American girls are hitting puberty earlier than ever — a change that puts them at higher risk for behavioral problems as adolescents and breast cancer as adults, a new study shows.
About 15% of 1,239 girls studied showed the beginnings of breast development at age 7, according to an article in today's Pediatrics. One in 10 white girls, twice as many as in a 1997 study, showed breast growth by that age, as did 23% of black girls and 15% of Hispanic girls.
The median age of breast development fell from 10.9 years in 1991 to 9.9 in 2006, according to a Danish study published in Pediatrics last year.
The new study doesn't explain why girls are developing earlier, but it did find heavier girls with a higher body-mass index were more likely than others to begin puberty early, says pediatrician Frank Biro, director of adolescent medicine at Cincinnati Children's Hospital Medical Center.
A growing number of researchers also are concerned about hormone-disrupting chemicals in the environment.
Source: USA Today