Exactly Which Girls Are Reaching Puberty Earlier?

Cristen Conger

By now, you've probably heard about the recent study in the journal Pediatrics finding that girls are reaching puberty earlier. The story has circulated widely through the news outlets, setting off public health panic waves that young girls are growing up faster, if you will, than they used to. But something caught my eye when reading reports on this story from two different news outlets. No one is talking much about exactly which girls involved in the study pool demonstrated a marked increase in precocious puberty (aka early onset puberty).

The researchers used breast size as its baseline for pubertal assessment. Specifically, 7- and 8-year-old girls were measured for their breast size, and anyone having "stage 2 breasts" was marked as having hit puberty. No other indicators, such as the age of participants' first menstrual period, were taken into account. Aside from the questionable reliability of determining pubertal maturation based solely on breast size, the headlines referring to "girls" in general hitting puberty earlier are misleading.

As CNN points out pretty quickly, the "girls" we're talking about are white. The study participant pool consisted of white, black, Hispanic and non-Hispanic girls. But the conclusion that girls are hitting puberty earlier only has to do with the white cohort. While a greater proportion of non-white girls had reached puberty by the age of 7, according to study data, around 5 percent more white girls are hitting puberty earlier compared to 10 years ago.

As the lead author Dr. Frank Biro, M.D., told CNN: "White girls are catching up."

Both CNN and ABC News quickly jump over the race factor into the health problems associated with precocious puberty, such as higher rates of breast and uterine cancer. So even though the rates of precocious puberty among minority populations are much higher - and have been for a while - we're only discussing it as a "major public health concern" now that white girls are experiencing it more.

While this study leaves a number of loose ends dangling in terms of accurately defining when girls reach puberty, the news coverage has triggered even more questions in my mind. For instance, why does ABC News barely acknowledge the racial factor in the study conclusion? And why does CNN acknowledge quickly that the findings are more pertinent to white girls but doesn't delve into how more widespread precocious puberty has affected minority girls?

Scientists need to figure out why this health trend is happening and whether childhood obesity, industrial chemicals like bisphenol A or other environmental factors are to blame. However, we also need to collectively figure out why the media and public only seem to care about this issue now that this precocious puberty has reached the white population.

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