Childhood obesity appears to be causing girls to reach puberty at an earlier age, for reasons that are not clear. Earlier onset of puberty in girls has been 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. Researchers from the University of Michigan's Mott Children's Hospital, USA, did a study wherein they followed a group of 354 girls and found that those who were fatter at the age of 3 and who gained weight during the next three years reached puberty, as defined by breast development, by age 9. Herein, the girls were classified as at risk for being overweight if their body mass index (a measurement of weight related to age and height) was between the 85th and 95th percentiles, and defined as overweight if the measurement was greater than the 95th percentile. It was found that 168 of the girls were classified as being 'in puberty' by the age of 9 and nearly two dozen reported having their first menstrual period two years later. Higher body mass index scores at all ages had a strong association with earlier onset of puberty. Previous studies have 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. The above study offers evidence that it is the latter. Earlier studies have found that girls are reaching puberty earlier than was the case 30 years ago, a time span during which rates of childhood obesity also increased.
Pediatrics,
March 2007