The age of puberty continues to trend downward as medical experts continue to work out why.
Meanwhile, children who enter puberty early are often given hormonal puberty blockers to halt the process, despite the long-term effects of such medications being unknown.
Early puberty occurs when the pituitary gland and the hypothalamus activate earlier than the norm, “for reasons we don’t know,” said Dr. Jean-Pierre Chanoine, pediatric endocrinologist at the British Columbia Children’s Hospital in Vancouver.
Reproductive organs then start the process of body maturation. The average age, or norm, for puberty’s onset in girls is eight years old, in boys it’s nine. Early onset puberty typically starts at age six or seven, but can in rare circumstances begin even earlier. It is experienced more frequently by girls than boys.
The onset age of puberty has fallen in developed countries since the 1800s, says Chanoine. No one knows why, but there are many theories.
Genetics can be a factor, says Chanoine, who has worked in pediatric endocrinology for more than 25 years. In about half the cases he sees, the mother also experienced puberty early.
Another theory is improved nutrition, at least in developed countries. More caloric intake sparks children’s bodies to start puberty sooner. As the intake of food has increased over centuries, the body mass index — a method of calculating body fat — has grown.
The body needs good nutrition to get through puberty, says Chanoine. During a growth spurt, a child can grow 10 to 30 centimetres while also developing muscle mass. The brain has to consider if the body has “enough calories… enough reserves in the body” for puberty, he said.
Yet another theory under investigation is that endocrine-disrupting chemicals — found in plastic and beauty products — may affect sex hormones in the body that cause early puberty.
The Canadian government has banned one of these chemicals, Bisphenol A or BPA, in baby products. The chemical is still present in other products, such as plastic items and within canned items.
“Endocrine disruptors are present everywhere,” said Dr. Bernard Robaire, who studies endocrine-disruptor chemicals at McGill University. “We all have plastics circulating in our blood.”
Studies at McGill have shown endocrine-disruptor chemicals cause cell lines from the reproductive human organs to “alter their secretion of estrogen and testosterone.”
These chemicals affect estrogen-like action production because estrogen receptors are remarkably sensitive to extremely small doses, says Robaire. These receptors respond to picograms — one-trillionth of a gram.
“If you have a contaminant in your circulation… it can be detected, even at low concentrations,” he said.
However, these association studies — where chemicals are shown to trigger a reaction in animal or cell lines — do not mean the same effects necessarily happen in humans.
‘Still a child’
Chanoine says early puberty can have long-term effects. It can trigger the period to start earlier than normal — around 12.5 years of age in Canada — which can stunt a child’s growth.
“People who do have a very early puberty tend to finish a little bit shorter than their peers,” said Chanoine, who sees about five patients a month with this condition. “They have less time to have their growth spurt. They lose years of development prior to puberty.”’
Noticing their bodies are different from their peers’ can also affect children’s mental health, making them self-conscious and embarrassed by their bodies.
A young girl whose breasts start growing in Grade 3 “is quite different from most of her friends,” said Chanoine.
When girls grow breasts, they may be sexualized by people around them, teased or attract boys’ attention, which are all new experiences for them, says Karen Kaffko, a Toronto-based clinical psychologist.
Parents might notice their child starting to describe themself in negative terms, she says. It’s important parents not add to the child’s anxiety by treating them differently. Sometimes fathers stop hugging their daughters as their bodies change. But Kaffko says it’s important for parents not to stop being affectionate.
“It’s very important to teach parents that even though their child may be developing faster than the next door neighbour, they’re still a child, and they’re still their child,” said Kaffko.
Puberty blockers
If early puberty makes a child very self-conscious, they may be a suitable candidate for treatment with puberty blockers.
“If the young girl has issues with maturity or feels extremely uncomfortable at school, for example, that might be another reason to discuss whether we should stop” puberty with puberty blockers, said Chanoine.
Puberty blockers suppress the production of hormones such as testosterone and estrogen, and are administered by injection every three months, says Chanoine. Children usually continue on puberty blockers until about age 10 or 11. Once they stop the injections, puberty re-starts in a few weeks or months. Generally girls start their period one to three years after starting puberty.
Some girls say, “‘I have two friends in my class who had the first period, so … we can stop’” the puberty blockers, said Chanoine.
Chanoine says puberty blockers have few side-effects. But concerns have grown in the medical community over the drugs’ potential consequences on children. The long-term effects of puberty blockers, first given to children three decades ago, are still being studied.
Often parents will bring their child to a doctor if they see the child’s body start to mature faster than their peers, perhaps when the child begins to grow body hair. That is not a sign of early puberty, just as many signs of body maturation do not mean a child is entering puberty.
The first stage of puberty for boys is the enlargement of the testes, which is often not noticeable, says Chanoine. For girls, the only reliable marker they are entering the first stage of breast development is when their nipples enlarge.
Chanoine says it’s important doctors “try to reassure parents” that starting puberty at eight years old is within the normal range.
“In the vast majority of the patients it is not a medical condition… the development of puberty happens in everybody,” said Chanoine. “It just happens to be present a little bit earlier than it is in the majority of the people.”
