During puberty, your body changes—inside and out. The changes do not come all at once, and they do not happen at the same time for everyone. It is normal for changes to start as early as age 8 years, or not until age 14 years. Even if nothing looks or feels different yet, the changes may have already begun inside your body.

This page will explain:

Changes In Girls During Puberty

As you reach puberty, a part of your brain tells your sex glands—your ovaries—to start working. The sex glands then signal other parts of your body to start to grow. These signals are carried by hormones. Hormones are made by your body to control its functions. They cause your body to change and start being more like an adult:

You might notice a change in your breasts first. They start to look as if the darker areas around the nipples (called the areolas) are swelling. The breasts also grow rounder and fuller. One breast may even seem a little larger than the other, and they may feel sore at times. This is normal.

After you go through puberty, your breasts will grow in stages. Stage 1 shows breasts before puberty. Stage 5 shows breasts that are fully developed.

Hormones also cause changes that prepare a girl’s body to be able to have a baby. The ovaries contain eggs, and when a girl matures, one egg is released each month. This is called ovulation. The egg then moves into one of the fallopian tubes. At the same time, the lining of tissue builds up in the uterus. If the egg has not been fertilized, the lining of the uterus is shed during menstruation (your menstrual period).

Female Reproductive System

Your Menstrual Period

There is no way to tell when you will have your first period. The average age is 12 years, but it can happen earlier or later. The first period is usually very light—only a few drops of blood. Periods usually last between 3 days and 7 days and happen about once a month. When you first start having periods, they may not be regular. There may be times when you miss a period. You may have two periods in 1 month. This is normal. It can take a while for your body to get on a regular pattern. However, if your periods are not regular 2 years after they begin or are extremely heavy or painful, talk to your doctor.

Keeping a Schedule

It is a good idea to use a calendar to keep track of your periods. Mark an “X” on the calendar on the first day your period starts. Count the first “X” as day 1. Keep counting the days until you have your next period. If you do this every month, you will be able to tell how many days there are between your periods. Some girls will have a period every 28 days. For others, it may be anywhere from 21 to 45 days during the first few years after their periods start. For some girls, it may change from month to month. Even when your periods start to be more regular, you may miss a period or be a few days early or late. If you have had sex, a missed period can be a sign that you are pregnant.

Keep track of your periods by marking an “X” on a calendar on the days when you have your period.

Be Prepared

It is best to plan ahead and be prepared for your period. Have pads or tampons ready at home and carry them with you to school. Pads are attached to the inside of your underwear. They absorb the blood as it leaves the vagina. Tampons are worn inside the vagina to catch the flow before it leaves the body. If you cannot decide whether to use a pad or tampon, talk with your mother, school nurse, or another adult you trust.

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

Do not leave a tampon in your vagina for more than 8 hours because that can lead to an infection called toxic shock syndrome. You also may want to avoid using scented tampons and pads because they can cause irritation.


Many girls have cramps (a feeling of tightness and pain) in the lower abdomen and back at the start of their menstrual periods. Some girls also get headaches, dizziness, diarrhea, or nausea. This is normal. To help ease cramps, you can:

Talk To Your Doctor

There are many reasons to talk to your doctor about your menstrual periods:

Looking and Feeling Your Best

The many changes your body goes through in puberty can sometimes make you feel awkward or uneasy. Taking care of your body will help you feel and look your best.

Eating Right

Your body needs nutrients to grow. Eating a balanced diet will help keep you healthy. Eat plenty of fruit and vegetables and drink lots of milk. Make sure to eat foods and drink fluids that contain plenty of calcium. You need at least 1,300 mg of calcium each day to build strong bones. Also, avoid eating too much fast food, which is loaded with fat and sugar.

Staying in Shape

To help keep your body in shape, you need to be active. Getting regular exercise can make your muscles and bones stronger and give you more energy. It also can help decrease menstrual cramps. Exercising can be fun if you find something that you like to do. Try a team sport such as soccer or basketball. Or try other activities, like riding a bike, dancing, walking, or running.

Dealing with Acne

Acne is caused by glands under the skin that produce a natural oil called sebum. Puberty makes these glands produce extra sebum, which can clog the pores in your skin. Washing your face often with water and mild cleanser usually helps get rid of the excess sebum in your pores. 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, there are medications that can help.


Puberty is a time of many changes. Everyone is different. Don’t worry if your body starts to develop before—or after—most of your friends. Remember, what you are feeling and going through happens to everyone.

Dealing with changes is a normal part of growing up. It is the start to the next exciting phase of your life. If you have questions, talk with an adult you trust—your parents, a doctor, a teacher, or a school counselor. You also can find books in the library that can answer your questions about puberty.


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

Menstruation: The blood and tissue that comes from the uterus each month when an egg is not fertilized (also called your period).

Ovaries: Two glands, located on either side of the uterus, that contain the eggs released at ovulation and produce hormones.

Puberty: The stage of life when the reproductive organs become functional and secondary sex characteristics develop.

Uterus: A muscular organ located in the female pelvis that contains and nourishes the developing fetus during pregnancy.

Vulva: The lips of the external female genitalia.

Source: acog.org