Understanding Puberty

Stages of Puberty

Sure, most of us know the telltale signs of puberty — hair growth in new places, menstruation, body odor, lower voice in boys, breast growth in girls, etc. But we may not fully comprehend the science behind all of these changes. Here's a quick look at how it works.

Usually after a girl's 8th birthday or after a boy turns 9 or 10, puberty begins when an area of the brain called the hypothalamus starts to release gonadotropin-releasing hormone (GnRH). When GnRH travels to the pituitary gland (a small gland under the brain that produces hormones that control other glands throughout the body), it releases two more puberty hormones — luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

What happens next depends on gender:

• Boys: Hormones travel through the bloodstream to the testes (testicles) and give the signal to begin production of sperm and the hormone testosterone.
• Girls: Hormones go to the ovaries (the two oval-shaped organs that lie to the right and left of the uterus) and trigger the maturation and release of eggs and the production of the hormone estrogen, which matures a female's body and prepares her for pregnancy.

At about the same time, the adrenal glands of both boys and girls begin to produce a group of hormones called adrenal androgens. These hormones stimulate the growth of pubic and underarm hair in both sexes.

For a Boy

The physical changes of puberty for a boy usually start with enlargement of the testicles and sprouting of pubic hair, followed by a growth spurt between ages 10 and 16 — on average 1 to 2 years later than when girls start. His arms, legs, hands, and feet also grow faster than the rest of his body. His body shape will begin to change as his shoulders broaden and he gains weight and muscle.

A boy may become concerned if he notices tenderness or swelling under his nipples. This temporary development of breast tissue is called gynecomastia and it happens to about 50% of boys during puberty. But it usually disappears within 6 months or so.

And that first crack in the voice is a sign that his voice is changing and will become deeper.

Dark, coarse, curly hair will also sprout just above his penis and on his scrotum, and later under his arms and in the beard area. His penis and testes will get larger, and erections, which a boy begins experiencing as an infant, will become more frequent. Ejaculation — the release of sperm-containing semen — will also occur.

Many boys become concerned about their penis size. A boy may need reassurance, particularly if he tends to be a later developer and he compares himself with boys who are further along in puberty. If a boy is circumcised, he may also have questions about the skin that covers the tip of an uncircumcised penis.

For a Girl

Puberty generally starts earlier for girls, some time between 8 and 13 years of age. For most girls, the first evidence of puberty is breast development, but it can be the growth of pubic hair. As her breasts start to grow, a girl will initially have small, firm, tender lumps (called buds) under one or both nipples; the breast tissue will get larger and become less firm in texture over the next year or two. Dark, coarse, curly hair will appear on her labia (the folds of skin surrounding the vagina), and later, similar hair will begin growing under her arms.

The first signs of puberty are followed 1 or 2 years later by a noticeable growth spurt. Her body will begin to build up fat, particularly in the breasts and around her hips and thighs, as she takes on the contours of a woman. Her arms, legs, hands, and feet will also get bigger.

The culminating event will be the arrival of menarche, her first period (menstruation). Depending on the age at which they begin their pubertal development, girls may get their first period between the ages of 9 and 16.

Common Puberty Concerns

The physical changes kids experience as they move toward adulthood often are accompanied by emotional consequences.

Some girls are excited about their budding breasts and new training bras; others may worry that all eyes are focused on their breasts. Some boys love the sight of themselves all lathered up with shaving cream; others may be uncomfortable with the attention they get for a few new shoots of hair.

Pimples are common for most teens. Acne is caused by glands in the skin that produce a natural oil called sebum. Puberty hormones make the glands produce extra sebum, which can clog the pores. Washing gently with water and mild soap can get rid of excess sebum and help reduce breakouts.

Over-the-counter and prescription medications are available for more severe cases of acne. Your family doctor can recommend a dermatologist (a doctor specializing in skin) if basic skin care and OTC medications don't keep acne under control.

Kids who once associated bath time with play need to learn to wash regularly and to apply deodorant or antiperspirant. A teen who's learning to use shave will need instructions on how to keep it clean, to throw a disposable one away before it becomes dull and ineffective, and to not share it with others.

Boys, capable of having erections since infancy, can now experience ejaculation. The first ejaculation usually occurs between the ages of 11 and 15, either spontaneously in connection with sexual fantasies, during masturbation, or as a nocturnal emission (also called a wet dream). If he doesn't know about wet dreams before he has one, a boy may think he has urinated accidentally or that something has gone wrong with his body.

As kids mature physically and emotionally, they become increasingly curious about their sexuality and their own bodies. Although infants and younger children do touch their own genitals from time to time because they like the way it feels, masturbation is more common in older kids, from the preadolescent and teen years and beyond.

As far as the myths and beliefs about masturbation: No, it won't cause kids to grow hair on their hands, become infertile, go blind, or develop new emotional problems. A small number of kids and teens with already existing emotional problems may become preoccupied with masturbation — just as they may become overly occupied with other behaviors or thoughts. Constant or obsessive masturbation may be a sign of anxiety or other emotional problem.

But, other than that, masturbation is generally considered by doctors to be a common form of normal sexual self-exploration. Although some preteens and teens may choose to masturbate, others may not.

Because masturbation is often considered a private topic, many kids might feel too embarrassed to talk about it because they're concerned that their parents will be angry or disappointed with them. Some kids may prefer to talk to older siblings, friends, or their doctors rather than a parent. If you continue to be concerned or have questions about masturbation, consult your doctor.

Talking to Kids About Puberty

Boys and girls can see these changes happening to each other — in some cases, they can smell them. It's important to talk to your child about how bodies change — sooner, rather than later.

Be prepared to talk to a girl about the expected events of puberty, including menstruation, when you see the first signs of breast development, or earlier if she seems ready or has questions. A boy should know about normal penile development, erections, and nocturnal emissions before age 12 — sooner, if he's an early developer. And it's also important to talk to your child about what's happening to members of the opposite sex.

It's best not to have "The Talk" as one grand summit but rather as a series of talks, ideally beginning when your child is young and starting to ask questions about body parts. Each time you talk, offer more and more detail, depending upon your child's maturity level and interest in the topic.

And, if your child has a question, answer it honestly. If you feel uncomfortable, need answers to questions, or are uncertain about how to have these talks with your child, ask your doctor for advice.

Reviewed by: Steven Dowshen, MD
Date reviewed: May 2010