Confirming previous research, a new study reports that early onset puberty in girls is linked to overweight and obesity. This isn’t totally surprising, since obesity can alter the levels of reproductive hormones, prompting the body into premature puberty. Still, the implications are important, given that overweight and obesity in children has increased markedly in recent decades – and given the number of health problems that are linked to excess body weight across a lifetime. But while obesity is a likely culprit in the early onset of puberty, there are certainly others.

The authors of the new study followed over 1,200 girls, starting at age 6 to 8, in three metropolitan areas: the San Francisco Bay Area, Greater Cincinnati, and New York City. They monitored breast development over the next 7 years. The median age of breast development was 8.8 for African-American girls, 9.3 for Hispanic girls, 9.7 for Caucasian girls, and 9.7 for Asian girls.

But beyond ethnicity, body mass index (BMI) was an even stronger indicator of earlier onset puberty. The team found a strong correlation between higher BMI and earlier breast maturation: Overweight and obese girls developed breasts about a year earlier than normal-weight girls (age 8 vs. age 9, […]