Padded bras for kindergarten girls with growing breasts to make them more comfortable? Sixteen percent of U.S. girls experiencing breast development by the age of 7? Thirty percent by the age of 8? Clearly something is affecting the hormones of U.S. girls--a phenomenon also seen in other developed countries. Girls in poorer countries seem to be spared--until they move to developed countries.
No scientists dispute that precocious puberty is on the rise but they do not agree on the reasons. Is it bad diets and lack of exercise which cause growing obesity? Is it soft drinks themselves, even when not linked to obesity? Is it the common chemicals known as "endocrine disrupters" which exert estrogen-like effects (and also cause obesity)? Is it the many legal, unlabeled hormones used in U.S. to fatten livestock? Some researchers even believe precocious puberty could be triggered by sociological factors like having no father in the home or even stress.
The reason weigh gain affects puberty "is because when the body senses it has extra calories, enough to sustain a pregnancy, the fat tissues release a signal into the bloodstream," reports KATU 2 News. "That signal then travels to the brain, telling it that sexual development is a 'go.' Doctors see the opposite happen in girls who suffer from anorexia. When the body is starved of calories, the first thing it does is shut down sex hormones."
Leptin, a protein produced by fatty tissue and believed to regulate fat storage in the body, is also a factor. Fat children have high levels of the protein leptin, which through a complicated chain involving the hypothalamus and pituitary gland, can stimulate the release of the three main hormones in puberty: hypothalamic ￼gonadotropin-releasing hormone, luteinizing hormone and follicle-stimulating hormone which encourage puberty.
What's Wrong with Precocious Puberty?
There are many reasons why precocious puberty is undesirable. "Girls with earlier maturation are at risk for lower self-esteem and higher rates of depression. They are more likely to be influenced by older peers and more deviant peers, and initiate intercourse, substance use, and other norm-breaking behaviors at younger ages," writes Frank M. Biro, MD, in the journal Pediatrics. "The biologic impact of earlier maturation includes greater risk of several cancers, including breast, ovarian, and endometrial cancer, as well as obesity, hyperinsulinemia, and hypertension."
Precocious puberty usually means the girls won't grow as tall and may be stocky. "The early occurrence of puberty shortens the duration of pre-pubertal growth in a fashion that is not compensated for by an increase in peak amplitude," says a paper in the Oxford journal. In historical studies, "there was a negative correlation between the age of onset of precocious puberty and adult height, confirming the poor height prognosis of the most severe and early cases."