Li Zhenghua, 24, was found by medics trying to eat her child while in a hospital ward in Shenzhen, southern China, recovering from the birth.
The woman is believed to have been living on the street after being thrown out by her mother-in-law despite being pregnant.
She was reportedly surviving on the streets for a number of weeks before being found and taken to hospital.
Luckily a nurse discovered the woman with her teeth locked around her son and raised the alarm.
The nurse, named as Liu Tianlun, attempted to prise the woman off the baby but the mother refused to let her child go.
A hospital spokesman said the doctor injected something that eventually loosened the mother’s jaw.
The spokesman added: “It was really shocking, the arm was badly damaged and suffered not only heavy bruising but bleeding as a result of the bite.
“Fortunately, doctors managed to insert something to stop her closing her teeth and then levered her jaws apart.
“After that they gave her a sedative and took the baby to a secure location.”
Hospital staff are deciding whether to give the newborn back to his mother.
An investigation into the incident is on-going.