Obesity may cause earlier puberty in girls, says new study

Obesity may cause earlier puberty in girls, says new study
NEW YORK: Obesity and overweight among girls could be the contributing factors for an earlier onset of puberty among them, according to a study by scientists at the University of Michigan's Mott Children's Hospital.

The researchers said the reasons for such a condition are not clear.

The study covered 354 girls and the researchers found that girls having a higher body mass index than normal at age three and whose BMI saw large increases between three years and first grade were associated with earlier puberty -- say around the age nine.

Dr Joyce Lee, who led the researchers, said the finding that increased body fatness is associated with the earlier onset of puberty provides additional evidence that growing rates of obesity among children may be contributing to the trend of early maturation in girls. "Previous studies had found that girls who have earlier puberty tend to have higher body mass index, but it was unclear whether puberty led to the weight gain or weight gain led to the earlier onset of puberty. Our study offers evidence that it is the latter," she said.

Studies in the past have indicated that girls in the U.S. have been reaching puberty at an earlier age than they were 30 years ago. Since rates of childhood obesity have also significantly increased during the same period, researchers tended to think that childhood obesity could be contributing to a trend of earlier puberty in girls.

The study subjects were selected from diverse socioeconomic backgrounds in 10 regions of the country using data from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development study. While recording BMI and weight status from ages three to 12, the researchers also studied multiple outcomes of puberty in girls, including breast development as well as their ages at the onset of menstrual periods. The girls were classified as at risk for overweight if their BMI was between the 85th and 95th percentiles, and defined as overweight if their BMI was greater than the 95th percentile for weight based on age and height.

The researchers found that by fourth grade, 30 per cent of the girls were either at risk for overweight or already overweight. Additionally, 168 of the participants were considered "in puberty" by fourth grade. Nearly two dozen of the girls reported having their first menstrual period by sixth grade.

The researchers also concluded that higher BMI scores at all ages had a strong association with an earlier onset of puberty in girls. Earlier onset of puberty was also associated with higher BMI change between age 3 and first grade -- a period well before the onset of puberty.

Details of the study have been published in Pediatrics, the journal of the American Academy of Pediatrics.

The study says earlier onset of puberty is associated with a number of adverse outcomes, including psychiatric disorders and deficits in psychosocial functioning, earlier initiation of alcohol use, sexual intercourse and teenage pregnancy and increased rates of adult obesity and reproductive cancers.