Police say Kelly Anne Colbridge's blood alcohol content was more than twice the legal limit when she lost control of her car last April.
The vehicle slammed head-on into another car on Street Road in Upper Southampton Township.
Colbridge's 8-year-old son died in the crash.
The couple in the other car was seriously hurt.
Police say Colbridge was also under the influence of prescription pills, at the time of the collision.
A sentencing date has not yet been set.
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