What Causes Cerebral Palsy: Risk Factors, Triggers and What You Can Change

A father in a physical therapy waiting room once told me he had replayed the night of his son’s birth so many times he could recite the fetal heart monitor readings. He was sure the answer was in there somewhere. Months later, a brain scan pointed to something that had happened weeks before labor, when nobody was watching a monitor at all.

That gap between where families look and where the evidence points is the story of cerebral palsy. The condition affects roughly 1 in 345 children in the United States, making it the most common motor disability of childhood, yet the question of what actually causes it is answered more often by rumor than by data.

This article walks through what mainstream evidence does and does not say: when the brain injury tends to occur, which risk factors carry real weight, which ones are myths and, honestly, which small pieces of the picture anyone can influence.

Is cerebral palsy one disease or several?

Cerebral palsy is not a single illness with a single cause. The name is an umbrella term for a group of permanent movement and posture disorders that share one feature: they stem from a disturbance in the developing brain, either before birth or in early childhood. The word cerebral points to the brain; palsy refers to weakness or trouble controlling muscles.

Two children can carry the same diagnosis and look very different. One may have stiff, tight muscles on one side of the body, the classic pattern of spastic hemiplegia. Another may have unsteady, writhing movements or poor balance. Some walk independently; others use wheelchairs. The type and severity depend on which regions of the brain were affected, how large the area was and at what stage of development the injury occurred.

The clinical picture also changes over time even though the underlying brain change does not. A newborn with damage to the motor cortex may look almost typical for the first months, because babies do little voluntary movement at that age. The stiffness and asymmetry emerge as the nervous system matures and the missing connections are asked to do more. That is why the National Institute of Neurological Disorders and Stroke describes cerebral palsy as non-progressive: the brain injury itself is fixed, but its effects unfold with growth.

Keeping this framing in mind helps make sense of the causes. We are really asking what can interrupt brain development during a narrow, vulnerable window, and the answer is: many different things, acting through a handful of shared mechanisms such as oxygen shortage, bleeding, infection and inflammation.

When does the brain injury actually happen?

Timing matters more than almost anything else in this conversation, because the popular assumption gets it backward. The Centers for Disease Control and Prevention reports that 85 to 90 percent of cerebral palsy is congenital, meaning the brain damage occurred before or during birth. In most of those cases the responsible event took place during pregnancy, not in the delivery room.

The remaining cases are described as acquired: brain injury more than 28 days after birth, from causes such as infection, head trauma or a stroke in infancy or early childhood. The CDC notes this is a small percentage of the total.

Here is how the timing and the typical mechanisms line up, drawn from CDC and NHS summaries.

Timing	Common mechanisms	Examples
During pregnancy	Interrupted brain development, infection, reduced blood flow	Maternal infections, placental problems, fetal stroke, genetic changes
Around labor and birth	Severe oxygen shortage, birth trauma	Placental separation, cord complications, very difficult delivery
Newborn period	Bleeding, jaundice, infection	Brain hemorrhage in preterm infants, kernicterus, meningitis
After 28 days	Acquired injury	Head injury, near-drowning, stroke, severe infection

The practical takeaway is uncomfortable but freeing: for most families, the cause lies in a period they could neither see nor control. Understanding the true timeline is often the first step in setting down the guilt that so many parents describe.

Does a difficult birth usually cause cerebral palsy?

For much of the twentieth century, doctors and families alike believed that cerebral palsy was mainly the result of a baby being deprived of oxygen during labor. It was a tidy explanation. It was also largely wrong.

The NHS now states plainly that a lack of oxygen during birth, once thought to be the main cause, is responsible for only a small number of cases. Large population studies from several countries found that the rate of cerebral palsy did not fall as electronic fetal monitoring and cesarean delivery became widespread, which is not what you would expect if birth asphyxia were the dominant driver.

This does not mean birth complications are irrelevant. A severe, prolonged shortage of oxygen, sometimes called hypoxic-ischemic injury, can damage the deep structures of the brain that coordinate movement. Events such as the placenta separating early, the umbilical cord becoming compressed or a uterine rupture can produce that kind of emergency. When it happens, the injury pattern on later imaging tends to be recognizable, and the baby is usually visibly unwell in the first hours and days of life.

The distinction that matters is between an acute catastrophic event and an ordinary hard labor. Long labors, forceps deliveries and low Apgar scores at one minute are common; cerebral palsy is not. Most babies who have a rough entrance into the world recover fully. Conversely, many children with cerebral palsy had uneventful deliveries and a cause that was invisible until a scan revealed it.

If a family suspects a birth-related injury, a neonatologist or pediatric neurologist can review the medical record and imaging together. That review, rather than replaying memories, is where honest answers tend to come from.

Why is premature birth the single biggest risk factor?

If you were to name one factor that consistently raises the likelihood of cerebral palsy, it would be being born too early. The CDC lists preterm birth, meaning before 37 weeks, as a leading risk factor, with the risk rising sharply for babies born before 32 weeks. Low birth weight travels alongside it: infants weighing under 5.5 pounds are at increased risk, and those under 3 pounds 5 ounces face the highest risk of all.

The reason is anatomical. Between roughly 24 and 34 weeks of gestation, the brain’s white matter, the wiring that carries signals from the motor cortex down to the spinal cord, is still forming. The blood vessels that supply it are fragile and the region sits close to the ventricles, the fluid-filled spaces inside the brain. Two things can go wrong in this delicate stretch of development.

The first is bleeding. Tiny vessels near the ventricles can rupture when a preterm baby’s blood pressure swings, and a larger bleed can damage the neighboring motor pathways. The second is a pattern of injury called periventricular leukomalacia, in which patches of white matter soften and die after periods of low oxygen or inflammation. Because the fibers controlling the legs run closest to the ventricles, this injury classically produces spastic diplegia, with the legs more affected than the arms.

Modern neonatal care has dramatically improved survival for very preterm infants, and the proportion who develop cerebral palsy has fallen over recent decades in high-income countries. Still, prematurity remains the reason many children carry the diagnosis, and it is why the most meaningful prevention efforts focus on healthy pregnancies rather than on the delivery itself.

Which infections during pregnancy are linked to cerebral palsy?

An infection in a pregnant person does not have to reach the fetus to affect the fetal brain. The inflammatory chemicals the immune system releases, called cytokines, can cross the placenta and disturb developing tissue on their own. This is one of the more important shifts in how researchers think about cerebral palsy: inflammation, not only direct infection or oxygen loss, appears to be a recurring pathway.

Certain infections are more strongly associated than others. The CDC and Mayo Clinic name several:

• Rubella, a viral illness that can cause a wide range of birth defects when acquired in early pregnancy.
• Cytomegalovirus, a common virus that usually causes mild or no symptoms in adults but can damage the fetal brain and hearing.
• Toxoplasmosis, a parasitic infection spread through undercooked meat and contaminated soil or cat litter.
• Herpes simplex and syphilis, both of which can be passed to the baby.
• Zika virus, which is linked to abnormal brain development.
• Chorioamnionitis, an infection of the membranes and fluid surrounding the fetus, which raises the risk of preterm labor as well.

Fever in the mother during pregnancy has itself been associated with a modest increase in risk in some studies, though the evidence is not strong enough to say fever alone causes cerebral palsy. What is clearer is that prompt attention to infections, and sensible precautions such as safe food handling and hand hygiene, reduce exposure.

Infections after birth count too. Meningitis and severe bloodstream infections in a newborn can inflame and injure brain tissue, and these are among the recognized causes of acquired cerebral palsy. The common thread is that a developing brain tolerates inflammation poorly, whichever direction it arrives from.

Can placental problems or twin pregnancies play a role?

The placenta is the fetus’s lung, kidney and delivery service rolled into one organ, and when it underperforms, the brain is among the first tissues to feel the shortfall. Conditions in which the placenta does not implant well, becomes infected or separates from the uterine wall before delivery can reduce oxygen and nutrient flow for hours or weeks. Chronic, low-grade insufficiency may be part of why some babies are born small for their gestational age, itself a risk marker.

Multiple pregnancies carry a separate set of risks. The CDC lists twins, triplets and higher-order multiples among the recognized risk factors for cerebral palsy. Part of the reason is simple arithmetic: multiples are far more likely to be born preterm and at low birth weight. Part is specific to sharing a womb. Twins who share a placenta can develop unequal blood flow between them, and if one twin dies during pregnancy, the surviving twin faces a higher risk of brain injury.

Assisted reproductive technology appears on risk lists as well, though the interpretation needs care. The CDC notes that the increased risk seen after infertility treatment is thought to be largely explained by the higher rates of multiple births and prematurity that come with it, rather than by the treatment acting directly on the fetal brain. As single-embryo transfer has become more common, that gap has narrowed.

Rh incompatibility, in which a mother’s immune system attacks the baby’s red blood cells, was once a significant cause of severe newborn jaundice and brain damage. Routine prenatal screening and preventive care have made it rare in countries with organized maternity services, a quiet public health success that rarely gets mentioned.

Is cerebral palsy genetic?

Cerebral palsy is not inherited in the way that, say, cystic fibrosis is passed from parent to child by a single faulty gene. Most children with the condition have no family history of it, and most parents of a child with cerebral palsy will not have another affected child. That said, genetics is a bigger part of the story than doctors believed even a decade ago.

Two lines of evidence have shifted the picture. First, some children diagnosed with cerebral palsy, particularly those born at full term with no obvious risk factors and no clear injury on brain imaging, turn out on genetic testing to have changes in genes involved in brain development or in the function of nerve cells. Second, certain gene variants seem to make a developing brain more vulnerable to stressors such as low oxygen or inflammation, so that an event one baby shrugs off leaves lasting damage in another.

The NIH and Mayo Clinic both now list genetic changes among recognized contributors, while emphasizing that the proportion of cases with a purely genetic cause is uncertain and still being studied. It is fair to describe genetics as a contributing factor in a minority of children rather than a common single cause.

Why does this matter for families? A confirmed genetic diagnosis can end years of unanswered questions, clarify whether future pregnancies carry any increased risk and, in a few conditions that mimic cerebral palsy, point toward a different management approach entirely. When a child’s history does not fit the usual pattern, asking a pediatric neurologist whether genetic evaluation is appropriate is a reasonable question, not an overreach.

Can jaundice, stroke or a brain bleed in a newborn cause it?

Some of the most important causes of cerebral palsy happen in the first days and weeks after birth, when a baby is home and looks, to most eyes, perfectly well.

Newborn jaundice is a case in point. More than half of babies develop some yellowing of the skin in the first week as their liver learns to clear bilirubin, a breakdown product of red blood cells. In the vast majority this is harmless and fades. If bilirubin climbs very high and goes untreated, however, it can deposit in the deep brain structures that fine-tune movement, causing a condition called kernicterus. The CDC identifies kernicterus as a cause of cerebral palsy, and it is one of the few that is almost entirely preventable with monitoring and timely treatment.

Stroke sounds like a disease of older adults, but it can occur in a fetus or newborn. A clot or bleed cuts off blood to one part of the brain, and because the damage is on one side, the result is often spastic hemiplegia, with an arm and leg on the opposite side affected. Perinatal stroke is among the more common identifiable causes in babies born at term, according to the NIH. Clotting disorders in the baby or mother, heart defects and infections can all contribute.

Bleeding into or around the ventricles, as described earlier, is largely a hazard of prematurity. The vessels of a full-term newborn are sturdier, though trauma or a bleeding disorder can still produce a hemorrhage.

What links these three is that they are events rather than long processes, and imaging often shows their footprint clearly. That clarity can be painful, but it also gives families a real answer instead of a shrug.

What causes acquired cerebral palsy after birth?

The developing brain does not become sturdy at birth. It stays vulnerable through infancy and early childhood, and injuries during that time can produce a movement disorder indistinguishable from congenital cerebral palsy. Clinicians use the term acquired cerebral palsy when the damage occurs more than 28 days after birth, and the CDC lists three main categories.

Infection comes first. Bacterial meningitis, an infection of the membranes covering the brain and spinal cord, and viral encephalitis, an infection of the brain tissue itself, can leave permanent damage even when a child survives and recovers from the acute illness. The younger the child, the greater the risk of lasting effects.

Injury is the second category. Motor vehicle crashes, falls, child abuse and near-drowning can all cause the kind of severe head trauma or oxygen deprivation that damages motor areas. This is the one group of causes where ordinary safety measures, correctly installed car seats, window guards, pool fencing and never leaving a young child unattended near water, directly reduce risk.

Problems with blood flow round out the list. A stroke in infancy, whether from a clotting problem, a heart condition or sickle cell disease, can injure the motor pathways. Blood vessel malformations that rupture fall into this group as well.

Acquired cases are a small slice of the total, but they carry a particular weight for families because the cause is usually known and datable. The clinical approach is the same as for congenital cerebral palsy: early recognition of motor difficulties, thorough assessment and support tailored to the child’s actual abilities rather than to the label.

Which maternal health conditions raise the risk?

A parent’s health before and during pregnancy shapes the environment in which a brain is built. Several conditions appear repeatedly in the evidence, though it is worth stressing at the outset that the great majority of babies born to people with these conditions do not develop cerebral palsy. Risk factors shift odds; they do not decide outcomes.

The CDC and Mayo Clinic note associations with thyroid disorders, seizure disorders and intellectual disability in the mother. Thyroid hormone is essential for fetal brain development in the first half of pregnancy, when the fetus depends on the mother’s supply, so an untreated underactive thyroid can have downstream effects. Seizure disorders are linked partly through the seizures themselves and partly through the complex medical management they require, which is a matter for the treating clinician to weigh with each patient.

High blood pressure disorders of pregnancy, including preeclampsia, affect placental blood flow and are a common reason for early delivery. Diabetes that is poorly controlled before and during pregnancy is associated with a range of complications that indirectly raise risk. Exposure to certain toxic substances, including alcohol and tobacco, appears on most lists because of its broader harm to fetal development.

What all of this argues for is unglamorous: consistent prenatal care, starting before conception when possible. Managing chronic conditions with a clinician, treating infections promptly and keeping blood pressure and blood sugar in range are the levers that actually exist. None guarantees anything. Collectively they represent the best available way to lower the background risk, and the evidence for them is far stronger than for any single intervention marketed as protection.

Did I do something to cause my child's cerebral palsy?

This is the question almost every parent asks, usually silently, and it deserves a direct answer grounded in what the evidence actually shows.

For the overwhelming majority of families, the answer is no. The most common causes, prematurity, developmental disruptions in early pregnancy, placental problems, fetal stroke and genetic changes, are not brought about by anything a parent did or failed to do. Many of them occur before a pregnancy is even confirmed. The NHS is explicit that in many cases the exact cause is never found, and the absence of an identifiable trigger is itself a common finding rather than a sign that something was missed.

Guilt tends to attach to the things people can remember: a stressful week, a glass of wine before the pregnancy was known, a fall, a long labor. Everyday stress has not been shown to cause cerebral palsy. Minor falls almost never injure a fetus cushioned by amniotic fluid. Ordinary hard labor, as discussed, is not the cause in most cases. Where the evidence does show a link, as with heavy alcohol use or untreated infection, the mechanism runs through broad effects on fetal development, and even then risk is raised, not certainty created.

Doctors who work with these families often say that the most useful thing they can offer after a diagnosis is a careful review of the timeline: when the injury most likely occurred, what the imaging shows and what that rules out. Parents who receive that explanation frequently describe relief, not because the news is good, but because it replaces a story of blame with a story of biology. If no one has walked you through it, asking your child’s neurologist to do so is entirely reasonable.

What can you actually change to lower the risk?

Honesty requires saying that most cerebral palsy cannot be prevented with current knowledge. There is no test that reliably predicts it and no single action that rules it out. Yet a handful of measures, each backed by mainstream evidence, do lower the odds of the events that cause it. They are worth naming precisely because they are so ordinary.

Before pregnancy, the highest-value steps concern the parent’s own health. Working with a clinician to bring chronic conditions such as thyroid disease, diabetes, high blood pressure or a seizure disorder under good control creates a steadier environment for early brain development. Checking that protection against infections such as rubella is current, and discussing any needed follow-up, falls into this same planning conversation.

During pregnancy, regular prenatal visits allow problems with blood pressure, growth or the placenta to be caught early, and they are the setting in which infections get diagnosed and treated. Food safety habits reduce toxoplasmosis and listeria exposure: cooking meat thoroughly, washing produce, avoiding unpasteurized products and letting someone else handle cat litter. Avoiding alcohol, tobacco and recreational substances removes known developmental hazards. Where a pregnancy is at high risk of very early delivery, obstetric teams have evidence-based protocols intended to protect the preterm brain; those decisions belong with the treating team.

After birth, two areas stand out. The first is jaundice: attending newborn checks and seeking care promptly if a baby looks increasingly yellow, is very sleepy or feeds poorly, because kernicterus is preventable. The second is injury prevention through infancy and early childhood: rear-facing car seats installed correctly, safe sleep, pool fencing, never shaking a baby and supervising around water. None of this is exciting. All of it is real.

How do doctors work out the cause once cerebral palsy is diagnosed?

Finding the cause and confirming the diagnosis are two separate tasks, and they often unfold over months rather than days. Cerebral palsy is diagnosed from the way a child moves, not from a scan, which is why the NHS notes that it is usually recognized between the ages of one and two, though signs may be noticed earlier, particularly in babies known to be at high risk.

Once a movement disorder is evident, the search for a cause typically starts with a detailed history: the pregnancy, the delivery, the newborn period and the family. Was the baby preterm? Was there a known infection, jaundice or a stay in intensive care? Did motor milestones lag from the start, or was there a period of normal development followed by a change, which might point toward an acquired cause?

Brain imaging, usually magnetic resonance imaging, is the central tool. Different injuries leave different signatures: white matter loss around the ventricles suggests an event during the preterm window; a wedge-shaped area of damage on one side points to a stroke; deep gray matter changes may indicate severe oxygen shortage or kernicterus; a malformed brain structure suggests a disruption very early in pregnancy. Imaging is normal in a minority of children, which is one of the situations in which genetic testing becomes more valuable.

Blood tests may look for clotting disorders, infections or metabolic conditions, some of which can mimic cerebral palsy and require different management. Hearing and vision assessments are routine because the same injuries often affect those systems.

Even after a thorough workup, some families are left without a definite answer. That outcome is common and does not reflect inadequate care. The purpose of the investigation is not only to name a cause but to rule out conditions that need specific attention and to give families the fullest picture the evidence allows.

When should you see a doctor about a baby's movement?

Because cerebral palsy is diagnosed by observing how a child moves, parents and caregivers are often the first to notice that something is different. Trusting that instinct matters. Early assessment does not change the underlying brain injury, but it does connect a child with support during the period when the developing nervous system is most adaptable.

The NHS, Mayo Clinic and CDC describe a similar set of early signs worth raising with a pediatrician:

• A baby who feels unusually stiff or unusually floppy when held, or whose body seems to arch away.
• Persistent use of one side of the body, such as reaching only with one hand, especially before 12 months.
• Delays in head control, rolling, sitting or crawling well beyond the typical range.
• Difficulty feeding or swallowing, or excessive drooling that continues past infancy.
• Walking on tiptoes, with a scissoring gait, or with legs held stiffly once walking begins.
• Tremors, jerky movements or movements that seem uncontrolled.

Seek care urgently, the same day, if a newborn’s skin or the whites of the eyes are becoming more deeply yellow, if a baby is very drowsy and hard to wake, refuses feeds, has a high-pitched cry or arches backward, has a fever or a bulging soft spot, or has any seizure-like episode. Head injury with vomiting, unusual sleepiness or loss of consciousness at any age is an emergency. These red flags do not mean cerebral palsy is present; they signal conditions such as severe jaundice, infection or brain injury that need prompt treatment in their own right.

For the more gradual concerns, the message is simpler. Motor milestones vary widely among healthy children, and most delays turn out to be nothing. A pediatrician can tell the difference between normal variation and a pattern that warrants referral, and a child who is checked and found to be developing typically has lost nothing by being seen.

Frequently asked questions

What is the most common cause of cerebral palsy?

There is no single most common cause, but premature birth and its consequences, particularly bleeding or white matter injury in the developing brain, account for a large share of cases. The CDC lists preterm birth and low birth weight as the leading risk factors. In babies born at term, perinatal stroke, infections during pregnancy and disruptions in early brain development are among the more frequently identified causes.

Is cerebral palsy caused by the mother?

In the vast majority of cases, no. The main causes, such as prematurity, early developmental disruption, placental problems, fetal stroke and genetic changes, are not the result of anything a parent did. Certain maternal health conditions and exposures can modestly raise risk, which is why prenatal care matters, but risk factors shift probabilities rather than cause the condition, and many cases have no identifiable trigger at all.

Can cerebral palsy be detected during pregnancy?

Not reliably. Routine prenatal scans can sometimes reveal a brain malformation, a stroke or a significant bleed, and those findings may prompt closer follow-up after birth. Most of the brain changes that lead to cerebral palsy are not visible before delivery, and there is no prenatal test that predicts the condition. Diagnosis rests on observing a child’s movement and posture, typically during the first two years of life.

Does cerebral palsy run in families?

Usually not. Most children with cerebral palsy have no affected relatives, and it is not inherited in the straightforward way that single-gene disorders are. Research does show that genetic changes contribute in a minority of children, and some variants may make a developing brain more vulnerable to stress. If a child’s history does not fit the typical pattern, a pediatric neurologist can advise whether genetic testing would be informative for the family.

Can a difficult labor cause cerebral palsy?

Occasionally, yes, but far less often than people assume. A severe and prolonged shortage of oxygen during birth, for example from the placenta separating early or a serious cord complication, can damage the motor areas of the brain. The NHS notes that such events account for only a small number of cases. An ordinary long or difficult labor, without a catastrophic event, is not a recognized cause.

Can cerebral palsy develop later in childhood?

Cerebral palsy can be acquired after birth if the developing brain is injured in infancy or early childhood. The CDC defines acquired cerebral palsy as damage occurring more than 28 days after birth, from causes such as meningitis, encephalitis, serious head injury, near-drowning or stroke. This represents a small percentage of all cases. Once the brain has matured beyond early childhood, similar injuries are classified differently.

Is cerebral palsy preventable?

Most cases cannot be prevented with current knowledge, because the causes often occur early in pregnancy and are not detectable. Some risk can be lowered through good preconception and prenatal care, prompt treatment of infections, avoiding alcohol and tobacco, monitoring and treating newborn jaundice, and preventing childhood head injuries and drowning. These measures reduce the chance of specific brain injuries but cannot eliminate risk entirely.

Why does premature birth increase the risk of cerebral palsy?

Between roughly 24 and 34 weeks of gestation, the brain’s white matter and the fragile blood vessels around the ventricles are still developing. Swings in blood pressure, low oxygen or inflammation during this window can cause bleeding or a pattern of white matter injury called periventricular leukomalacia. Because the nerve fibers controlling the legs run closest to the affected area, preterm-related cerebral palsy often affects the legs more than the arms.

Can newborn jaundice cause cerebral palsy?

Severe, untreated jaundice can. Very high bilirubin levels may deposit in deep brain structures that regulate movement, causing kernicterus, a recognized cause of cerebral palsy. Mild jaundice, which affects more than half of newborns, is harmless and clears on its own. Routine newborn checks are designed to catch rising bilirubin early, and a baby who looks increasingly yellow, is very sleepy or feeds poorly should be seen promptly.

Do doctors always find the cause of cerebral palsy?

No. Even after a detailed history, brain imaging and sometimes genetic and blood tests, a definite cause is not found in a meaningful proportion of children, and the NHS notes that in many cases the exact cause is never identified. That outcome does not indicate inadequate care. The evaluation still serves to rule out conditions that mimic cerebral palsy and to give families the fullest picture the evidence allows.

References

• NHS – Cerebral palsy: Causes
• NIH National Institute of Neurological Disorders and Stroke – Cerebral Palsy
• MedlinePlus – Cerebral Palsy
• Cleveland Clinic – Cerebral Palsy

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.