kernicterus symptoms include reduced muscle tone, muscle stiffness and spasms, fever, and unusual eye movements. If your baby exhibits kernicterus signs, seeking medical help to prevent serious complications is essential.
Infantile Spasm
Infantile spasms, also known as West syndrome, is a rare type of epilepsy in infants. It’s characterized by sudden, involuntary muscle spasms involving the entire body or just parts of it.
Episodes of infantile spasm typically emerge during the first year of life, usually between four to eight months. Early diagnosis and treatment are essential because infantile spasms can be associated with developmental regression and may evolve into other types of epilepsy if not addressed.
The most noticeable symptom is the presence of the spasms themselves. They often occur upon waking. A baby might bend forward, and the body may stiffen, or the arms, legs, and head might flex briefly. These spasms tend to occur in clusters, each lasting only a few seconds. But a series of spasms can last for minutes.
The exact cause of infantile spasms is unclear to parents or doctors. They can be associated with brain malformations, genetic/metabolic conditions, infection, injury, or a lack of oxygen during birth. In some cases, we never know the cause.
Infantile spasms can sometimes be misdiagnosed as colic or as normal startle responses. An electroencephalogram (EEG), which records electrical activity in the brain, is often used to help diagnose the condition. A pattern called hypsarrhythmia is often seen on EEG in children with infantile spasms.
Frequently Asked Questions
Why is my baby so stiff?
Many babies go through short phases of stiffening their arms or legs as part of normal reflexes. This usually passes on its own. The concern is when stiffness is constant, makes movement difficult, or appears alongside other issues such as irritability or developmental delays. as we talk about above, doctors call this hypertonia, which means unusually high muscle tone. Hypertonia itself is not a diagnosis, but it can be a symptom of underlying conditions, including cerebral palsy, Erb’s palsy, and kernicterus (jaundice).
Why does my baby stiffen when held?
If your baby arches their back or stiffens their neck and legs when picked up, it may simply be a startle reflex. But if this reaction happens frequently or makes cuddling uncomfortable, it can, in rare cases of stiff babies, be an early sign of a neurological issue such as cerebral palsy. Babies with CP may also cross or “scissor” their legs when lifted.
Why does my baby have stiff legs and arms?
Brief stiffening is common and not a big deal, but persistent rigidity in the arms and legs is not. When a baby consistently stiffens, scissor-crosses their legs, or resists bending, doctors may investigate for hypertonia or cerebral palsy. A pediatrician can help determine whether stiffness is a developmental issue or a sign of something more serious.
Do babies outgrow stiffness?
Yes, many infants who stiffen their arms or legs occasionally will grow out of it as their nervous system matures. What matters is whether the stiffness goes away with time or becomes more pronounced. If stiffness continues beyond the newborn stage or interferes with feeding, holding, or play, medical evaluation is important.
How can I tell if my child has cerebral palsy?
Muscle stiffness alone does not prove cerebral palsy, but in babies under six months, it can be one of the first signs. Over time, CP typically presents as clear delays in milestones such as rolling, crawling, or sitting. A neurologist can confirm the diagnosis through physical exams and imaging.
What is the treatment for hypertonia?
Treatment depends on the cause and severity. For some babies, early physical and occupational therapy makes a big difference. Doctors may also recommend oral medications such as baclofen or benzodiazepines, targeted treatments like botulinum toxin injections, or, in rare cases, surgery to lengthen tendons. Early intervention is key because therapy can improve comfort, mobility, and long-term development.
Any hypertonia treatment plan begins with therapeutic exercise to improve the range of motion. Therapeutic exercise encompasses a range of treatment techniques designed to decrease or inhibit muscle tone. There is also some evidence to support the benefits of music therapy.
Many medications improve spasticity. These include baclofen, benzodiazepines, dantrolene, clonidine, and tizanidine. Intrathecal baclofen (ITB) therapy has been shown to reduce spasticity and improve general functioning.
Surgery is also an option in some cases to improve function and appearance. The surgical procedure often involves tendon lengthening or transfer.
Recent Medical Studies
Below are some recent medical studies on hypertonia/stiff babies.
- What is new on the horizon in neonatology? by Ramel et al., Frontiers in Pediatrics, 2025. This editorial reviews recent innovations in neonatal care, including new insights into neurodevelopmental outcomes in infants with tone abnormalities. The article underscores advances in early detection methods and emerging therapeutic approaches aimed at reducing long-term disability associated with conditions such as hypertonia.
- Neonatal Tone Management by Mercuri et al., Seminars in Fetal and Neonatal Medicine, 2024. This review discusses the challenges of diagnosing and managing abnormal tone in newborns, particularly distinguishing between hypertonia and hypotonia in early infancy. The authors emphasize the role of advanced neuroimaging and standardized neurological assessments in improving early recognition of tone abnormalities. They also highlight the importance of early intervention strategies to optimize developmental outcomes.
- Rehabilitation management: Hypertonia by Christopher Joseph, Current Problems in Pediatric and Adolescent Health Care, 2022. It provides an overview of the clinical definition and management of hypertonia, focusing on its impact on patients with leukodystrophy. The article highlights the prevalence of hypertonia among children with leukodystrophy and the associated symptoms, such as spasticity, muscle tightness, and posture issues. It emphasizes the importance of managing hypertonia in improving patients’ quality of life and function. The management recommendations are based on evidence-based practice, clinical experience, and patient/family values.
- Patterns of atypical muscle tone in the general infant population – Prevalence and associations with perinatal risk and neurodevelopmental status, by E.J Straathof, Early Human Development, 2021. In a study examining atypical muscle tone in infants from the general Dutch population, about 8% displayed impaired muscle tone in three or four body parts, while 50% had atypical tone in one or two body parts. The most common patterns were isolated hypotonia in the legs and isolated hypertonia in the arms. Notably, isolated hypertonia in the arms was linked to perinatal risks. The “impaired pattern” of atypical tone in three or four body parts was associated with preterm births and an increased risk of developmental disorders. So while many infants show atypical muscle tone, certain patterns can indicate a higher risk and necessitate further medical evaluation.
- Case study on the use of intensive pediatric neurorehabilitation in the treatment of kernicterus by Jessie Mann et al., Journal of Clinical Movement Disorders, 2020. Kernicterus, a result of untreated jaundice, is one condition that causes hypertonia. This case study looks at one instance of a boy with kernicterus and how his condition was treated. A treatment plan for this condition may include occupational, speech, and physical therapy. The boy in this case study was also treated with stem cell therapy. Researchers found he had success with an intensive, four hours per day for three weeks of therapy.
- Spinal Hyper-Excitability and Altered Muscle Structure Contribute to Muscle Hypertonia in Newborns After Antenatal Hypoxia-Ischemia in a Rabbit Cerebral Palsy Model by Sylvia Synoweic et al., Frontiers in Neurology, 2019. The researchers in this study wanted to understand better what causes high muscle tone in newborn babies after they experience oxygen deprivation. The researchers tested numerous mechanisms in rabbits. They found that changes to the passive properties of muscles primarily explain muscle resistance to stretching. In other words, while you might expect that damage to the nerves and their ability to communicate would be the most critical factor in explaining hypertonia, the passive mechanics of muscles, such as their elasticity, are just as important, if not more so.
- Management of hypertonia in cerebral palsy by Nickolas Nahm et al., Current Opinion in Pediatrics, 2018. This article is a review of the treatments available to treat hypertonia. Though these treatments are specific to cerebral palsy patients, many apply to other children and adults who suffer from hypertonia. These treatments include botulinum toxin (Botox) injections, baclofen, and rhizotomy surgery. According to the authors, the best course of treatment depends on the patient and their goals.
- “Neonatal hypertonia–a diagnostic challenge” by Anthony Hart et al., Developmental Medicine & Child Neurology, 2014. This study is one of the most comprehensive overviews of the diagnosis of newborn hypertonia. The authors present a diagnostic approach in the form of a flow chart to help healthcare providers in the complicated process of diagnosing this condition. Diagnosis is based on family history, medical history, and current symptoms. For each possible diagnosis, the authors diagram the corresponding age of onset, symptoms, and what to test for.
Contact Miller & Zois About Birth Injuries
If you believe your baby was injured during birth, you and your child may be entitled to financial compensation from the healthcare providers or hospital that handled the delivery. If your child has a lifelong injury, this money can change the quality of life that your child will have.
Calling a lawyer may also allow you to find out what really happened to your child. At Miller & Zois, our birth injury and cerebral palsy lawyers have many years of experience handling these cases. Call the birth injury lawyers at Miller & Zois at 800-553-8082 or get a free online consultation.