NCPA - National Center for Policy Analysis

Doubters Fault Theory Finding Earlier Puberty

February 22, 2001

The widespread belief that girls are now starting puberty earlier -- some as early as age 6 or 7 -- began with a single study critics say has serious problems. From July 1992 through September 1993, U.S. pediatricians assessed 17,077 girls ages 3 to 12 who came into their offices.

That study by public health professor Marcia E. Herman-Giddens, published in Pediatrics in 1997, caused some experts to suggest changes in practice guidelines, and it has led parents and social scientists to cast about for explanations.

They have attributed the change to such things as plastics in the environment or hormones in food -- so-called endocrine disruptors -- or the influence of explicitly sexual television shows on the development of girls' brains.

But writing recently in Pediatrics, some endocrinologists say the finding of earlier puberty is based on flawed science. The girls were not randomly selected but happened to go to their pediatrician, and thus there was an over-representation of girls starting puberty early.

Thus many experts believe it is premature to conclude the normal age of puberty is occurring earlier -- especially since there are no reliable studies from previous years for comparison.

Moreover, since premature puberty -- which the endocrinologists say for breast development or pubic hair is before 8 or 9 years, respectively -- can be a sign of a serious disorder, such as a tumor, some physicians fear children will not get needed diagnostic tests or treatment.

In fact, the only date in the continuum of sexual development for which good data exist is the age of onset of menstruation. It is well documented and has remained constant for half a century, occurring at about 12 years and 8 months in white girls and a few months earlier in black girls.

Source: Gina Kolata, "Doubters Fault Theory Finding Earlier Puberty," New York Times, February 20, 2001.


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