Your Changing Body: Puberty in Girls

Puberty is the time when your body changes and becomes more like an adult.

It is normal for changes to start as early as age 8 or as late as 13. Puberty starts when your brain sends signals to certain parts of the body to start growing and changing. These signals are called hormones. Hormones are chemicals that control body functions.

During puberty, hormones cause the following changes:

• You grow taller and gain weight.

• Your hips may get wider.

• Your breasts grow.

• You grow hair under your arms and around the vulva.

• Your body odor may change.

• You may get acne or pimples.

• You get your first menstrual period (also called menstruation).

An obstetrician–gynecologist (ob-gyn) is a doctor who specializes in the health care of women. You should have your first visit with an ob-gyn between the ages of 13 and 15.

The first visit may be just a talk between you and your doctor. You can find out what to expect at future visits and get information about how to stay healthy. You can ask questions about your body, growing up, and sex. Read Your First Gynecologic Visit to learn more.

A change in your breasts may be the first sign of puberty. As your breasts start to change, the darker areas around the nipples (called the areolas) may look swollen. The breasts also grow rounder and fuller.

One breast may seem a little larger than the other. They may feel sore at times. This is all normal.

Over time, for many girls, the breasts become closer in size. For as many as 1 in 4 girls, the differences in size may not go away.

Acne is caused by overactive glands in the skin. The glands make a natural oil called sebum. During puberty, these glands make extra sebum that can clog the pores in your skin.

Wash your face often with water and mild cleanser to help get rid of the extra sebum. This will help reduce pimples and acne. Avoid products that dry or irritate your skin. Do not scrub or pick at your skin. If you have concerns about acne or pimples, some medications can help. Talk with your doctor about your concerns.

Beginning in puberty, every month your body will prepare for a possible pregnancy. Hormones signal the ovaries to release an egg each month. The egg moves into one of the fallopian tubes. At the same time, the lining of the uterus begins to grow and thicken. If the egg is not fertilized by a man’s sperm, pregnancy does not occur. The lining breaks down and flows out of the body through the vagina. This is called menstruation, the menstrual period, or just your "period."

There is no good way to tell when you will begin to have periods. Menstruation usually starts about 2 to 3 years after the breasts start developing. Most girls in the United States start between the ages of 12 and 14, but some start earlier or later.

Periods usually last between 2 and 7 days. They normally come every 21 to 45 days. They are often not regular at first. You may miss a period. You may have two periods in 1 month. This is normal. It can take about 1 to 2 years after your first period for your body to get on a regular cycle.

[Heavy and Abnormal Periods]

Keep in mind that if you have had sexual intercourse, a missed period can be a sign that you are pregnant.

It is best to be prepared for your period, even if you have not started yet. Have pads, tampons, or a menstrual cup ready at home and carry them with you to school. You can also consider buying period underwear to have at home and wear after you get your period. Read Your First Period to learn more.

Pads attach to the inside of your underwear. Period underwear has built-in protection. Pads and period underwear absorb the blood as it leaves the vagina. Tampons and menstrual cups are inserted into the vagina. They catch the blood before it leaves the body. Tampons absorb the blood, and menstrual cups collect the blood in a small cup.

You should change your pad or tampon at least every 4 to 8 hours. On the first days of your period, you may need to change it more often because your flow may be heavier.

If you use a menstrual cup, you should empty, wash, and reinsert it at least 2 times per day.

Period underwear can be worn for a full day. They may need to be changed more often depending on your flow and the type of underwear.

Using tampons has been linked to an illness called toxic shock syndrome. Toxic shock syndrome is rare, but you should still take steps to prevent it.

Read all of the instructions that come with tampons. Use tampons with the lowest absorbency needed to absorb your flow, and do not use tampons when you do not have your period.

Some girls have cramps (tightness and pain) in the lower abdomen and back at the start of their periods. Some girls get headaches or feel dizzy. Some get diarrhea.

If these problems do not go away or if they bother you, talk with your doctor. To help ease cramps, you can try the following:

• Take ibuprofen or naproxen sodium (if you do not have an allergy to aspirin or severe asthma).

• Exercise.

• Place a heating pad on your abdomen or lower back.

Read Painful Periods to learn more.

If you have any concerns about your period, you can talk with a doctor to get help. Be sure to talk with your doctor or your parents about your period if

• you are 15 or old and have not had a period.

• it has been 3 years since your breasts developed and you have never had a period.

• you are 14 or older, have never had a period, and you have an eating disorder, exercise a lot, or have hirsutism (excessive body hair growth).

• your periods were regular each month and then they stopped being regular.

• your period comes more often than every 21 days or less often than every 45 days.

• your periods come more than 90 days apart (even if that happens only once).

• your periods last more than 7 days.

• your periods are so heavy that you have to change pads or tampons often (more than once every 1 to 2 hours).

• you have bad cramps that keep you from doing your regular activities and pain relievers don't help.

Read Heavy and Abnormal Periods to learn more.

Egg: The female reproductive cell made in and released from the ovaries. Also called the ovum.

Fallopian Tubes: Tubes through which an egg travels from the ovary to the uterus.

Hormones: Substances made in the body that control the function of cells or organs.

Menstruation: The monthly shedding of blood and tissue from the uterus that happens when a woman is not pregnant.

Obstetrician–Gynecologist (Ob-Gyn): A doctor with special training and education in women's health.

Ovaries: The organs in women that contain the eggs necessary to get pregnant and make important hormones, such as estrogen, progesterone, and testosterone.

Puberty: The stage of life when the reproductive organs start to function and other sex features develop. For women, this is the time when menstrual periods start and the breasts develop.

Sexual Intercourse: The act of the penis of the male entering the vagina of the female. Also called "having sex" or "making love."

Sperm: A cell made in the male testes testicles that can fertilize a female egg.

Toxic Shock Syndrome: A severe illness caused by a bacterial infection. It can be caused by leaving a tampon in the vagina too long.

Uterus: A muscular organ in the female pelvis. During pregnancy, this organ holds and nourishes the fetus.

Vagina: A tube-like structure surrounded by muscles. The vagina leads from the uterus to the outside of the body.

Vulva: The external female genital area.