A:Cerebral palsy is usually developed early in life--as early as during pregnancy or later, or a few years after birth. Most cases, about 85% - 95%, occur in utero. Sometimes the specific cause is not known. All cases are due to either abnormal development of the brain or damage to a developing brain. It was once believed that a lack of oxygen to the baby during birth was the most common cause, but now, it is believed to be mostly due to other causes. There are risk factors to developing cerebral palsy, including low birth weight, premature birth, multiple birth, and birth complications.