Judge Thomas Parisi also sentenced Petitjean to 3 1/2 years of probation.
Petitjean had pleaded guilty to endangering the welfare of a child, saying she had "hit rock bottom." She had thrown her 4-year-old son onto the tracks and then jumped into the Schuylkill River in Exeter Township on May 19.
The crew of a freight train spotted the pair. The boy was not struck by the train, and Petitjean was rescued by firefighters using a boat.
