Hate to say this, but Edwards did his homework!
From The Wisconsin Council on Developmental Disabilities about Cerebral Palsy:
CP often originates when oxygen is cut off to the motor cells in an infant's brain. The oxygen deprivation may occur just prior to birth, during a difficult birth, because of prematurity, infection or by a brain injury in the first two years of life. Once the damage is done it can not be changed, but early therapy and/or surgery may increase abilities.
Living and Aging with Cerebral Palsy
The Merck Manual is used in medical training. Their definition says:
Many different types of injury to the brain can cause cerebral palsy, and most often a specific cause cannot be identified. Birth injuries and poor oxygen supply to the brain before, during, and immediately after birth cause 10 to 15% of cases.
From the Cleveland Clinic/causes of Cerebral Palsy:
Lack of oxygen to the baby's during development or delivery