An alleged drug-driver has been charged after a two-year-old child was run over and critically injured in the New South Wales Hunter region.

Jessica Williams had been at a friend's place and was backing her Holden Commodore out of the driveway onto Segenhoe Street, in Woodberry near Maitland about 6.30pm yesterday when she struck the young boy who was playing outside while his father mowed the lawn.

The boy, who is not related to Ms Williams, was taken to John Hunter Hospital and underwent surgery.

He remains in a critical condition.

The driver was arrested at a Woodberry home and taken to Maitland Hospital where she underwent mandatory drug and urine testing.

Police will allege she returned a positive reading for methamphetamine and marijuana.

She has since been charged with dangerous driving occasioning grievous bodily harm, negligent driving, not reverse vehicle safely, and amount of illicit drug in fluid or blood.

Her family told 9NEWS the 22-year-old, who is a mother herself, was not coping.

"She turned around and told her mother to sell the car because she doesn't want to drive anymore, she is absolutely devastated," family friend Ruth Clarke told 9NEWS.

The woman was granted conditional bail to face Maitland Local Court on March 28.

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