American researchers have discovered a possible connection between obesity in young girls and an early onset of puberty. Researchers from the University of Michigan's Mott Children's Hospital report that their study of a group of 354 girls, over several years, found that those heavier around age 3, who gained additional weight over the next three years, reached puberty earlier than expected.

The study is published in the March issue of the journal Pediatrics. There have been previous studies that suggested that girls in the US enter puberty at younger ages nowadays than they were 30 years ago, according to lead author Dr. Joyce Lee. Rates of childhood obesity have also increased significantly during the same time period, and this led researchers to explore the possibility of a connection between childhood obesity and earlier puberty 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,” says Lee, a member of the Child Health Evaluation and Research (CHEAR) Unit in the U-M Division of General Pediatrics, and assistant professor in the Department of Pediatrics and Communicable Diseases at the U-M Medical School. A higher body mass index (BMI) score in girls as young as age 3, and large increases in BMI between 3 years of age and first grade are associated with earlier puberty, defined as the presence of breast development by age 9.

"Our finding that increased body fatness is associated with the earlier onset of puberty provides additional evidence that growing rates of obesity among children in this country may be contributing to the trend of early maturation in girls," said Dr. Lee. "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," she added. "Our study offers evidence that it is the latter," Dr. Lee said. "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," the study warns.