Introduction:
When childhood is ending, it often feels like it has all gone by too fast. It’s bittersweet watching our children’s bodies change into those of young men and women. How much more poignant when puberty arrives earlier than expected!

What is it?
The age of onset of puberty varies widely. In girls, the breast bud is usually the first sign, and is seen on average at 10-11 years. Pubic hair usually begins to appear 6-12 months later. Next comes the pubertal growth spurt. Menstruation begins, on average, 2 to 2.5 years after the onset of puberty. The mean age for a girl's first period is about 12 years. Wide variations are seen in the sequence and timing of these events, but the peak growth spurt always precedes the first period.

In boys, testicular enlargement is the first sign of puberty and is seen on average at 11-12 years. Further testicular enlargement, penile enlargement, and pubic hair development follow. The peak growth spurt for boys typically occurs later than for girls.

Precocious puberty is often defined as the onset of true puberty before 8 years of age in girls or 9 years of age in boys. (Isolated breast development that doesn’t progress to the rest of puberty is called premature thelarche, and is a different, benign condition).

Who gets it?
Precocious puberty is 10 times more common in girls than in boys.

Most precocious puberty is simply early maturation. When puberty occurs before 6 years of age, it is important to look for other causes such as ovarian cysts, thyroid problems, McCune-Albright syndrome, or external sources of estrogen. In girls over age 6, these other causes are quite rare, but should at least be considered by your pediatrician.

What are the symptoms?
In girls, the signs to watch for are the development of the breasts, the growth of pubic hair or underarm hair, a change in the appearance of the external genitals, and the beginning of menstrual periods.

In boys, watch for enlargement of the testicles or penis, the appearance of pubic hair or underarm hair, acne, and the deepening of the voice.

Increased height and weight may be seen in boys or girls.

Early maturation may be divided into three main types: rapidly progressive, slowly progressive, and unsustained. Most girls who begin puberty early (especially those who begin before age 6) have the rapidly progressive variety. They go through each of the stages (including closure of the growth plates of the bones) at a very rapid pace, and thus lose much of their adult height potential. About 1/3 of these girls will end up shorter than the 5th percentile of adult height. Many girls, however (particularly those beginning puberty after their 7th birthdays), will start puberty early, but still go through each of the stages at a more typical pace. While their "adolescent" growth spurts are over early, they will continue to grow until their bones reach final maturity at about age 16.

A few have unsustained early puberty: the changes of puberty begin and then stop.

Is it contagious?
No

How long does it last?
Sexual development may begin at any age. Pregnancy has been reported as early as 5 1/2 years old.

How is it diagnosed?
Early puberty is suspected on the basis of the physical examination. Laboratory tests are important to determine which puberty hormones are present, and where they are coming from.

How is it treated?
Medicines are available to slow or stop early puberty. Sometimes surgery is needed to remove ovarian cysts, or other ongoing sources of puberty hormones.

Children with early puberty tend to have the mental development of their chronologic age clashing with the emotional surges of adolescence. These children deserve extra understanding and support.

How can it be prevented?
Often early puberty cannot be prevented. We do know that exposure to puberty hormones such as estrogen can trigger some types of early puberty. Reducing children’s exposure to estrogen or other sex hormones is wise.