A fellow passenger filmed the exchange between the mother, who repeatedly slumps over in her chair, appearing to fall asleep, and her daughter - who repeatedly tries to prop her mother up.
The video went viral after being posted online, with the public calling for the woman featured, who some have suggested was on drugs due to her dozed state, to be tracked down and the safety of the child ensured.
The Department of Human Services in Philadelphia tracked down the family, and then removed the girl - beleived to be 7-years-old - from her mother's care.
On her Facebook page, the mother posted this update: 'I f_ing hope all you skumbags out there are f_ing happy. I just lost the best thing in the world to me all because ppl think before they open there mouths.'
The mother has not been charged with any criminal activity, but according to a police spokesman they are still investigating the situation and have not ruled out making an arrest.
The 26-year-old woman has previous convictions relating to theft, disorderly conduct and promoting prostitution whilst being in prison.