Doctor: Paul Kaplowitz, M.D., Ph.D., a pediatric endocrinologist, is chief of endocrinology at the Children's National Medical Center in Washington, D.C., and the author of Early Puberty in Girls (Ballantine).
Psychologist: Diana Zuckerman, Ph.D., a psychologist, is president of the National Research Center for Women and Families in Washington, D.C., and the author of the research paper "When Little Girls Become Women: Early Onset of Puberty in Girls."
What's considered "normal" in terms of sequence of changes and age range for puberty?
DOC Puberty is marked by changes in the body. For boys, pubic hair isn't necessarily an indication that they're starting—there are other, clearer signs, like penis or testicular enlargement, which can begin as early as age 10. For girls, changes include the formation of breast tissue; pubic and underarm hair; body odor; and, finally, menarche (the first period). Their bodies change initially by developing breast buds, at an average age of 9 for African-American girls and 10 for white girls. From a parent's point of view, the thing to be concerned about is if the breasts of girls ages 6 to 8 seem to be growing rapidly over a period of four to six months, accompanied by an increased rate of overall growth—particularly height. If they're rapidly outgrowing their clothes, in other words, early puberty might be an issue. Bear in mind that parents' own growth patterns are also a factor: If the mother had her first period at 9 or 10, there's a good chance that her daughter will be an early maturer, too.
Is puberty starting earlier in today's kids?
DOC Not substantially. Evidence suggests that the average ages of breast-bud and pubic-hair development are just a half-year to a year younger than they were 40 years ago. Even the age of the first period has decreased by only about four months over the same time. In my practice, I've been seeing more patients with some signs of puberty, but most do not have full-blown precocious puberty.
What are the main psychological impacts of early puberty?
PSYCH There was some excellent research conducted 10 to 15 years ago. A national study of 1,800 girls ages 15 to 19, published in Adolescence in 1990, found that girls who started menstruation earlier than their peers tended to begin dating and having sexual intercourse younger. Another study, of 200 adolescents, published in Child Development in 1996, determined that girls who matured early experienced more psychological stress and were more vulnerable to peer pressure. And in a 1997 study of 1,700 Oregon high school girls, published in The Journal of the American Academy of Child & Adolescent Psychiatry, those who reported that they had matured earlier than their classmates were more likely to drink and smoke, and twice as likely to have had substance-abuse and disruptive-behavior disorders. They also tended to have lower self-esteem, to miss more days of school, and to be more likely to have attempted suicide. But it's important to note that the 1997 study was based on girls reporting they matured earlier—it's not definite that they actually did.
Are there gender or lifestyle factors that contribute to premature puberty?
DOC This is largely a concern for girls; we don't see many cases of premature puberty, meaning before the age of 9, in boys. One possible explanation for this is that the connection between increased body weight and early puberty doesn't exist for boys as it does for girls—early puberty in girls is mostly caused by obesity, one of the biggest health-care issues we are facing in this country. We've known for years that body-fat percentage can influence the timing of reproduction; girls who are overweight tend to mature earlier.
I published an article five years ago in Pediatrics in which we explored the link between a girl's body-mass index (BMI)—calculated from height and weight—and puberty. We found that girls in early puberty have higher BMIs, on average, than other girls. The average 7-year-old girl has a BMI of 15 or 16. A BMI of only 10 percent higher—maybe 17—would confer an increased likelihood of early breast development or pubic hair. And I don't mean to alarm anyone, but occasionally—in about 2 percent of 6- to 8-year-old girls who show signs of early puberty—the maturation is triggered by brain malformations or tumors. These girls may look like they're experiencing early puberty, but they'll have other symptoms, like more headaches and trouble with their vision. They should see a doctor right away.
PSYCH African-American girls are more likely to experience early puberty. A 1997 study published in Pediatrics showed that in their seventh year, 27 percent of African-American girls had begun to develop breasts, pubic hair, or both, compared with 7 percent of white girls. In their eighth year, those numbers increased to 48 percent of African-American girls and 15 percent of white girls.
Next Page: How should parents approach this topic with kids?
