The physical changes of puberty are beginning to show up earlier than ever before in young girls, a recent study has found. The changes may begin as early as age seven, a fact that means that parents and educators may need to re-think how and when to begin to discuss reproduction.

Puberty is a several-year process during which a child's body matures and becomes capable of sexual reproduction. Changes in hormone levels within the body cause the development of breasts, internal and external sexual organs, changes in the pattern of hair growth and muscle and fat distribution and other physical features. An increase in the rate of growth, known as the "growth spurt," is a hallmark of puberty.

The findings show that the number of white, non-Hispanic, girls beginning puberty while still in grade school has nearly doubled since 1997.

When puberty occurs unusually early or unusually late, it may be a sign of an underlying health problem and it may also cause health problems as well as emotional stress. Endocrine disorders, genetic diseases, malnutrition, and chronic illnesses are some causes of mis-timed puberty.

In girls, the earliest sign of puberty is breast development. When periods begin, pubertal maturation is considered to be complete. Health care providers can accurately determine what stage of puberty a girl is in by noting which of five stages of breast development she has reached.

When a girl has reached breast development, stage 2, she is considered to have begun the sequence of pubertal maturation. This stage is also related to other physical and hormonal pubertal changes that are taking place within her body.

The new study, published in the September issue of Pediatrics, assessed the pubertal development of three geographically separate populations of girls. Researchers assessed 1239 girls ages 7 and 8 years in New York City, California and Ohio.

They found that puberty does indeed begin earlier, when compared to the findings of a similar survey done in 1997. The current study found that it begins between ages seven and eight for 10.4% of non-Hispanic white girls, 23.4% of black girls, and 14.9% of Hispanic girls. By ages eight to nine years, these percentages rose to 18.3% non-Hispanic white, , 42.9% black, and 30.9% Hispanic.

The findings show that the number of white, non-Hispanic, girls beginning puberty while still in grade school has nearly doubled since the 1997 survey. That earlier survey found that at age seven to eight years, 5% of white, 15.4% black non-Hispanic girls had begun pubertal development.

The timing of the onset of puberty is known to be related to multiple factors including nutrition, body fat, genetics, and environment. Breast cancer researchers have been interested in earlier maturation because studies have shown that women who have breast cancer have reached their pubertal maturation earlier than their healthy peers, and women who begin their periods younger than their peers have a higher risk of breast cancer. Scientists have speculated that puberty may represent a time when breast tissue is vulnerable to factors such as environmental toxins that may lead to the development of cancer. Another theory suggests that women whose breast tissue develops early having a longer period of exposure to their body's own estrogen and progesterone.

Parents who have concerns about their daughters' pubertal development should consult with their physicians. Although breast development is occurring earlier in general, there are ages at which it is still considered too early and requires a careful medical evaluation.

Parents of normally developing 7-10 year olds must be aware that their daughters require age-appropriate sex education younger than they may have anticipated. They must also be aware that their daughters may not be emotionally prepared to handle the way their peers or other adults respond to their developing bodies. The onset of menstruation predictably follows normal breast development, and young girls, when they begin developing must also be prepared to understand the process and care for themselves when their periods begin.