June 25, 2010
Danish researchers recently released a study of 2095 girls showing they are developing breasts at the age of 9 ½, versus almost 11 about a decade ago. And it can't be blamed on obesity or foods containing hormones.
In fact, the Danish admit, no-one knows why this is happening, particularly in North America. "Conclusions vary from country to country," says the report, headed by Dr. Anders Juul of the University of Copenhagen.
Some studies found "a tendency toward earlier pubertal development in girls 13 to 17" and others don't show this trend, Juul's team noted.
"Timing of puberty follows a familial pattern and, therefore, seems to be controlled by strong genetic factors, although environmental factors also must play a role," the report states.
This includes nutrition, "chronic diseases, migration to a healthy environment (as with foreign adoption), frequent infectious diseases, pollution and exposure to chemicals with endocrine-disrupting properties."
Learning of this study last week, British newspapers got their knickers in several knots, after experts said this trend could apply to British children. And there were cries about the implications for girls' emotional and physical well-being.
"If girls mature early, they run into teenage problems at an early age and they're more prone to diseases later on," Juul told the Telegraph.
Canadian pediatricians' advice? Parents, take a deep breath. This has been going on for years. It's nothing new.
"These trends are measured over decades," says Dr. Jack Holland, a pediatric endocrinologist and professor at McMaster University. "It's not that we are seeing girls going, wham, into puberty. It's been happening over a number of years."
In fact, Dr. Holland has a chart that shows puberty has been arriving earlier and earlier over time. In the late 1800, girls were developing breasts at the ages of 17 and 16. By 1940, it had fallen to 14 ½ and by 1970 it was 12 ½.
Why? No one really knows, says Dr. Holland.
There is a certain amount of hysteria about these developments, he adds, particularly when environmental effects are to blame. The Danish study suggests bisphenol A in cans and baby bottles could be a factor.
Holland believes better nutrition has played a part, and if environmental issues were the real cause behind the changes, boys would be affected too. But they're not — boys go through puberty much later than girls.
Panagiotopoulos, like Holland, doesn't understand why the Danish research "is such a big deal."
Says Holland: "Frankly, as a pediatrician and a father, I am more shocked at the way some mothers dress their kids up as tarts."
Both Canadian doctors say the medical community believes breast development can start at the age of 8; below that is considered unusual.
"No-one knows what causes puberty to happen," says Panagiotopoulos. "I do think obesity certainly does have a big impact."
Neither doctor, however, shrugs off the possibility of environmental changes, but they believe more research must be done since earlier theories like a greater consumption of meat haven't proven to be the answer. Panagiotopoulos says there could be endocrine-disrupting chemicals or soy products, but not enough research has been done to see if this is the case.
Holland recalls a study 25 years ago in Puerto Rico when it was discovered that children were entering puberty earlier, both boys and girls. But it was discovered that the chicken purchased by their parents — consumed in large quantities in this island community — was filled with hormones. Now there are laws about the quantities of estrogen or other hormones that can be given to cattle and other animals that find their way to our plates.
Parents may be worried about earlier maturity of girls for psychological reasons and physical ones — the length of time that estrogen is in the body could have an impact on the development of breast cancer or other cancers later in life.
There may also be fears the development of womanly bodies in 9-year-olds can lead to risky behaviours.
But Holland and Panagiotopoulos say they are noticing no difference in the psychology of girls. They are still behaving as girls were in Grade 4, 20 years ago.
Bottom line: Parents, get a grip. You don't have anything to worry about.