Cerebral palsy is caused by a problem with the brain that happens before, during or soon after birth.
The brain can either being damaged or not develop normally, although the exact cause is not always clear.
Problems before birth
Cerebral palsy is usually caused by a problem that affects the development of a baby's brain while it's growing in the womb.
These include:
damage to part of the brain called white matter, possibly as a result of a reduced blood or oxygen supply – this is known as periventricular leukomalacia (PVL)
an infection caught by the mother – such as cytomegalovirus, rubella, chickenpox or toxoplasmosis
a stroke – where there's bleeding in the baby's brain or the blood supply to their brain is cut off
an injury to the unborn baby's head
Problems during or after birth
Cerebral palsy can also sometimes be caused by damage to a baby's brain during or shortly after birth.
For example, it can be due to:
the brain temporarily not getting enough oxygen (asphyxiation) during a difficult birth
an infection of the brain, such as meningitis
a serious head injury
choking or nearly drowning, resulting in the brain not getting enough oxygen
a very low blood sugar level
a stroke
Increased risk
Some things can increase a baby's risk of being born with cerebral palsy including:
being born prematurely (before the 37th week of pregnancy) – babies born at 32 weeks or earlier are at a particularly high risk
having a low birthweight
being part of a multiple birth, such as a twin or triplet
the mother smoking, drinking a lot of alcohol, or taking drugs such as cocaine, during pregnancy