Over the last few centuries the onset age of puberty has dropped significantly.
In the early 1900’s the average age that a girl started puberty was 14.5 and now in 2010, the age of puberty beginning is 10.5 and is continuing to decrease by every four to five months with each decade.
The beginning for puberty for girls doesn’t mean they’re getting their periods or wearing bras at this moment in time, they will most likely get their period about two years after puberty begins after breast budding, the start of seeing pubic hair, and a growth spurt). It’s also noted that girls may be staying in puberty longer, not getting their period until 11, 12, or 13 years old and continuing to be in a puberty phase before that for an extended time.
In the medical journal Pediatrics, a study of 1,200 girls studied over the course of seven years noted that black girls started puberty at the average age of 8.8 years old, Hispanic girls at the average age of 9.3 years old, and White and Asian girls averaged the same at 9.7 years old. These are averages and of course the numbers vary but the age range of this study, published in 2010 is telling for puberty starting earlier and earlier.
Why is Puberty Age Dropping?
The medical community still doesn’t have a definitive WHY as to why puberty is starting earlier, but there are three theories involving the girls body, the girls home life, and the girls environment.
The first sign of puberty is breast budding. And this tends to happen earlier in girls with a higher body mass index, the determining factor for obesity. As there are more obese children than ever before, this is a theory for why puberty is starting to happen much earlier on average.
The CDC stated that children with obesity in the US has tripled since the 1970s and one in five children is obese. Body fat creates a surplus of estrogen in the body, and that means that girls can start their puberty at a younger age.
Girls Home Life
There have been studies on stress where it can factor into headaches and heart disease, so researchers believe stress may also have to do with the onset of early puberty. If there are high levels of stress in the home, parents going through a divorce, the death of a loved one, poverty, or sexual abuse, these stressors can actually change the neural endocrine system functions and can cause a girl to go through puberty early.
There are also all kinds of chemicals that we now live with on a daily basis that increase a girl’s exposure to developing puberty early. These chemicals called Endocrine disrupting chemicals or EDCs are found in pesticides and plastics and can mimic the estrogen hormone in the body, which ultimately starts puberty. These are unfortunately all around us, you might recognize seeing a plastic water bottle that says it is BPA free, this BPA is a type of EDC that has been used since the 1960s.
Unfortunately it is hard to do anything about the chemicals that are inherent in our environment, but the biggest thing we can do to help girls is to start working towards healthier meals and physical activity to try to tackle obesity.