When Should Puberty Start in Girls and Boys?

When do girls and boys start puberty, and what age is too young or too late? What is the sequence of bodily changes that take place?

Puberty normally occurs in a series of five stages (Tanner stages) that typically begins between the ages of 8 and 13 for girls and 9 and 14 for boys. Puberty is considered early (precocious) if it occurs before the age of 8 years in girls and 9 years in boys and is considered late or delayed if it has not begun prior to the age of 13 years for girls and 14 years of age for boys.

Recent studies have shown that puberty is occurring at an increasingly earlier age in children.

The first sign of puberty in girls, which occurs at an average age of 10 1/2 years, is breast development (thelarche). This begins with breast budding or the formation of small lumps or nodules under one or both nipples. These lumps may be tender and they may be different sizes at first. This is usually also the beginning of their growth spurt.

Next, in about six months, pubic hair develops (adrenarche), although, in some children, pubic hair is the first sign of puberty, and then axillary hair begins to grow. Breast size continues to increase and there will be a progressive increase in the development of pubic hair and the external genitalia.

A girl's first period (menarche) usually occurs about two years after puberty begins (at an average age of 12 1/2 to 13 years). This often coincides with their peak in height velocity.

Development continues and the whole process is completed in 3-4 years, eventually reaching adult breast and areolar size and an adult pattern of pubic hair. A child will have also reached her final adult height about two years after menarche.

Puberty generally begins later in boys, at an average age of 11 1/2 to 12 years, with a "normal" range being considered from 9 to 14.

The first sign of puberty in boys is an increase in the size of the testicles. This is followed a few months later by the growth of pubic hair. Puberty continues with an increase in the size of the testicles and penis and continued growth of pubic and axillary hair.

Boys undergo their peak growth spurt about 2-3 years later than girls. Also, this usually begins with an enlargement of the hands and feet and is later followed by growth in the arms, legs, trunk, and chest. Other changes include a deepening of the voice, an increase in muscle mass, the ability to get erections and ejaculate (especially spontaneous nocturnal emissions or 'wet dreams'), and in some boys, breast development (gynecomastia).

Development continues and the whole process is completed in 3-4 years, eventually reaching adult testicle and penis size and an adult pattern of pubic hair. This is followed by the development of chest and facial hair. During this three- to four-year period, most boys will grow 13 to 14 inches and gain 40 pounds.

Puberty is also associated with adolescents beginning to have axillary perspiration and body odor, and acne.

Early or precocious puberty is considered puberty before the age of 8 in girls and before the age of 9 in boys. Causes can be genetic, some medical conditions, or psychological factors. Since the consequences of precocious puberty can include depression, an increased risk of substance abuse, and lowered self-esteem, it's important to talk with your pediatrician if your daughter shows any signs that suggest early development. While the consequences of early puberty in boys are not as severe, on average, it is still very important to talk with your pediatrician.

Puberty is considered late or delayed if it has not begun by the age of 13 years for girls and 14 years for boys. Delayed puberty can be as upsetting to kids as early puberty, as they watch their friends mature while they lag behind. Often the cause is genetic, and late puberty runs in families. There can also be medical reasons for delayed puberty, and it is important to have your pediatrician thoroughly evaluate your teen if she is falling behind what you would expect her developmental milestones to have been at her age.

Along with age and body development, the teen years can be a wild roller coaster ride.

Take a moment to learn about some of the more common concerns teens face, such as treatments for teenage acne. Learn about cutting and self-harm behaviors and eating disorders, and what to do if you suspect your teen is struggling with these behaviors.​

Though none of us wish to think our teens would ever become involved in these things, make sure to learn about other teen issues and challenges, such as drug use and the choking game. Thankfully, most teens make it through these tumultuous years without major mishaps. Studies tell us that parents that communicate well with their teens may have an easier time.