A study in the USA has shown that one in ten Caucasian girls aged seven years old are showing signs of precocious or early puberty, such as breast development, the traditional marker for the onset of puberty, newspaper NZZ am Sonntag reported.

The study also found that the percentage of African-American girls developing breasts at seven years old was 23 percent, with 15 percent of Hispanic girls. Similar findings were reported in the Netherlands, suggesting that many young girls are going through puberty one year earlier than they did during the 1990s, when the average age was recorded as being eight years old.

Despite the fact that eight years old is still considered the normal age for girls to start puberty in Europe, Swiss doctors have also been noticing that they are seeing younger and younger girls, some as young as six years old, starting to develop breasts, newspaper Tribune de Genève reported.

“In my practice, I have many questions about early puberty, and more and more young girls treated for the phenomenon,” Valerie Schwitzgebel, doctor in charge of the Unit of Endocrinology and Diabetology Paediatric University Hospitals of Geneva (HUG), told the newspaper.

Nevertheless, European endocrinologists are hesitant to reduce the normal age to seven because of fears that in some cases early development is linked to brain cancers that would be missed if parents were advised that early development is normal.

The trend in Switzerland is also evident when looking at data from girls in the 1980s, when the average age for the onset of puberty was at 10.9 years old. A British study in the 1960s also found that girls were on average 11 years old as they entered into puberty, NZZ am Sonntag reported.

In the nineteenth century, puberty typically began at the age of 15, Counsel and Heal reported.

The effects of early puberty on a child’s development can be significant. A recent study in Melbourne, Australia, showed a clear link between precocious puberty and the development in later adolescence of depression, online site PsychCentral reported. Other researchers have recorded that low self-esteem associated with early onset can also lead on to other mental problems such as eating disorders.

In order to combat these negative effects, Swiss doctors, such as Franziska Phan-Hug, head of endocrinology at the University of Vaud Central Hospital, prescribe treatment to stop development.

“We do it especially in situations where the offset induces significant suffering or there is a small risk in adulthood of a failure to reach full height,” she told the paper.

Although the precise cause for early onset is unknown, studies have suggested that precocious puberty may be linked to high-fat diets, and to stress in the family environment. Puberty starts earlier in girls who do not grow up with their biological fathers, or live in broken homes, Dr. Richard Sharpe of Edinburgh University recently told the Cheltenham Science Festival, health website Counsel and Heal reported.

Further studies will need to be carried out to assess the exact situation in Switzerland, but in the meantime, studies from other European countries seem to suggest that the trend is certainly prevalent in the Western world.

Denmark, for example, has found that, since 2003, the number of consultations that have taken place that are linked to issues surrounding puberty have increased seven-fold.