My colleague's son, who until recently still liked her colorful locks, now scolds her: "Mom, can't you just look normal!". At the latest, when children start to feel embarrassed because of their parents, there is no longer any doubt - they are in puberty.
During this period, the body produces a much larger amount of sex hormones: estrogen and gestagen in girls, testosterone in boys. These hormones cause a number of changes, and mood swings are normal - including distancing from parents.
Today, puberty starts almost a year earlier than half a century ago
All this happens earlier today than before. The results of a study published in the Journal of the American Medical Association show that in 2013, puberty in girls began on average a year earlier than in 1977. The situation is similar for boys, but the conclusions in the study are not so clear.
As for the first menstruation, no significant changes have been found here - since the 1960s in Europe it has occurred on average at the age of 13. But in the 19th century this only happened at the age of 17. The "earlier" of the first menstruation today can be explained by the fact that, thanks to the improved standard of living, today's girls are physically prepared enough to give birth to children at an earlier age, explains German pediatrician Bettina Golke to DW. "However, in girls, puberty does not begin with the first menstruation, but with the growth of breasts," she emphasizes. But why has this moment shifted forward by a whole year in just five decades? The reasons are various and not all of them can be clearly proven.
Does weight have an impact?
It has been established that overweight children enter puberty earlier. Their fat tissues produce a larger amount of the hormone leptin, which signals the brain to begin puberty.
The fact that today's children move less and often gain excess weight may be one of the reasons why during the pandemic many more girls have entered the so-called precocious puberty. In this case, the external sexual characteristics develop in girls before they are nine years old, and in boys before they are ten.
"Added to this is the fact that the whole lifestyle changed at that time, which burdened children psychosocially: they spent much more time in front of the computer, and blue light - as animal studies have shown - affects hormones," explains Golke. According to her observations, the incidence of precocious puberty has meanwhile decreased again.
What is the impact of chemicals on puberty?
Scientists suggest that environmental chemicals also have an impact on puberty. For example, it has been shown that the insecticide DDT leads to earlier menstruation. Certain substances in body cosmetics - such as phthalates, parabens and other phenols - are also suspected of causing earlier puberty. This is especially true for girls.
It is not excluded that plasticizers in plastics may also have an effect, says Golke - it is simply that the global trend towards an increasingly earlier onset of puberty has developed in such a short period of time that it cannot be explained by any genetic changes.
Unfortunately, however, it is not possible to say which substances are to blame - there are over 100 different substances that can accelerate precocious puberty, as animal studies have shown. In addition, the amount matters - a dose that is harmless to animals can have an impact on children.
Lavender and soy affect hormonal balance
Essential oils can also affect hormones. For example, if lavender products are used, breasts grow earlier (in both girls and boys). Laboratory studies have shown that 65 essential oils have a hormonal effect on human cells. In all children studied, breast growth slowed down after they stopped using perfumed products.
Soy products also have a hormonal effect. Soy contains so-called phytoestrogens - plant substances similar to the human hormone estrogen. The same applies, by the way, to beer.
So far, there is no unequivocal evidence that soy products affect the onset of puberty. But women who were fed soy protein as infants reported in a study that their periods lasted longer and had more pain during their periods. That's why the German Society for Pediatric and Adolescent Medicine does not recommend that infants be fed soy-based products.
Children without siblings enter puberty earlier
Another factor seems to contribute to the earlier onset of puberty - it affects children who do not have siblings more often, a study in Denmark has found. One explanation: when passing on family genes, children without siblings have no one to rely on, and therefore their bodies develop reproductive abilities earlier.
Author: Jeanette Zwink