Children as young as two can suffer from a disorder which sends them into puberty - but doctors have developed ways to delay it.

Puberty - hormonal changes which ready the body for adulthood and reproduction - can be disastrous when it strikes a young child.

If left to proceed unchecked, it could mean that growth is stunted as the body receives chemical signals telling it to switch off further height gain.

In addition, young children, particularly girls, are unprepared for the associated body changes, and the mood problems which normally affect teenagers.

Irreversible effects

The trouble with treating "precocious puberty" is that the process is governed by the release of body chemicals from the brain.

It is difficult to stop these being released, and their effects are irreversible.

Dr Russell Viner, from Great Ormond Street Children's Hospital in London, told BBC Radio 4: "Babies are born with gonads, but they stay pretty quiescent or turned off until something turns them on at between nine or 10 years old.

"The messages that turn them on come from the brain."

However, US scientists appear to have found an effective way to help these children thrown into adulthood while in primary school.

Strobe light

Professor Bill Crowley, from Harvard Medical School, is helping develop effective drug treatments.

He told BBC Radio 4: "The message from the brain needs to be presented like a strobe light - in an intermittent fashion.

"If one stimulates the system continuously, after a brief spurt of activity, the system shuts down."

So the answer is hormone treatments, given every three months by intramuscular injection, that release a constant stream of chemicals to confuse the body.

These are continued through childhood until the body is truly ready to experience puberty - then discontinued.

"Life as a Teenager" will be transmitted on BBC World Service at 2005 GMT on Monday 1 July.