Video: Study: Obesity contributes to early puberty

  1. Closed captioning of: Study: Obesity contributes to early puberty

    >>> good evening. i'm ann curry in for brian williams tonight.

    >>> as a new study published today reveals stunning and alarming findings about the health of our daughters. according to the study of more than 1,200 children, a significant number of girls are showing signs of puberty as young as 7 years old. with the findings the researchers are raising concerns that our girls will be at greater risk for behavioral problems, perhaps breast cancer in the future. in a moment we'll talk to a leading pediatrician about what parents can do. we begin now with nbc's rehema ellis.

    >> reporter: the results are startling. more than 1,200 girls between the ages of 7 and 8 from new york, cincinnati and the san francisco bay area were part of the study. the findings reported in today's journal of pediatrics revealed that while the average age of the onset of puberty is 10 or 11, 15% of the girls showed signs of puberty at 7 years old. among them, 10% of white girls , twice as many as in a 1997 study, but 15% of hispanic girls and 23% of african- american girls .

    >> early development is a risk factor for disease including breast cancer , cardiovascular disease and diabetes.

    >> reporter: doctors worry that children are not emotionally prepared for puberty at such a young age. no one knows the exact cause of early puberty in girls . theories range from exposure to chemicals in plastics, hormones in food, declining physical activity and the epidemic rise in childhood obesity.

    >> so if that's the case, you have to make sure your children are eating whole diets, exercising regularly and that their weight gain is not too fast.

    >> reporter: and there are other concerns.

    >> puberty can be normal in some girls -- early on set of puberty, but it can be a sign of serious disease.

    >> reporter: this mother of two isn't ready.

    >> no, i don't think so. i don't think emotionally that they are ready to go through the changes that your body goes through. it's just scary to young children.

    >> reporter: young children showing signs of adulthood much too soon. rehema

By contributor
updated 8/9/2010 7:41:13 PM ET 2010-08-09T23:41:13

The changes in Kiera’s body scared her parents. Though the 8-year-old seemed her usual chipper self, she’d started to develop headaches and acne. More alarming to her mom, Sharon, were the budding breasts on Kiera’s thin little chest.

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“I thought, she’s too young,” remembers the Pittsburgh mom. “She’s still fearful about sleeping by herself. An 8-year-old just isn’t mature enough to handle this.”

For Kiera, whose last name is being withheld to protect her privacy, it was all so embarrassing. None of her friends seemed to be experiencing what she was. When they asked about the acne and her expanding chest, Kiera was evasive. “I didn’t want to tell them what was going on,” says the Pittsburgh girl, now age 9. “So I had to kind of lie to them.”

When Kiera’s parents took their daughter to the doctor, he assured them that nothing was wrong with the girl. Kiera was simply starting puberty early.

As it turns out, puberty at age 7 or 8 isn’t so unusual these days. A new study, published Monday in the journal Pediatrics, shows that more American girls are maturing earlier and earlier. Typically, U.S. girls hit puberty around age 10 or 11.

Exactly what this shift means for girls isn’t clear yet — either on a group or individual level.  But there are budding concerns. For instance, studies have linked an early start to menstruation with an elevated risk of breast cancer. And other research has shown that girls who go through puberty early tend to have lower self-esteem and a poor body image. They are also more likely to engage in risky behaviors which can result in unplanned pregnancies, experts say.

The possible link to breast cancer was what sparked the new study. To take a long-term look at the impact of puberty and other factors on breast cancer, researchers enrolled 1,239 girls between the ages of 6 and 8 from three sites in the U.S.: New York’s East Harlem, the greater Cincinnati metropolitan area and the San Francisco Bay area.

The study revealed a surprisingly large bump in the number of girls going through puberty between the ages of 7 and 8. For example, the researches found that 10 percent of 7-year-old white girls had some breast development as compared to 5 percent in a study published in 1997. Similarly, 23 percent of the 7-year-old black girls had started puberty as compared to 15 percent in the 1997 study.

Nobody’s sure what is driving the declining age of puberty. But the rise in obesity could be at least partly to blame, says the study’s lead author, Dr. Frank Biro, director of adolescent medicine at Cincinnati Children’s Hospital.

That makes a lot of sense to Dr. Luigi Garibaldi, a professor of pediatrics and clinical director of pediatric endocrinology at Children’s Hospital of Pittsburgh at the University of Pittsburgh Medical Center.

Back in the 1700s, girls didn’t start to menstruate till they were 17 or 18, Garibaldi says. That had a lot to do with malnutrition. The assumption is that the steady decline in age since then has to do with more abundant food.

There may be other environmental factors at work, too, says Dr. Stanley Korenman, an endocrinologist at the University of California, Los Angeles.

For example, Korenman says, environmental exposure to estrogens in plastics, chemicals and foods has been going up. “And estrogens do stimulate breast development,” he adds.

Until we know what the cause is, the best way to slow puberty may be to “start living green,” says Biro. “It may help for families eat together and to consume well-balanced diets. Regular physical activity may help, too.”

Another finding from the study may back that concept up. The rate of early puberty was much lower in the San Francisco group: 7 percent among white 7-year-olds from northern California versus 14 percent among Ohioans of the same age. Among black 7-year olds, 27 percent of Californians hit puberty early as compared to 31 percent of the New Yorkers. Northern California’s temperate climate fosters more outdoor activities and the emphasis on healthy foods results in a better diet.

Why all the fuss about early puberty?

Beyond the possible breast cancer connection, there’s also the issue of emotional maturity, Biro says. “Just because a girl has matured physically, doesn’t mean she’s socially or psychologically mature,” he explains.

There’s also the issue of stature. There are some studies, Biro says, that show that kids who mature early don’t grow as tall.

As part of her work-up, Kiera had a bone exam. Doctors concluded that at age 8 she had the bone development of a 10 year old, which meant her growth might be stunted.

For Kiera and her family, the answer was simple: slow puberty down. She now has an implant placed under the skin of her upper arm that doles out regular doses of a drug that blocks the spiking hormones that were taking her into early sexual maturity.

Kiera was happy to see her breasts stop budding and to once again feel like she fits in with all her friends. These days she says she’d be perfectly happy if those breasts didn’t start to swell again till she was 16.

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