Girls in the U.S. may be continuing to hit puberty at earlier ages, according to new research.
The findings suggest earlier development than what was reported in a 1997 study and show a worrying pattern, say the study’s authors, led by Dr. Frank Biro of Cincinnati Children’s Hospital Medical Center.
Girls who hit puberty earlier are more likely to engage in risky behavior, Biro’s team notes, and might be at a higher risk for breast cancer, than their peers who develop later.
“This could represent a real trend,” Dr. Joyce Lee, a pediatric endocrinologist at the University of Michigan who was not involved with the new research, told Reuters Health.
Doctors are unsure of what could be causing girls to develop at a younger age, but rising obesity rates may be to blame, they say.
In a study published today in Pediatrics, Biro’s team examined about 1,200 girls aged 7 and 8 in Cincinnati, New York and San Francisco. Researchers, as well as the girls’ doctors and nurses, used a standard measure of breast development to determine which girls had started puberty.
Compared to the 1997 findings, girls in the current study — especially white girls — were more developed at a younger age. As previous research has shown, there were also large differences in development based on race. REUTERS
At age 7, approximately 10 percent of white girls and 23 percent of black girls had started developing breasts, compared to 5 percent of white girls and 15 percent of black girls in 1997.
At age 8, 18 percent of white girls and 43 percent of black girls had entered puberty — an increase from 11 percent of white girls from 1997, but the same as black girls in that year.