Girls' Body Fat at Age 5
Linked to Earlier Puberty

NEW YORK (Reuters Health) - Girls who have more body fat at age 5 tend to be closer to puberty at age 9 than other 9-year-olds who had less body fat, researchers report. And girls showing large increases in body fat between the ages of 5 and 9 also tend to show more signs of puberty at age 9 compared with other youngsters.

The new findings suggest that weight control efforts may need to start as early as preschool, according to Dr. Kirsten Krahnstoever Davison and colleagues of Pennsylvania State University, in University Park.

Some experts believe that the rising rate of obesity among U.S. children has spurred early maturation. On average, girls are starting to show the first signs of breast development at ages 8 and 9, a year earlier than 20 years ago, according to the report in the journal Pediatrics.

Both obesity and earlier puberty can have health consequences.

Obesity puts young people at risk for diabetes and raises their odds of heart disease and other health problems down the road. For girls, early puberty increases their lifetime exposure to estrogen, which may elevate the risk for breast cancer and possibly ovarian cancer.

In the new study, Davison's team evaluated 181 girls at the age of 5, 7 and 9 years. All the girls underwent weight and body fat measurements, and at age nine had pubertal development assessed. All the girls were white and from families with a median annual income that ranged from $35,000 to $50,000.

"Girls with higher percent body fat at 5 years, and girls with higher percent body fat, higher BMI (body mass index) percentile, or larger waist circumferences at 7 years, were more likely to be classified with earlier pubertal development at 9 years," the authors write.

Body mass index is a measurement that takes into account a person's height and weight and is used to identify people who are overweight.

Girls who gained the highest percentage of body fat between the ages of 5 and 9, and those who saw the largest increase in their waist size between the ages of 7 and 9 were also more likely to show signs of puberty onset at age 9, the study indicates. Overall, 30 percent of the girls were overweight and 56 percent showed the first signs of breast development by age 9.

"This study indicates that body fat levels during middle childhood are causally implicated in earlier timing of puberty among white girls," the authors conclude.

"The practical implications of these findings emphasize the need for implementation of early prevention and treatment programs for childhood overweight, beginning as early as the preschool period," the authors conclude.

Further research will need to assess the relationship between weight, body fat and early onset puberty in girls of other ethnic groups, according to the report.

SOURCE: Pediatrics 2003;111:815-821.

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