Lauren Buzard was arrested Thursday after being caught on camera smearing her son's feces on his face at Children's Hospital of Pittsburgh, WPXI-TV, Pittsburgh reported.
Investigators said the hospital placed surveillance cameras were placed in Buzard's son's room after the child was brought to the hospital several times.
Buzard was seen on camera digging through a hamper of dirty linens, wiping the pad of a diaper, then smearing something on her son's face.
The mother allegedly told doctors that her son had vomited.
Buzard was being held in county jail and is scheduled to appear before a judge on Wednesday.