Today it has become common for girls to enter puberty before discovering Are You There God? It’s Me, Margaret. Over the second half of the 20th century, the average age for girls to begin breast development has dropped by a year or more in the industrialized world. And the age of first menstruation, generally around 12, has advanced by a matter of months. Hispanic and black girls may be experiencing an age shift much more pronounced.
The idea of an entire generation maturing faster once had a strong cadre of doubters. In fact, after one of the first studies to warn of earlier puberty in American girls was published in 1997, skeptics complained in the journalPediatrics that “many of us in the field of pediatric endocrinology believe that it is premature to conclude that the normal age of puberty is occurring earlier.” Today, more than 15 years later, a majority of doctors appear to have come around to the idea. Have a conversation with a pediatric endocrinologist, and it isn’t long before you hear the phrase “new normal.”
“If you basically say that the onset of puberty has a bell-shaped distribution, it seems to many of us the whole curve is shifting to the left,” says Paul Kaplowitz, chief of the division of endocrinology and diabetes at Children’s National Medical Center in Washington, D.C. More girls, he says, are starting puberty before age 8, putting them at “the lower end of the new normal range.”
Researchers are now turning their attention to what could be driving the trend. Many scientists suspect that younger puberty is a consequence of an epidemic of childhood obesity, citing studies that find development closely tied to the accumulation of body fat. But there are other possibilities, including the presence of environmental chemicals that can mimic the biological properties of estrogen, and psychological and social stressors that might alter the hormonal makeup of a young body.
These possibilities could also be occurring simultaneously in ways that are not understood. A study published in September in the Journal of the American Medical Association found that children with high levels of a common environmental pollutant were more likely to be obese. “Although I’m convinced that obesity is part of the story, I’m no longer convinced it’s the whole story,” Kaplowitz says.
Scientists hope more research will help explain why the puberty trend for boys isn’t as clear as it is for girls, though a recent study in Pediatrics does suggest that boys, too, may be maturing earlier. The concern is not parental squeamishness but the potential for future health consequences. Children reaching puberty too young, some data suggest, face a higher risk of cancer, bone fractures and other problems in adulthood. Doctors also fear a body that belies true age, especially in girls, could put children at risk for sexual abuse and other problems.
“The early maturing girl has greater vulnerabilities and is more likely to be involved in risky behaviors,” says Frank Biro, director of adolescent medicine at Cincinnati Children’s Hospital Medical Center. When a 9-year-old looks 12, “her peers and adults take the cues from what she looks like. But she’s still a 9-year-old.”
by Laura Bell, Science News | Read more:
Nancy Honey/Getty Images
