According to a new study published in the journal Pediatrics, 1 in 10 girls in second and third grade, of Caucasian descent, showed stage 2 breast development (small mounds of tissue under the nipple area), which is considered the first sign of sexual maturation. This is an increase of two hundred percent since the 1980s. For African American girls, the increase is even more alarming, with nearly one in four 7 and 8 year-olds showing the early breast signs.
The causes are unclear, but suspects include:
If the causes of premature puberty are murky, the expected effects on the next generation of women are even murkier. But there are a few things we can anticipate.
The average woman today stops growing around age 18 when she is 64 inches tall. The next generation of women are likely to be significantly shorter, since estrogen makes the growth plates in the long bones close. Usually, women grow one more inch after their periods start. So those girls who start puberty at age 7, will start their periods an average of 4 years later, at an average height of 56 inches, and may stop growing well before reaching five feet.
While not a strict rule, women who start their periods later go tend to also through menopause later, and this predicts longevity (unless a woman’s periods come late because she’s unhealthy because she’s anorexic, undernourished, or exercises excessively). The converse is also true, those who start their periods earlier tend to through menopause earlier and are likely to have a shorter life expectancy. The difference is relatively small and more obvious on a population level than in any given family, but real. Women who go through menopause at 55 live an average of two years longer than women who go through menopause at age 40.
Study from the journal Pediatrics: Pubertal Assessment Method and Baseline Characteristics in a Mixed Longitudinal Study of Girls Frank M. Biro, Maida P. Galvez, Louise C. Greenspan, Paul A. Succop, Nita Vangeepuram, Susan M. Pinney, Susan Teitelbaum, Gayle C. Windham, Lawrence H. Kushi and Mary S. Published online Aug 9, 2010
Growth charts for girls aged 2-18 http://www.kidsgrowth.com/stages/viewgrowthcharts.cfm?id=GH318
Late menopause linked to long life http://www.medicineonline.com/news/12/919/Later-Menopause-Linked-to-Longer-Life.html