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Many of us natural-minded mamas have already been aware of the rise of puberty starting earlier and earlier in girls (and boys, but not as dramatically) and we've already worked on limiting factors that may contribute to that. Researchers are finally taking a more serious note, looking into factors like obesity and chemical exposure to be the backstory.


In the mid-90s, Dr. Marcia Hermen Giddens began to gather data on 17,000 girls, looking specifically at the age of puberty onset. She's a public health expert at the University of North Carolina, and her research showed the average age of puberty was dropping to ten years old, with some girls starting puberty as early as six-years-old.

At the time of the study, Dr. Hermen-Giddens was serving as the director of a child abuse team at Duke University in North Carolina. She noticed that many of the children who'd been abused were developing breasts as young as six or seven years old. Drastically different than the typical puberty onset in early teens.

In an article with The New York Times, she said that something didn't seem right. There wasn't any data for her to investigate and that's what spurred her to gather her own. Her research found that on average, young black girls began the onset of puberty a year earlier than their peers and she didn't understand why. Experts in the field initially believed obesity was a major risk factor, but Dr. Anders Jul believed there was more. Dr. Juul is a pediatric endocrinologist at the University of Copenhagen and he's published a handful of studies on the phenomenon of early puberty.

When Dr. Hermen-Giddens's work came out, he believed obesity to be the major factor in that the U.S. has significantly higher obesity rates than girls do in his country. Additionally, there was no decrease in the age of onset puberty in girls in his country like there was in the U.S.

But over a decade later, when Dr. Juul noticed an increase in the number of referrals for early puberty in Copenhagen, he began to believe differently. He saw girls who were developing breasts at seven or eight years old and a 2009 study showed that the average age of breast development in school-aged girls of Copenhagen had dropped by a year since his first study on the issue that didn't show those numbers just a year before.

More curiously, girls were getting their periods earlier, around 13-years-old, than they were just a few months before. Obviously, he found that to be a significant change in a short time period. He didn't believe it to be obesity, though, as the body mass index of the children he studied was not any different in 2009 than it was in the 1990s. Obesity was not his go-to risk factor. Instead, he believed chemical exposure is to blame.

His 2009 study found that girls with the earliest breast development had the highest urine levels of phthalates--substances used to make plastics more durable and that are found in everything from vinyl flooring to food packaging.

Phthalates are considered to be 'endocrine disruptors' as they're believed to affect the behavior of hormones that may lead to puberty. Evidence is considered 'weak' but as researchers keep digging, they find more and more connections, if not causality. Last month, Dr. Juul and a team of researchers looked at hundreds of studies on endocrine disrupters and their effects on puberty. The analysis included 23 studies that were similar enough to compare, but it was unable to show a clear association between any individual chemical and the age of puberty. Dr. Juul says we don't know the cause, but we should keep exploring the chemical exposure relationship.

Others still believe there are multiple factors involved, at least for early onset puberty in girls. There is a case to be made for sexual abuse in early childhood as a link with earlier puberty onset, but Dr. Hermen-Giddens also hypothesized that girls who have developed earlier than peers might be more vulnerable to abuse so it could be a chicken or egg situation.

Research has suggested that girls who are more likely to reach puberty may have mothers with a history of mood disorders, and girls who do not live with their biological fathers may also be at risk for earlier puberty. Additionally, the pandemic has had parents at home more with their kids, so maybe they're just noticing things more and submitting referrals for early-onset puberty.

It's definitely a trend experts across the world see, and warn about as girls who begin puberty earlier may be at an increased risk of developing different types of cancer, or from suffering from mental health issues like anxiety or depression.

The good news is that it's finally being recognized as a 'thing' and maybe more research will now be available to show us how to protect our kids and let them be kids for as long as they're meant to be.