The Ministry of Health has issued its first clinical guideline on the diagnosis and treatment of precocious puberty to ensure that increasing incidents of the condition are properly managed.

The guideline, released late on Friday, follows a scandal widely reported in August about infant girls in Wuhan, capital of Central China's Hubei province, undergoing breast development after being fed milk powder suspected of containing a high concentration of sex hormones.

The ministry dismissed the claims after commissioning its own tests. It has, nevertheless, instructed clinical doctors to improve their understanding of the condition, their ability to diagnose it and to monitor its rate of incidence.

In the newly issued guideline, which is a trial version, precocious puberty is defined as any girl under 8 years old or any boy under the age of 9 who exhibits secondary sexual characteristics, such as enlarged breasts, the onset of menstruation or genital development.

Associated symptoms of the condition, which affects one in 5,000 to 10,000, include the appearance of underarm and pubic hair, rapid growth, advanced bone maturation and behavioral problems, the guideline said.

Investigations conducted by the Ministry of Health found the infant girls in Wuhan, who reportedly exhibited signs of early puberty, had none of the condition's associated symptoms and were therefore not genuine cases, said Wu Xueyan, an endocrine specialist at Peking Union Medical College Hospital.

They were instead undergoing "mini-puberty", which commonly takes place in infant boys up to six months and in girls up to the age of 2, she noted.

Mini-puberty is a surge of the hormones gonadotropins and testosterone in early infancy.

Medical knowledge about mini-puberty is limited, though some experts view it as a normal stage of development.

Internationally, there have been rising cases of early puberty, particularly among girls in recent decades.

A 2010 study by the University of North Carolina at Chapel Hill found that twice as many white girls in the US had undergone early puberty during the ages of 7 to 10 for unknown reasons.

Among the 1,200 girls included in the study, more than 10 percent of them exhibited breast development between the ages of 7 and 10, an incidence rate of 10 percent, whereas a comparable study in 1997 had a 5 percent lower rate of incidence.

The rising number of girls undergoing early puberty has been attributed by some experts to environmental factors like their exposure to chemicals.

However, Wu Xueyan said increased awareness and reporting about the condition have contributed to a rise in the number of cases being diagnosed.