Obesity Linked to Early Puberty in US Girls, Study Finds

The weight of a girl is linked to when she will begin going through puberty, according to a study led by Cincinnati Children's Hospital researchers. 

Researchers monitored the stages of puberty in more than 1,200 girls in San Francisco, New York, and Cincinnati who were aged 6 to 8 at the start of the study in 2004.  Researchers found that girls with higher body mass index, a ratio of height and weight, may start developing breasts more than a year before their thinner friends - perhaps as early as second grade.

"The impact of earlier maturation in girls has important clinical implications involving psychosocial and biologic outcomes," said Frank Biro, MD, lead investigator and a physician in the Division of Adolescent Medicine at Cincinnati Children's Hospital Medical Center. "The current study suggests clinicians may need to redefine the ages for both early and late maturation in girls."

Black girls began puberty at a median age of about 8 years, 10 months, while white girls in the study experienced puberty at a median age of about 9 years, 8 months, earlier than in previous studies.

"The girls who are obese are clearly maturing earlier," said Dr. Frank Biro, a pediatrics professor at Cincinnati Children's Hospital Medical Center. "BMI is, we found, the biggest single factor for the onset of puberty."

Obesity can't be called the cause of early puberty, researchers emphasized. But it is one of several factors - along with inactivity, and chemicals in food and water - that may be affecting the hormones that trigger sexual maturation. Early maturation also results in greater risks of obesity, hypertension and several cancers - including breast, ovarian and endometrial cancer.