The crash occurred less than two miles from the Pittsburgh Monroeville interchange.
The eastbound lanes of the Pennsylvania Turnpike were closed last night near the Monroeville exit until about 5 a.m., police said.
Ms. Baker was pronounced dead at 10:48 p.m. at Forbes Regional. An autopsy is scheduled later today, the Allegheny County medical examiner said.
Her son suffered only minor DUI injuries. He was taken to Forbes Regional, and then flown by helicopter to Children's Hospital.
His condition was not immediately available.
According to county court records, Ms. Baker was arrested twice this year -- in May and June -- on charges of driving under the influence of psychotropic prescription drugs.
She had been free on her own recognizance, pending trial.
