Cerebral palsy is the most common motor disability in childhood, yet many families receive a diagnosis without a clear explanation of why it happened. According to the CDC, approximately 1 in 345 children in the United States has been identified with cerebral palsy. For parents navigating a new or recent diagnosis, understanding what causes cerebral palsy often feels urgent and necessary.
The honest answer is that there isn’t always one clear cause. Cerebral palsy results from damage to or abnormal development of the brain during a critical period of growth. That damage can happen in more than one way. What unites every case is that something disrupted the brain’s ability to properly control movement and muscle tone, whether that disruption happened before birth, during delivery, or in the first years of life.
This article breaks down what researchers know about the causes of CP, which risk factors matter most, and what parents can do with that information as they move forward with care.
How Cerebral Palsy Develops in the Brain
The brain is central to every cerebral palsy diagnosis. To understand what causes cerebral palsy, it helps to first understand how the developing brain works and why it is so vulnerable during pregnancy and the early newborn period.
The Critical Window of Brain Development
Brain development begins in the first few weeks after conception and continues rapidly through early childhood. During this time, billions of neurons form and migrate to specific locations. They also begin building the connections that control movement, speech, and learning. The systems responsible for motor control—including the motor cortex, cerebellum, and basal ganglia—are especially active during this window. They are also particularly sensitive to disruption.
Any injury or abnormality during this period can affect how motor systems develop. This includes issues like infection, reduced blood flow, or irregular gene expression. The earlier the disruption occurs, the more broadly it tends to affect brain function and development.
Why Brain Injuries in Early Life Have Lasting Effects
Damage to the developing brain doesn’t repair itself the way a broken bone does. Injured areas may stop forming correctly, and surrounding regions compensate, sometimes imperfectly. This is what makes cerebral palsy a permanent condition. However, its effects on movement can shift as a child grows and the brain continues to mature.
Cerebral palsy is the leading cause of childhood disability in the United States. It is not a single disease but a group of conditions, all rooted in this same developmental disruption. The location and extent of the brain injury determine the types of cerebral palsy a child is diagnosed with and which areas of function are most affected.
The Main Causes of Cerebral Palsy
Understanding what causes cerebral palsy means looking across three broad timeframes: before birth, around the time of delivery, and in early childhood. Most cases fall into the first two. The CDC reports that congenital cerebral palsy, meaning CP linked to events before or during birth, accounts for 85% to 90% of all diagnoses.
Causes Before Birth
Prenatal causes are the most common source of cerebral palsy. The developing brain can be affected by a range of disruptions during pregnancy, including:
- Infections during pregnancy: Viruses such as cytomegalovirus (CMV), as well as infections like rubella and toxoplasmosis, can cross the placenta and interfere with brain development during key developmental stages.
- Reduced blood flow to the fetus: When blood flow is disrupted for any reason, including placental problems or complications of high blood pressure, the developing brain may not receive adequate oxygen or nutrients during critical growth periods.
- Fetal stroke: A blood clot or bleeding in the brain before birth can damage motor pathways before a baby ever leaves the womb.
- Genetic and structural abnormalities: Mutations in specific genes or chromosomal differences can cause abnormal brain development, even in the absence of external injury.
- Maternal health conditions: Thyroid disorders, uncontrolled infections, and certain medications used during pregnancy have been associated with an elevated risk for cerebral palsy.
Causes Around Birth and in Early Childhood
The delivery process and the first years of life are also periods of real vulnerability. When something goes wrong during or shortly after birth, the consequences for the developing brain can be significant. Here are the most common causes in this window:
- Oxygen deprivation at birth: When a baby is deprived of oxygen during labor or delivery, the brain can sustain widespread damage. This is called hypoxic-ischemic encephalopathy (HIE).
- Premature birth: Babies born before 32 weeks of gestation have brains still forming outside the womb. They face a higher risk of bleeding in the brain and white matter damage, both of which are strongly associated with cerebral palsy.
- Low birth weight: Babies weighing less than 3 pounds 5 ounces at birth have a significantly elevated risk of CP, even independent of how early they were born.
- Severe jaundice: Untreated severe jaundice can lead to kernicterus, a form of brain damage that primarily affects movement and hearing.
- Infection in early infancy: Meningitis and encephalitis in the first months of life can cause direct brain damage, leading to what doctors call acquired cerebral palsy.
Risk Factors Parents Should Know
Knowing what causes cerebral palsy is different from knowing who is at higher risk. A risk factor raises the chances of CP but does not guarantee it. Most children exposed to these factors do not develop the condition. Still, understanding them matters because it shapes how closely a child should be monitored in the early years.
Medical and Pregnancy-Related Risk Factors
Several conditions during pregnancy have been consistently linked to higher cerebral palsy rates. Multiple pregnancies, including twins and triplets, carry an elevated risk, particularly when complications arise. Blood type incompatibility between mother and baby can cause severe jaundice if not identified and treated quickly. Thyroid problems, seizure disorders, or infections in the mother during pregnancy also appear in the research as factors that slightly increase risk.
Exposure to certain toxins and environmental factors during pregnancy continues to be studied. Research has linked prenatal exposure to air pollution with elevated CP risk in some populations. This adds another layer to an already complex picture.
Birth Complications and Newborn Health Factors
Certain events and conditions after birth signal the need for early and close developmental monitoring. Babies who require resuscitation at delivery should be evaluated carefully and consistently. The same is true for those who score poorly on newborn assessments or have had seizures in the first days of life. In each case, early monitoring is critical.
Similarly, premature infants—especially those born before 28 weeks—require close follow-up. They are often monitored with brain imaging to detect white matter injury. This type of injury is most closely associated with spastic diplegia, a form of CP that primarily affects the legs.
Newborn infections, prolonged severe jaundice, and confirmed brain bleeds all signal the need for close monitoring. In these cases, families and pediatricians should stay proactive about tracking developmental milestones. Early identification consistently leads to earlier intervention, which in turn leads to better outcomes for children with CP.
When cerebral palsy is confirmed, understanding the cause can help guide what to look for next. Conditions like cerebral palsy and autism frequently occur together, and the same prenatal events that cause CP can sometimes affect other developmental systems. A thorough evaluation covers the full picture, not just movement and muscle tone. As a child grows, understanding the nature of their brain injury also informs decisions about therapy, bracing, and whether cerebral palsy surgery might improve mobility and quality of life.
Located in Tampa, Florida, Children’s Cerebral Palsy serves families throughout the Tampa Bay area and across Florida. Dr. Siambanes and his team provide comprehensive evaluations and individualized treatment plans for children at every stage of diagnosis and care. Contact us to schedule a consultation and take the next step toward understanding your child’s condition.
