Puberty and Sexual Development
 

Puberty is an important part of normal growth and development. The timing and rate of progression vary among healthy children.
 

Health care providers may use Tanner stages to describe physical progression through puberty. Tanner staging ranges from Stage 1 (prepubertal) through Stage 5 (adult physical development).
 

Pubertal development involves two related but partly independent hormonal processes:
 

• Gonadarche: Activation of the reproductive hormonal system, resulting in breast development in girls and testicular and genital development in boys.

• Adrenarche: Increasing production of adrenal androgens, which contributes to pubic and underarm hair, body odor, oily skin, and acne.

Because these processes are partly independent, pubic hair alone does not necessarily mean that true central puberty has begun.
 

Puberty in Girls
 

The first sign of true central puberty in most girls is breast budding (thelarche), which normally begins between approximately 8 and 13 years of age.
 

Other changes during puberty include:
 

• Enlargement and maturation of the breasts

• Growth of pubic and underarm hair

• Increased body odor

• Acne or oily skin

• Rapid increase in height

• Development of the hips and other changes in body composition

• Menstruation

The first menstrual period (menarche) usually occurs approximately 2–3 years after breast development begins.
 

Breast Size
 

There is a very wide range of normal breast size.

Small breasts do not by themselves indicate abnormal development. What matters clinically is whether breast development began and progressed appropriately.

For example, an adolescent with small breasts who began breast development at a normal age, progressed normally through puberty, and has otherwise normal pubertal development generally does not have a developmental abnormality simply because her breasts remain small.

Some breast asymmetry is also extremely common during puberty.
 

Evaluation may be appropriate when:
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• There is no breast development by age 13

• Breast development begins but then stops progressing

• Puberty otherwise appears significantly delayed

• There is substantial or concerning breast/chest asymmetry or a mass

• Menstruation does not begin within the expected timeframe

Puberty in Boys
 

The first sign of true central puberty in most boys is testicular enlargement, generally beginning between approximately 9 and 14 years of age.
 

This is followed by other changes including:
 

• Penile growth

• Growth of pubic and underarm hair

• Increased body odor

• Acne or oily skin

• Growth of facial and body hair

• Deepening of the voice

• Increased muscle development

• Rapid increase in height

Micropenis
 

A micropenis is a penis that is structurally normal but has a stretched penile length more than 2.5 standard deviations below the mean for age.

Micropenis is generally identified at birth or during infancy and is defined by an abnormally short stretched penile length for age. True congenital micropenis is present from early life rather than suddenly developing later in childhood. However, inadequate penile growth may also become apparent during puberty in boys with hormonal disorders that impair normal pubertal development.

It is important to distinguish true micropenis from an inconspicuous or buried penis. Surrounding tissue—particularly suprapubic tissue—can make the penis appear unusually small even when its actual stretched length is normal.

Pubic Hair and Adrenarche
 

Pubic and underarm hair are important signs of maturation, but they are primarily influenced by androgens produced by the adrenal glands.
 

Adrenarche may produce:
 

• Pubic hair

• Underarm hair

• Adult-type body odor

• Oily skin

• Mild acne

Adrenarche often occurs around the same general time as puberty but is hormonally distinct from the process responsible for breast development in girls and testicular enlargement in boys. For example, a girl may develop pubic hair and body odor while having no breast development. This indicates adrenal androgen activity but does not necessarily mean that central puberty has begun.

Premature Adrenarche
 

Premature adrenarche refers to the early appearance of signs of adrenal androgen activity, generally before age 8 in girls or before age 9 in boys, without other evidence of true central puberty.
 

Signs may include:
 

• Pubic hair

• Underarm hair

• Body odor

• Oily skin

• Mild acne

Premature adrenarche is often a benign variation of development, particularly when the child otherwise appears healthy and development progresses slowly. However, evaluation may be appropriate to distinguish benign premature adrenarche from other causes of excessive androgen exposure or production.

Concerning findings can include:
 

• Rapid progression of pubic hair or other changes

• Significant growth acceleration

• Markedly advanced bone age

• Severe acne

• Deepening of the voice

• Clitoral enlargement in girls

• Significant penile enlargement in boys

• Other signs of virilization

Less common causes of early androgen effects include congenital adrenal hyperplasia, androgen-producing adrenal or gonadal disorders, and exposure to testosterone or other androgen-containing medications or products.

Depending on the presentation, evaluation may include growth assessment, physical examination, bone age, and selected hormone testing.

Premature Thelarche
 

Premature thelarche is isolated breast development in a young girl without other signs of true progressive puberty.

It occurs most commonly in infants and young girls and is often a benign and temporary variation.
 

A child with premature thelarche generally has:
 

• Breast tissue development

• No significant pubic or underarm hair attributable to puberty

• No menstrual bleeding

• No significant pubertal growth spurt

• No other progressive signs of estrogen exposure

Premature thelarche may remain stable or resolve on its own. However, continued monitoring is important because occasionally apparent premature thelarche can represent the beginning of central precocious puberty.

More concerning findings include:
 

• Rapidly progressing breast development

• Rapid increase in height

• Advanced bone age

• Vaginal bleeding

• Development of multiple other pubertal signs

These findings may warrant further evaluation.

Precocious Puberty
 

True precocious puberty generally refers to development of secondary sexual characteristics:
 

• Before age 8 in girls

• Before age 9 in boys

Importantly, an isolated early pubertal-appearing feature does not necessarily mean that a child has precocious puberty.

For example:
 

• Pubic hair/body odor alone may represent premature adrenarche.

• Isolated breast development may represent premature thelarche.

True central precocious puberty typically produces a progressive pattern of pubertal development, often accompanied by accelerated growth and advancement of bone maturation.

Depending on the child's age and findings, evaluation may include:

• Detailed history and physical examination

• Review of growth velocity

• Tanner staging

• Bone-age X-ray

• LH and FSH

• Estradiol in girls or testosterone in boys

• Thyroid testing

• Adrenal androgen testing when indicated

• Additional endocrine testing

• Brain imaging in selected children

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Delayed Puberty
 

Evaluation for delayed puberty is generally appropriate when:
 

• Girls: No breast development by approximately age 13

• Boys: No testicular enlargement by approximately age 14

Evaluation may also be appropriate when puberty begins but fails to progress normally.

Possible causes include:
 

• Constitutional delay of growth and puberty

• Low body weight or inadequate nutrition

• Excessive exercise

• Chronic medical illness

• Disorders affecting the ovaries or testes

• Pituitary or hypothalamic disorders

• Genetic conditions

• Other hormonal disorders

Evaluation may include growth history, Tanner staging, family history of pubertal timing, physical examination, bone age, and selected laboratory testing such as LH, FSH, testosterone or estradiol, and thyroid studies.