12-7-2014
Why are more and more girls experiencing early puberty?
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.
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