While most girls will get their first period around age 12, the range can run from age 8-16. Most of these girls are normal by biological standards, because puberty is a complex process of brain, body, and hormonal development. Still, there appears to be a trend toward precocious puberty mainly in girls and in some boys. Precocious puberty is the clinical term for those who experience abnormally or unusually early puberty.
Defining Normal Puberty
Every child is unique. When a child begins puberty depends on a variety of factors, including family history, ethnicity, and nutritional status.
Although there are several changes in the body, the changes usually occur in a specific order. For example, girls may see an increase in body fat and breast growth while boys experience testicular and pubic hair growth.
Until recently, normal puberty was thought to begin between ages 8 and 14 in girls and between 9 and 12 in boys. But, recent research has found that puberty occurs as early as age 6 in girls of certain ethnic backgrounds.
Rare Causes of Early Puberty
In rare cases, especially when pubic hair is seen in children as young as 5 years, precocious puberty can be caused by tumors of the adrenal gland, ovaries, testicles, or brain. It is also seen in those with brain abnormalities or rare genetic disorders, like McCune-Albright syndrome. While the appearance of pubic hair in such a young child warrants a visit to the pediatrician to rule out any serious causes, it may be just another variation on the norm.
Growth and Puberty
When puberty comes too early, it can affect growth. By late puberty, most children have reached 95% of their adult height. When puberty starts and ends too early, the sex hormones that help harden bones can end their growth too soon. Other problems may surface later in life. For example, the earlier a woman starts menstruating the more at risk she is for serious health conditions, such as breast cancer.
If tumors or other serious causes of precocious puberty are ruled out, and if a child's doctor believes the progress of puberty could harm their growth, hormone agonists can cancel the hormonal domino effect and delay puberty until a more optimal time.
The Mystery of Puberty
Scientists and clinicians would like to clarify what is normal for the onset of puberty, but the issue is clouded by the controversy of how puberty begins. The process is an intricate interplay of brain activity that leads to hormonal secretion. While experts can name most of the hormones involved in puberty, they do not know the triggers.
Obesity and Puberty
Studies have looked at the effect of increased body mass index (BMI) on earlier onset of puberty. One study found that the BMI in pubertal 6-9 year old white girls was markedly higher than the BMI in prepubertal girls of the same age. A smaller difference was noted for African American girls.
The relationship between obesity and early puberty is not clear-cut, however. Multiple factors are likely involved in the development of precocious puberty. Studies are under way to look at these potential contributing factors.
Although the condition occurs mostly in girls, boys can also undergo precocious puberty. If you are concerned that your child may have this condition, please talk to your child's doctor.
Family Doctor—American Academy of Family Physicians
Healthy Children—American Academy of Pediatrics
Caring for Kids—Canadian Paediatric Society
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Last reviewed February 2017 by Michael Woods, MD, FAAP Last Updated: 2/3/2015