What Causes Cerebral Palsy?

Cerebral palsy is the result of a combination of events either before, during or after birth that can lead to an injury in a baby’s developing brain.

There is no single cause of cerebral palsy. For most babies born with cerebral palsy, the cause remains unknown. Researchers now know that only a very small percentage of cases of cerebral palsy are due to complications at birth (e.g. asphyxia or lack of oxygen). Today, it is accepted that cerebral palsy usually arises from a series of causal pathways, i.e. a sequence of events that when combined can cause or accelerate injury to the developing brain.

For example: Although prematurity is the largest risk factor for cerebral palsy, it is the sequence of events (causal pathways) that led to the premature birth that may have caused the cerebral palsy, rather than the premature birth itself.

In 13 out of 14 cases of cerebral palsy in Australia, the brain injury leading to cerebral palsy occurs either in the uterus (while the mother is pregnant) or before 1 month of age.

Stroke is the most common cause in babies who acquire cerebral palsy after 1 month of age. The stroke may occur spontaneously or arise from surgical or heart complications.

Risk factors

Risk factors do not cause cerebral palsy. However, the presence of some risk factors may lead to an increased chance of a child being born with cerebral palsy.

Some risk factors for cerebral palsy have been identified. These include:
  • premature birth (less than 37 weeks)
  • low birth weight (small for gestational age)
  • blood clotting problems (thrombophilia)
  • an inability of the placenta to provide the developing feotus with oxygen and nutrients
  • RH or A-B-O blood type incompatibility between mother and baby
  • infection of the mother with German measles or other viral diseases in early pregnancy
  • bacterial infection of the mother, foetus or baby that directly or indirectly attacks the infant's central nervous system
  • prolonged loss of oxygen during the pregnancy or birthing process, or severe jaundice shortly after birth.

Who is at greatest risk?

It has been identified that four groups, statistically, have a greater risk of cerebral palsy.
  1. Males - Males are at greater risk of having cerebral palsy
  2. Premature babies - Prematurity is associated with higher rates of cerebral palsy
  3. Small babies - Low birth weight is associated with higher rates of cerebral palsy. This may be a result of prematurity or slow intrauterine growth. Around 42% of children with cerebral palsy had low birth weight, compared to just over 6% of the Australian population
  4. Twins, triplets and higher multiple births. 11% of children with cerebral palsy were from a multiple birth, whereas the rates of multiple births are only 1.7% in the Australian population.

Is cerebral palsy genetic/hereditary?

Familial cerebral palsy is uncommon, approximately 1% of people with cerebral palsy will have a sibling with the condition. It is even uncommon in twins - when one twin has cerebral palsy, 90% of co-twins will not have cerebral palsy. However small these statistics, they are enough to suggest that there might be some genetic factors involved in cerebral palsy. Researchers generally believe that a genetic disposition to certain characteristics, i.e. prematurity or heart problems, may start a chain of events (causal pathways) that can result in a child having cerebral palsy.
(Update: Nov 17 2015)