A recent survey conducted by the Fudan University and the Shanghai Children's Hospital found about 1 percent of the children in Shanghai are afflicted with early puberty. Doctors have observed a rapid increase in such cases in the past few years, with girls being affected more than boys.

The survey found early puberty had become the second largest endocrine disease of Shanghai children, next to obesity.

A third of the visitors to the pediatric endocrine departments of Shanghai Children's Hospital, Xinhua Hospital and Ruijin Hospital consulted or sought treatment for early puberty.

"I met a patient, an 8-year-old girl, who is 1.18 meters tall," said doctor Yin Qi from Shanghai's Jiangao Clinic, a branch of Capital Institute of Pediatrics in Beijing. "Her bone age was 10 years old. She won't be able to grow to 1.5 meters without medical intervention."

If a girl shows development of secondary sex characters at the age of 8, and a boy at 9, doctors consider it a case of early puberty. Usually, children with early puberty won't be able to grow to normal height because their epiphysis, the growth area near the end of a bone, closes earlier than it should, stopping bones from growing.

Doctors from major hospitals said 52.5 percent of the children shorter than normal suffer from depression. Also, the early outbreak of sexual impulse may lead to sex-related crimes or teenage pregnancy, Yin said.

Early puberty is caused by many reasons, Yin said. "You are bombarded with sexual scenes on TV now. Such scenes stimulate children too and triggers hormone secretion."

Such hormones are often found in fast food, which accelerate children's development. "The problem is more serious in major cities than in the countryside because urban children are better fed."