Most cerebral palsy traces back to something that happened before birth — an infection that crossed the placenta, a stretch of low oxygen, a structural problem with the brain, or a genetic vulnerability that shaped how the brain developed. Understanding what can go wrong during pregnancy is the foundation for prevention.
When families ask what caused their child’s cerebral palsy, the answer is usually traced to something that happened during pregnancy — not, as people often assume, only during labor and delivery. According to the broader picture of CP causes, around 85–90% of cases are congenital, meaning the brain injury happened before or around the time of birth. The prenatal period accounts for the bulk of those.
This page is the umbrella view of what can go wrong before birth: how the fetal brain develops, what disrupts that development, and how prenatal care reduces the risk. For deeper dives on the specific causes, we’ll point you to the dedicated guides as we go.
The fetal brain follows a precise developmental schedule. Neurons form, migrate to their proper positions, and wire up into circuits over a period of months. Anything that disrupts that schedule — structural problems, restricted blood flow, or abnormal growth patterns — can lead to the kind of brain injury that produces cerebral palsy.
The disruptions don’t need to be dramatic to matter. Mild, sustained problems — reduced oxygen delivery from a poorly functioning placenta, low-grade inflammation from an unrecognized infection, or growth restriction from maternal hypertension — can shape brain development over weeks. The cumulative effect is what shows up later as CP.
The patterns most often seen on brain imaging in children with CP whose injuries originated prenatally:
For families, knowing the specific pattern matters because it can clarify cause and inform treatment choices. Some patterns point clearly to the timing of the injury; others remain ambiguous.
Some indicators of fetal brain injury can be detected during pregnancy with the right monitoring:
Not every prenatal injury shows up on these tests, and not every concerning finding indicates CP — but consistent prenatal care creates the chance to catch problems early when intervention can still help.
The standard 20-week anatomy scan is the single most informative routine prenatal test. It can identify:
The fetal brain doesn’t develop all at once — different regions form at different times, with different vulnerabilities. The motor cortex, cerebellum, and basal ganglia — the regions whose injury produces CP — mostly take shape between 8 and 20 weeks. Disruption during this window has the biggest effect. That’s why first-trimester prenatal care, infection screening, and avoiding teratogens (substances that cause birth defects) matter so much.
Recent research has established that genes contribute to a meaningful share of CP cases — possibly up to 25% — usually working with environmental factors rather than alone. Genetic predisposition can affect how the brain develops or how vulnerable it is to other prenatal stresses.
Genetic contributions to CP rarely follow simple inheritance patterns. More often, multiple genes each contribute small effects, or a new mutation appears spontaneously in the egg, sperm, or early embryo. Some genes affect brain structure directly. Others affect how the developing brain responds to stress — making it more or less able to tolerate brief oxygen deprivation, maternal infection, or premature birth.
The genes most commonly involved in CP affect:
Some of these genetic conditions can be detected with prenatal genetic testing, especially if there’s a family history. For a fuller walkthrough, see our deeper guide on genetic factors in cerebral palsy — including which mutations have been identified, how genetic testing works, and what a finding can mean for treatment and family planning.
Some infections cross the placenta and reach the fetus directly. Others trigger maternal inflammation that affects the developing brain even when the pathogen itself never crosses. Both pathways can lead to CP, and both are largely preventable with screening, vaccination, and prompt treatment.
The infections that most often contribute to CP are grouped clinically as TORCH infections — toxoplasmosis, other (syphilis, varicella, parvovirus, Zika), rubella, cytomegalovirus, and herpes simplex. Cytomegalovirus (CMV) is the most common congenital infection in the U.S., affecting about 1 in 200 newborns, and it’s a leading infectious cause of CP. Others, like rubella, have been nearly eliminated by routine vaccination — a reminder that prevention works.
The mechanism is usually inflammatory. When the mother’s immune system mounts a response — even to an infection that doesn’t cross to the fetus — chemical signals can reach the placenta and trigger fetal inflammation. The developing brain is particularly sensitive to inflammation; sustained or repeated exposure can disrupt how neurons develop their connections.
For the deeper picture of which infections matter most, how they’re screened for, and what prevention looks like, see our dedicated guide on cerebral palsy and maternal infections.
Some events labeled as “birth complications” actually start during pregnancy. Cord problems, placental abnormalities, and growth restriction develop in the prenatal period but produce their effects during labor and delivery — which is why prevention starts in pregnancy, not just on the delivery date.
Examples of complications that bridge prenatal and perinatal periods:
The cord is the baby’s lifeline. Problems with it — cord prolapse during labor, nuchal cords (wrapped around the neck), true knots, or compression — can rapidly cut off oxygen. Some cord problems are detected on prenatal ultrasound; others appear suddenly during labor.
Advanced maternal age (typically defined as 35 and older) is associated with elevated risks of gestational diabetes, hypertension, chromosomal abnormalities, and preeclampsia — all of which can contribute to CP risk. Younger maternal age (under 18) is also associated with elevated risk, partly due to nutrition and prenatal-care access. Risk is manageable at any age with proper monitoring.
For the full breakdown of what can go wrong during labor and delivery itself — and how medical mistakes during this window contribute to CP — see our guide on birth complications leading to cerebral palsy.
If your prenatal care providers missed signs of growth restriction, placental dysfunction, or maternal infection — and your child was later diagnosed with CP — that may rise to medical malpractice. Common errors include failure to order or correctly interpret ultrasounds, missing signs of preeclampsia, and inadequate infection screening. Our birth injury lawyers offer free record reviews. Request a free case review.
Our nurse advocates can help you understand what your prenatal records show and what additional testing might clarify. Get a free, confidential evaluation — no commitment, just direction.
Prenatal causes include genetic mutations, maternal infections (CMV, rubella, toxoplasmosis), placental insufficiency that limits oxygen and nutrients, prenatal stroke, structural brain malformations, exposure to toxins or certain medications, and maternal health conditions like preeclampsia or diabetes. Most CP cases trace to a combination of these factors rather than a single cause.
Conditions like uncontrolled diabetes, hypertension, preeclampsia, thyroid disorders, and chronic infections can disrupt placental function and fetal development. They reduce oxygen and nutrient delivery to the fetus, trigger inflammation, or directly impair brain growth. Good prenatal management of these conditions substantially reduces the risk of CP.
Studies have linked exposure to fine particulate matter (PM 2.5) and other air pollutants during pregnancy to increased CP risk. The pollutants can trigger systemic inflammation in the mother and oxidative stress that crosses the placenta, affecting the developing fetal brain — especially during critical growth windows.
The fetal brain is most vulnerable during the first trimester (when major brain structures form) and early second trimester (when neurons migrate to their final positions). Disruptions during these windows — from infection, oxygen deprivation, or toxin exposure — can have lifelong effects. The third trimester is also vulnerable, particularly to oxygen deprivation and stroke.
Early prenatal care lets doctors identify and manage risk factors before they become problems. That includes infection screening, blood pressure monitoring, gestational diabetes testing, and detailed ultrasounds that can spot fetal growth issues. Starting prenatal care in the first trimester gives the most benefit.
Genetic predisposition contributes by either causing CP directly through specific mutations or by making the developing brain more vulnerable to environmental insults. A child with genetic susceptibility may develop CP from a relatively minor perinatal event that wouldn’t harm a child without that predisposition. For more on this, see our guide on genetic factors in cerebral palsy.
Kelsey is an experienced surgical nurse with more than 10 years in hospital-based care, including leadership within the operating room. She has worked extensively with pediatric patients, refining her ability to support children and families during critical moments. As both a mentor and patient advocate, Kelsey is dedicated to promoting safety, communication, and compassionate care while helping families understand medical procedures, treatment options, and the realities surrounding birth injuries and pediatric conditions.
Our nurses, patient advocates and legal experts are solely focused on bringing you the latest cerebral palsy information, options for financial assistance and access to community support.
Editorial process →