Two researchers talk about early puberty for girls–you can listen or read the transcript.
On early puberty
Louise Greenspan: The evidence suggests that in the past, age 8 was the cut-off for normal puberty, so we thought that less than 5 percent of girls were going through puberty before the age of 8. I do want to define what we mean in the medical profession by “starting puberty.” A lot of people in the lay public think that that means getting your period. What we’re talking about is actually starting with breast development and pubic hair and what the research that we did with our colleagues found was that at age 7, 15 percent of girls had breast development, and at age 8, 27 percent had breast development. And in terms of pubic hair development, at age 7, 10 percent of girls had it and by 8, 19 percent had pubic hair development. That was significantly higher that what had been found in the past.
On how the numbers vary by race
Greenspan: At age 7, 25 percent of black girls have breast development, compared to 15 percent of Hispanic girls and only 10 percent of white girls and 2 percent of Asian girls. The same pattern can be seen for pubic hair development.
On boys’ puberty
Greenspan: The jury is still out on what’s happening with boys’ puberty. There is some evidence that boys’ puberty may be starting earlier as well, but we don’t have the definitive studies that demonstrate that yet. One of the concerns is that the hormones that are estrogen mimickers might actually delay boys’ puberty because boys’ puberty is not an estrogen-related process, it’s more of a … testosterone-related process. So the same chemical may have different effects in boys versus girls in terms of their pubertal development.