Cerebral palsy (CP) is caused by abnormal development of the brain or damage to the developing brain that affects a child’s ability to control his or her muscles. There are several possible causes of the abnormal development or damage. People used to think that CP was mainly caused by lack of oxygen during the birth process. Now, scientists think that this causes only a small number of CP cases.
The brain damage that leads to CP can happen before birth, during birth, within a month after birth, or during the first years of a child’s life, while the brain is still developing.
CP related to brain damage that happened before or during birth is called congenital CP. The majority of CP (85%–90%) is congenital. In many cases, the specific cause is not known.
Risk Factors for Congenital CP
Some things increase the chance that a child will have CP. These are called risk factors. It is important to remember that having a risk factor does not mean that a child will have CP. Some of the risk factors for congenital CP are:
- Low birthweight―Children who weigh less than 5 1/2 pounds (2,500 grams) at birth, and especially those who weigh less than 3 pounds, 5 ounces (1,500 grams) have a greater chance of having CP.
- Premature birth―Children who were born before the 37th week of pregnancy, especially if they were born before the 32nd week of pregnancy, have a greater chance of having CP. Intensive care for premature infants has improved a lot over the past several decades. Babies born very early are more likely to live now, but many have medical problems that can put them at risk for CP.
- Multiple births―Twins, triplets, and other multiple births have a higher risk for CP, especially if a baby’s twin or triplet dies before birth or shortly after birth. Some, but not all of this increased risk is due to the fact that children born from multiple pregnancies often are born early or with low birthweight, or both.
- Assisted reproductive technology (ART) infertility treatments―Children born from pregnancies resulting from the use of some infertility treatments have a greater chance of having CP. Most of the increased risk is explained by preterm delivery or multiple births, or both; both preterm delivery and multiple births are increased among children conceived with ART infertility treatments.
- Infections during pregnancy―Infections can lead to increases in certain proteins called cytokines that circulate in the brain and blood of the baby during pregnancy. Cytokines cause inflammation, which can lead to brain damage in the baby. Fever in the mother during pregnancy or delivery also can cause this problem. Some types of infection that have been linked with CP include viruses such as chickenpox, rubella (german measles), and cytomegalovirus (CMV), and bacterial infections such as infections of the placenta or fetal membranes, or maternal pelvic infections.
- Jaundice and kernicterus― Jaundice is the yellow color seen in the skin of many newborns. Jaundice happens when a chemical called bilirubin builds up in the baby’s blood. When too much bilirubin builds up in a new baby’s body, the skin and whites of the eyes might look yellow. This yellow coloring is called jaundice. When severe jaundice goes untreated for too long, it can cause a condition called kernicterus. This can cause CP and other conditions. Sometimes, kernicterus results from ABO or Rh blood type difference between the mother and baby. This causes the red blood cells in the baby to break down too fast, resulting in severe jaundice.
- Medical conditions of the mother―Mothers with thyroid problems, intellectual disability, or seizures have a slightly higher risk of having a child with CP.
- Birth complications―Detachment of the placenta, uterine rupture, or problems with the umbilical cord during birth can disrupt oxygen supply to the baby and result in CP.