Athena Skeeter, 40, was arraigned Sunday on charges of manslaughter and endangering the welfare of a child.
The city's Administration for Children's Services did not immediately respond to a message seeking information on Skeeter, whom police said was a licensed child care worker.
According to a court document, Skeeter told police she had been wrestling Friday with 20-month-old Cardell Williamson at her Bronx home after his father dropped him off that morning. She said the child was on the bed when she lifted him by one arm and one leg and put him on the floor. She told police she stepped on his stomach but "didn't use full force."
Skeeter said she then put her son on top of Cardell and stepped on his stomach.
"Cardell acted different after that," Skeeter said, according to the court document. "He threw up. His head kept tilting."
She said she put him in a bathtub and put cold water on his face, and then stepped out for a short time. When she came back, Streeter told police, Cardell's head was in the water and steam was coming up. She said he had burns on his arm and face.
Police responding to a 911 call found Cardell lying on a bed, struggling to breathe. He was pronounced dead at a hospital.
The medical examiner ruled his death a homicide.
Skeeter was in custody and was due back in court Thursday. No attorney information was available for her.