Children's Health: Overweight Girls at Risk of Early Puberty
Add one more to the growing list of concerns about the rise in childhood obesity: Researchers now find that overweight girls begin puberty about a year ahead of schedule, at age 9. Previous studies have shown that girls who go through early puberty are more likely to experiment with sex and alcohol at younger ages–and are at greater risk than their peers of teen pregnancy and juvenile delinquency. Research also indicates that American girls are entering puberty at younger ages today than 30 years ago, which could be related to the increase in body weight.
The eight-year study, published Monday in the journal Pediatrics, followed 354 girls from age 3 to age 11 to see how body weight in relation to height–known as body mass index–affected breast development and age of menstruation. By age 9, about 80 percent of the girls determined to be obese had begun to develop breasts, an early sign of puberty, compared to 58 percent of those who were overweight and 40 percent of those who were within the normal weight range. Those whose body mass index increased most rapidly over time were far more likely to have gotten a period by age 11. The study also found that African-American girls and girls whose mothers menstruated before age 12, even if they were normal weight, had a greater likelihood of going through puberty before their peers.
The results are important, says study leader Joyce Lee, assistant professor of pediatric endocrinology at the University of Michigan School of Medicine in Ann Arbor, because it shows that excess weight leads to earlier puberty rather than the other way around. The finding is particularly troubling given that the number of overweight children in the United States has doubled in the past two decades. And early menstruation has been shown to be a risk factor for breast cancer. What's clear from the study, says Lee, is that parents should be stepping in earlier to reverse poor nutrition and exercise habits.