Researchers at the University of Michigan's Mott Children's Hospital studied 354 girls over several years and discovered that those who had more body fat at 3 years of age than their counterparts were more likely to begin developing breasts, signaling puberty, by age 9.

Dr. Joyce Lee, a pediatric endocrinologist at the University of Michigan and lead author of the report, suggested that the parallel trends toward childhood obesity and early maturation among girls over the past three decades might be more than associative, and that a cause and effect relationship might exist between the two.

The study provides evidence that weight gain leads to earlier puberty, she said.

Among the study participants, 168 were classified as "in puberty" by the age of 9, and approximately two dozen began menstruating within the next two years.

Girls were considered "at risk" of being overweight if they had a body mass index (BMI) between the 85th and 95th percentiles. Those with BMIs higher than the 95th percentile were considered overweight.

At all ages, higher BMIs were linked to earlier puberty, according to the researchers.

The findings are important, because associations have been identified between early maturation and such problems as psychiatric disorders, psychosocial behavior, early use of alcohol, early sexual activity, teen pregnancy, adult obesity and reproductive cancers, states the report.

"Beyond identifying how obesity causes early puberty, it's also important to determine whether weight control interventions at an early age have the potential to slow the progression of puberty," said Dr. Lee.