Early bloomers

OBESITY may also trigger puberty at younger ages. "Fat cells make estrogen," says Cohen. "As children become more overweight, they are making more estrogen, and we are seeing earlier breast-tissue development."

How common are early bloomers? A study of more than 17,000 girls found that 15 per cent of Whites and 48 per cent of African- Americans between ages eight and nine had entered puberty; some even had signs of budding breasts and pubic hair at age seven. "Girls are starting puberty in second or third grade," says Marcia E. Herman-Giddens, Dr. P.H., adjunct associate professor of maternal and child health at the University of North Carolina at Chapel Hill, who conducted the study. "I do not think that is what nature intended."

Experts debate the cause of these changes; in addition to obesity, better nutrition and fewer infectious diseases surely play a role in girls. Another problem that may be responsible for the shift - endocrine disrupters, a variety of substances found in pesticides, plastics and even some foods that block or mimic the action of hormones. Although it is nearly impossible to prove a direct link between endocrine disrupters and early puberty, some experts are scrutinising several substances. Last year, the Consumer Product Safety Commission asked toy manufacturers to remove phthalates, a class of chemicals that makes polyvinyl chloride (PVC) products soft and flexible, from their products. And the Environmental Protection Agency reported in July that one type of phthlate, diethylhexyl phthalate (DEHP), may affect the development of the male reproductive tract.

Regardless of the cause, experts want parents to know that it is now the norm for children to start puberty earlier - a study in the journal Pediatrics even suggested revising the standard guidelines used by physicians - so that they can talk to their children about their changing bodies.

It is also important for parents to be prepared for the psychological and social adjustments their children will face. "Twenty or 30 years ago, the age of menarche (when a girl begins menstruating) was 13 to 14; now it is 12 or 121/2 says William L. Clarke, M.D., paediatric endocrinologist and professor of paediatrics at the University of Virginia Health Science Centre, in Charlottesville. "For a younger child, these processes are difficult to understand no matter how well they are explained." And studies show that early bloomers are more likely to engage in risky behaviours, including underage drinking and early sex.

Those who enter puberty early may face long-lasting health effects. "If the age of menarche is less than 12, you have a 20 per cent higher risk of developing breast cancer than someone who started at age 14," says Paul Tartter, M.D., associate professor of surgery at Mount Sinai School of Medicine, in New York.

Though exercise is certainly important to promote good health no matter what your age, for preteens, it can delay early puberty. Some studies suggest that girls who are athletes start puberty later than those who are sedentary. Exercise also protects against cancer and can boost self-esteem.

LHJ

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