Obesity epidemic fuelling premature puberty in girls

Researchers in the United States say girls who are overweight at the age of three run the risk of reaching puberty as early as nine years old and warn that the obesity crisis is now affecting children's development.

The research supports a body of evidence which suggests childhood obesity is causing the trend of earlier puberty.

It has also been found that girls who reach puberty earlier than the "normal" age of 10 and above, experience increased psychological and social problems and also start drinking alcohol and have sexual intercourse sooner.

Experts say apart from increasing the risk of certain cancers such breast cancer, early puberty causes girls significant distress.

Dr. Joyce Lee and colleagues at the University of Michigan found many girls, who had been overweight as children and toddlers, reached puberty at age nine and many had been overweight from the age of three years.

In a study which tracked 354 girls from the age of three up to 12, almost half (168) showed signs of puberty such as breast development, and the start of menstruation, by their ninth birthday.

Many of the early maturers had a high 'body mass index' (BMI) throughout their childhood.

BMI is a calculation of metric weight divided by height squared, which doctors use as a measure of obesity.

The findings of the University of Michigan study supports those of Bristol University research in 2000 which suggested one girl in six reaches puberty before the age of eight, 18 months earlier than their mothers.

Scientists suspect that early puberty is triggered by the hormone leptin, which is produced by fat tissue.

Experts say girls as young as seven, eight and nine are starting their periods and going through puberty and that is another reason for tackling the wider issue of childhood obesity, as it is evident that obesity disrupts hormones throughout people's lives from early childhood to menopause.

Current research by the Karolinska Institute in Stockholm is investigating whether animals that are overfed produce more of the male and female sexual hormones that trigger puberty.

These latest findings will add to the pressure on governments in both the UK and the U.S. to tackle the rising rates of child obesity.

The research is published in the journal Pediatrics.