A 40-year-old man was arrested after he brought a 12-year-old girl to hospital, saying she was three months pregnant and needed a routine check-up.
The man initially claimed his "wife" was 20 years old and said she needed a standard test to make sure her unborn child was healthy.
The pair were accompanied on the trip to Xuzhou City Central Hospital, in East China's Jiangsu province, by another woman, claiming to be the girl's mother-in-law.
Doctors who tried to question the girl were unable to get a response, as she did not speak any Mandarin, according to The Mirror.
The "husband" and "mother-in-law" said the wife was 20 years old, but medics immediately alerted local authorities when they found the young patient to be of schoolgirl age.
One of the staff said: "It's obvious she is just a child, and certainly not anywhere near 20 years old."
The man became angry and refused to answer their questions, reportedly saying: "I took her here to be examined - just do your job. Stop asking so many questions."
Police officers discovered the girl did not possess a Chinese ID and concluded that she was a foreign national from Southeast Asia, but her exact origins are still unclear.
Investigators suspect that she was abducted or bought as a foreign bride - the Chinese have a history of purchasing Vietnamese brides from across the country's southern border.
The legal age of marriage in China is 20 for women and 22 for men. However many rural families will allow their children to marry as young as 13, and then simply register the marriage later when the children have reached the legal age.
Liu Neng, a sociology professor from Peking University, told the Daily Mail that getting married at this age is a cultural norm for youngsters in rural areas who have not much else to do once they reach puberty.