Girls seem to be growing up faster these days, and not just because they dress to show more skin. Compared with their mothers, they actually have more skin to show -- and that added fat seems to be altering their rate of development.
Pediatric experts had noticed that girls appeared to be developing breasts (the first outward sign of puberty) at earlier ages -- and that they tended to gain weight around puberty. But no one knew which came first: earlier development or weight gain. By tracking girls' weights from early ages, researchers have found that the extra pounds come first.
Because both early puberty and weight gain can affect girls' health, the results add a new dimension to the importance of diet and exercise for girls.
In a study published in the March issue of the journal Pediatrics, a team of scientists monitored hundreds of girls from age 3 to 12 and found the heavier ones hit puberty earlier than their slimmer peers. Of the heaviest 15% of girls, 50% had started developing breasts by age 9. Because girls generally start puberty between the ages of 8 and 14, the researchers considered this "early," though normal, puberty.
In fact, the girls' weight as early as age 3 could predict a younger entrance into puberty, says lead study author Dr. Joyce Lee, a pediatric endocrinologist at the University of Michigan. "I thought, 'Wow, these girls are still toddlers,' " she says.
In addition, the faster girls gained weight between 3 years of age and first grade, the more likely they were to begin to develop breasts by fourth grade.
The shift toward earlier puberty has worried parents and pediatricians because some studies show that girls whose bodies mature younger tend to misbehave in school and suffer from anxiety or depression, Lee says. In addition, longer exposures to sex hormones are thought to put women at greater risk for breast cancer.
But it's the obesity that's more problematic. Health problems such as diabetes, high blood pressure and heart disease due to obesity are better documented, experts say. "Parents should try to prevent excessive weight gain in their children," Lee says.
*
What defines puberty?
Confusion over weight's effects on puberty has been fueled in part by the various definitions of puberty in previous studies.
