Police are investigating after the newborn was found completely naked next to a bridge in the Sichuan Province.
She was rushed to the Nanxi Hospital of Traditional Chinese Medicine, where she has since been nursed back to health.
They said they tracked the girl down and that she had been ‘left behind’ by her parents who are working in a neighbouring city.
On the day the newborn was discovered, the grandmother said her granddaughter had been feeling unwell and she decided to take her to hospital for a check-up.
Halfway there, however, the girl claimed she needed to use the toilet and then disappeared behind some bushes by the bridge ‘for 30 minutes’.
It is during this time that investigators believe the child was born and then abandoned. When she returned, they continued to the hospital for her check-up, the grandmother’s statement said.
The grandmother told the police that she ‘had no idea’ that the child was pregnant or that she had mothered a baby girl.
Doctors said the baby appeared to have been born prematurely and was extremely weak when she arrived, however she had no physical deformities or other birth defects that they could see.
The authorities did not comment on whether they were sceptical of the grandmother’s statement.
The police said the girl is refusing to speak to investigators and has therefore not revealed who the father of the child might be.
Individuals in China who have intercourse with minors under the age of 14 can be found guilty of statutory rape, reports said.
The newborn is now being cared for around the clock by volunteer hospital workers.
Members of the public have also donated money and other items such as blankets and baby formula to the hospital.