Every once in a while, my children show interest in topics I research for stories. When my older twin found out I was doing a story about early puberty in girls, she panicked.
"No, mommy! You are NOT going to talk about me! Are you?"
"Nah," I assured her.
There's no need to discuss her development, as I've conducted my own general, and highly anecdotal, studies while working as a substitute teacher.
"Wow. Girls look like that in the fifth grade?"
They do in fourth grade, too. In fact, sprouting breast buds at age 8 is within the range of "normal" puberty. "Clinically, less than age 8 would be a concern," explains Dr. Jeanne Hassing, a Spokane pediatric endocrinologist.
Central precocious puberty (CPP) refers to a condition in which very young children's brains start sending puberty-triggering hormones throughout the body much too soon. It occurs 10 times more often in girls than in boys.
"Every hundred years ... even every decade, the age [of central puberty] begins to go down. In the 19th century, it used to be age 16 or 17," says Hassing. For girls, breast growth is the first physical symptom of puberty, and trends earlier with each generation. In 1970, for instance, the average age was 11.5 years. Today's average is 10.5 years.
"I have treated precocious puberty for 30 years," Hassing says. About 10 years ago, however, "the number of girls spiked like crazy."
Precocious puberty requires medical treatment, but it can be difficult to diagnose. Early breast development can sometimes happen in isolation, and without other hormonal changes, most doctors will maintain that a girl isn't going through central puberty.
This tricky fact, along with hundreds of potential lifestyle, health and environmental influences, make pinning down an exact cause of precocious puberty nearly impossible.
"There has always been a difference between girls with higher and lower BMIs [body mass indices], and the correlation between obesity and early puberty is certainly not new," says Hassing. "But the sheer numbers are new," she admits.
"We know that nutrition and the reproductive system are linked," says Dr. Sasha Carey, a Spokane pediatrician who specializes in adolescent medicine. "We see this in anorexics ... you have to have enough body fat to have a period." Carey says scientists assume that when kids aren't at a normal weight — if they're either under- or overnourished — production of the growth hormone leptin is altered. Body fat is estrogenic, and the amount of fat also affects insulin levels, both of which have an impact on the onset of puberty.
"There are so many confounders in this," remarks Carey, who longs for conclusive evidence of why precocious puberty happens. However, "to do a really good study, you have to control for so many factors," such as diet, access to chemicals inside the home and in food and water supplies.
Carey suspects both phthalates, found in soft plastics and cosmetics, and pesticides and hormones in beef and dairy are culprits. "These chemicals are proven to affect cellular processes," she says.
Carey references a case of a 5-year-old girl who had breast budding. "All they could point to was that she'd been using her mother's hair products."
And while the FDA maintains that only safe levels of recombinant Bovine Growth Hormone (rBGH) are used on cattle, neither doctor is convinced. "It also depends on what the animals are being fed. I, myself, only buy organic meats and cage-free, antibiotic-free chicken and beef. I'm suspicious," Carey admits. "But again, there is no hard proof."
Hassing believes a likely culprit is plastic bottles, which contain both phthalates and BPA (bisphenol A), a known estrogen mimicker.
"In about 2004, I saw this dramatic increase... and the correlation to me was seeing all the drinks in plastic. There's a message: 'Don't reuse this plastic bottle,'" Hassing points out. "Why was it OK the first time?" she asks.
The concerns doctors and parents have about CPP are both social and medical. An urgent problem with early puberty is that it kick-starts bone development, before the rest of the young body is ready, and then stops bone development too soon. When puberty ends, height growth stops.
Hassing uses X-rays to check bone maturation and blood tests to detect levels of sex hormones in otherwise immature bodies. The typical treatment involves leuprolide injections, which block the pituitary gland from producing the hormone that triggers estrogen production.
"The main indicator for precocious puberty is being short, but there's more than height at risk," says Hassing. Both she and Carey, as well as parents, worry about the emotional toll of early puberty. "The way people interact with you is different" when you have developed too soon, says Carey. "You look older, so you are potentially treated differently by teachers and coaches."
She says girls and boys weather body changes distinctly. "Boys become more confident as they develop, but girls go the other way. They don't tend to like physical changes, and when those changes happen in a less mature person," the impacts are worse. "There is research that shows they can be victimized, and they get into more dangerous relationships, earlier."
In addition to the social and psychological toll of early puberty, it also can increase the likelihood of estrogen-related diseases like ovarian cysts and breast cancer. While about one in 5,000 children are maturing at too young an age, precocious puberty can be managed with medication. "We want to normalize a child's life and give them an opportunity to not be different," says Hassing. ♦