Brett Smith for redOrbit.com – Your Universe Online
Sometimes it seems like today’s children are growing up faster than ever, and a new study published in the journal Pediatrics has found that American girls are indeed entering puberty earlier than ever before. The study also found a strong connection between female childhood obesity and the early onset of puberty.
“The impact of earlier maturation in girls has important clinical implications involving psychosocial and biologic outcomes,” said Dr. Frank Biro, author of the new study and a physician at Cincinnati Children’s Hospital Medical Center. “The current study suggests clinicians may need to redefine the ages for both early and late maturation in girls.”
Girls that physically mature faster than others run higher risks of having lower self-esteem, higher rates of depression, engaging in disruptive behavior, and lower academic performance. The early onset of puberty is also related to greater risks of obesity, cardiovascular problems and several types of cancer.
In the study, researchers in the San Francisco Bay Area, Cincinnati and New York City tracked more than 1,200 girls ranging in age from 6 to 8 years at enrollment for the onset of breast development based on the five-stage scale known as the Tanner Breast Stages. In addition to tracking the girls’ physical maturity, the research team also recorded participants’ ethnicity and body mass index (BMI).
Female participants were followed at regular intervals from 2004 to 2011 and tracked longitudinally, which involved multiple regular visits for each girl. The researchers said this method gave a good perspective of the progress of each girl and when specific events in a girl’s life took place.
The team found that the onset of breast development varied by race, BMI and geographic location. Breast maturity started in white, non-Hispanic girls at a median age of 9.7 years, considerably earlier than previous studies had found. African-American girls experienced breast development at a median age of 8.8 years, earlier than white girls and consistent with previous studies. The median age for Hispanic girls’ development in the study was 9.3 years, and 9.7 years for girls of Asian descent.
Higher BMI was also related to earlier development. According to the research team’s report, rising obesity rates appear to be a “prime driver” for earlier breast development.
“The girls who are obese are clearly maturing earlier,” Biro told NBC News. “BMI is, we found, the biggest single factor for the onset of puberty.”
The researchers found that, on average, girls with BMIs below the 50th percentile experienced breast development at about age 10, while girls in the 85th and 95th percentiles began the maturation process as early as 8.5 years old.
Some experts say extra weight may ‘fool’ a young girls’ body into believing it has enough energy and other resources to start physically maturing – even at an earlier age.
Biro was careful to point out that BMI is just one of a host of factors that could be causing these girls to start puberty early and said parents shouldn’t focus on their child’s weight in order to delay puberty.
“Parents of these early maturing kids have to be more watchful,” he said. “But I don’t want to have a nation of patients with eating disorders. We need to figure out what are healthy weights for our kids. We want them to be comfortable with their bodies.”
A 2012 study by researchers from the University of North Carolina’s School of Public Health also found that boys were hitting puberty earlier as well – an average of six to 24 months ahead of what is considered healthy by medical professionals.
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