Of the 1,250 women answering a recent poll on the We're Talking Teen Health Web site, 37% of them had started their period before they were 13, and 9% had started when they were only 9 years old. In addition, in another poll, 76% of 617 people reported that they started developing hair under their arms and on their genitals before they were 14, and 28% of them had started before they were 11.
There was a time when an 8- or 9-year old girl who started to develop breasts would have been considered abnormal, but that is no longer the case. More and more pediatricians are seeing breast development in younger girls. Now it is only breast development under age 8 that prompts a referral to to an endocrinologist for evaluation. Another change is the length of time between breast development and the onset of periods. It used to take about a year, but now it is not uncommon for there to be a three year gap between breast development and the beginning of periods.
What we do not know is why puberty is starting earlier, particularly in girls. There are theories out there that the early trend in pubertal development is related to better nutrition and health care, or the chemicals in our air, food, and water, which is mighty scary. There is also a tie between obesity rates and early development, with estrogen rates higher in heavier girls (the traditional early developers). There are also some health risks, for example, earlier breast development, and therefore a longer lifetime exposure to estrogen, is a known risk factor for breast cancer, but with the age dropping, "early" might now mean age 6 or 7.
There are three stages of puberty: breast development, pubic hair growth, and finally, menstruation. The average age for menstruation in the U.S. is now 12.5 for white girls, 12.06 for black girls, and 12.09 for Latinas. Another interesting change I have noticed is that we used to say that periods can be sporadic when they start - a young girl might only have one or two during the first year, but more and more I notice that when young girls start, they are quite consistent, with 21 - 35 day cycles.
The parenting implication for this drop in the age of puberty is that we have to have "the talk" with kids who seem way too young to be worrying about reproduction. However, if your daughter is starting to have breasts in third grade, then in 4th grade it is time to start keeping a calendar of mood swings and headaches that may be cyclical, give her the heads up about what her period will look and feel like, give her a Period Pack to start carrying with her, and start talking about growing up.
Sorry, but it's true - whatever the explanation, our daughters bodies are maturing when we still want them to be little girls.