Doctors and parents were stunned when research published more than a decade ago found some American girls were beginning puberty as early as 7. A new study, released Sunday, suggests the average age at which puberty begins may still be falling for white and Latina girls.
According to the paper, which appears in the journal Pediatrics, almost 25 percent of African American girls have reached the onset of puberty by age 7, now joined by almost 15 percent of Latina girls and more than 10 percent of white girls.
"In 1997, people said, 'That can't be right; there must be something wrong with the study,' " said Dr. Frank M. Biro, director of adolescent medicine at Cincinnati Children's Hospital Medical Center and the lead author of the new study. "But the average age is going down even further."
Biro's study included 1,238 girls ages 6 to 8 who lived in Cincinnati, East Harlem, N.Y., and San Francisco. By age 8, 27 percent of the girls had begun puberty: 18.3 percent of whites, 42.9 percent of blacks and 30.9 percent of Latinas.
There are numerous potential explanations for why puberty is starting earlier. Chief among them is the increase in average body weight among children over the last three decades. Excess body weight, especially body fat, increases the blood levels of estrogens that promote breast development.
Registered nurse Babs Benson, manager of the regional Healthy You program at Children's Hospital of the King's Daughters in Norfolk is not surprised by the research findings. "We definitely see that locally. They are hitting puberty earlier than you'd expect. It's induced by the weight. It's not natural for an 8-year-old to menstruate or have breasts. That's why you're confronted with adult diseases," she says. As to the numbers, Benson observes that statistically black and Latina children suffer from higher rates of obesity than whites. "But the white population is catching up," she says.
At Sentara's Williamsburg Adolescent Center, dedicated to teen medicine, patients are now seen from age 10. "So many begin puberty early, it's the appropriate time to start talking to them," says nurse practitioner Barbara Fallon. She attributes early onset to increasing obesity, and also to the onslaught of sexualized advertising and the amount of phytoestrogens in the environment — in red meat, milk, microwaved Styrofoam, and more.
Biro said that his study would continue to follow the girls' development to look at biomarkers that reflect potential environmental exposures.
Early development in girls is not inconsequential. "It's obviously not good from a medical standpoint," says Benson. "It's also a psychological thing, an emotional problem." Her colleague John Harrington, director of general academic pediatrics at CHKD, says that early sexual maturity puts the children at risk of early sexual activity, pregnancy, and more STDs. "It's horrible," he adds. Studies have linked it to various health risks including depression. Studies have also linked a younger age at the first menstrual period to a higher risk of breast cancer after menopause.
Shari Roan, Los Angeles Times, contributed to this story.
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New research reveals more and more American girls starting puberty by age 8
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