Earlier breast development is now so typical that the Lawson Wilkins Pediatric Endocrine Society urged changing the definition of "normal" development. Until 10 years ago, breast development at age 8 was considered an abnormal event that should be investigated by an endocrinologist. Then a landmark study in the April 1997 journal Pediatrics written by Marcia Herman-Giddens, adjunct professor at the School of Public Health at the University of North Carolina, Chapel Hill, found that among 17,000 girls in North Carolina, almost half of African Americans and 15% of whites had begun breast development by age 8. Two years later, the society suggested changing what it considered medically normal.Bottom Line: We change our (social and physical -- obesity and chemicals) environment and it changes us (social and physical -- younger maturity in girls), and that affect the environment. Remember: Nature Moves Last.
"The explanation for which there's the most evidence is that it's related to the trend in increasing obesity," he says. "There are other factors, such as if your mother matured early. Sometimes we simply don't know. But overall, the biggest single factor is the trend toward obesity." Fatty tissue is a source of estrogen, so chubbier girls are exposed to more estrogen.
"With environmental influences, there has been a lot of speculation, but little hard data. I'm not suggesting there's no connection, but it's very hard to say there's a proven connection. I think it's environmental mainly in the sense that overeating and lack of exercise is environmental," Kaplowitz says. "I've tried to take the view that we shouldn't be alarmed about this."
28 Jan 2008
The LA Times writes on girls maturing earlier than in the past: