Puberty for Girls

Puberty is the time when a girl's body grows into a woman's body. The physical changes are necessary for a girl to reproduce (have babies) later in life. There is also the emotional part of puberty when a young person becomes an adult.

How does puberty start?

Hormones are responsible for changes in your body. Hormones released from your brain, cause your ovaries (organs that hold eggs) to produce estrogen. Estrogen is the main hormone that starts the body changes.

When does puberty begin?

Puberty may begin as early as 7 or 8 years old or as late as 14 years old.

How do I know if puberty has started?

The first thing you will notice will be growth of your breasts. At first, the gland just below the nipple starts to get bigger. This is called breast budding. This change means that the estrogen has started to work and the process of puberty has begun. It may take 4 or 5 years for your breasts to fully develop. You may want to start wearing a bra once your breasts start growing.

What happens to the rest of the body?

Pubic hair starts to grow soon after the breasts start to develop. Pubic hair grows to form a triangle-like pattern. Underarm and leg hair will also begin to grow.

A girl's body also starts to change shape. Your hips get wider and body fat moves to new places on your body. These changes prepare a woman to be able to deliver and support a baby after birth. Sometimes girls have trouble accepting their changing body shape - that's OK, but understand that it is important for your health and a normal part of growing up. Also, you will gain weight throughout adolescence. This is normal. If you are concerned, talk with your healthcare provider about it.

Many changes take place inside your body, too. The cells lining the vagina begin to change and quickly replace old cells. This creates a small amount of white discharge from your vagina. This is normal. The vagina gets bigger as well. Take the time to look at your genitals and notice the changes (you may need to use a mirror to see). The uterus also gets bigger (this is the organ in the body where babies grow). Inside the uterus, blood vessels and tissue begin to develop, eventually leading to your first period and the start of your menstrual cycle.

What is a menstrual cycle?

Girls are born with all their eggs (about 2000 or so), which are stored in the ovaries. Once puberty has begun, the hormones signal the ovaries to start developing the eggs. After puberty, an egg fully develops and is released from an ovary about once a month. This is called ovulation. The egg travels through the fallopian tube into the uterus. Two hormones (estrogen and progesterone) cause the lining of the uterus to thicken. The lining thickens to get the uterus ready just in case the egg is fertilized.

When an egg is fertilized, it grows into a baby in the uterus. If a man's sperm does not fertilize the egg, hormone levels go down. This signals the uterus to shed the lining it prepared for a baby. When the uterus sheds its lining, blood flows out of your vagina. This is called menstrual flow, or your period. After your period, the monthly cycle begins again. The entire menstrual cycle takes 22 to 35 days.

What else should I know about periods?

Periods come at the end of your monthly menstrual cycle and last 3 to 7 days. You will need to use pads or tampons to help absorb the blood that comes out. Though it sometimes seems like a lot of blood, it is usually only about 2 to 5 tablespoons over the entire period. For the first year or two, your periods are usually irregular. That means they can happen anywhere from once a month to 3 times a year. Periods start coming on a regular schedule once your body starts releasing eggs (ovulation). Ovulation usually begins 1 to 2 years after your period starts, but can happen with your first period.

It is always good to carry an extra tampon or pad with you in case your period starts unexpectedly. Often a girl's first period happens about 2 and 1/2 years after her breasts start developing. The average age for a girl's period to start is 12 and 1/2 years old. Some girls start their periods as early as age 10 or as late as 16. If you get your period earlier than 10 or still haven't had a period after age 16, then you should talk to an adult or your doctor about it.

What are cramps?

Some girls have lower abdominal pain and cramping during ovulation or during their period. The pain can be mild or severe. If it happens before your period starts, the pain is caused by ovulation and usually lasts a short time. Cramps most often happen during your period. They are caused by the chemicals that cause shedding of the lining of your uterus. You may have pain for only a day or it may last for your entire period. Taking ibuprofen (Advil) usually helps. If it doesn't help, ask your doctor about stronger medicine.

What is masturbation?

During puberty girls sometimes start to recognize sexual feelings because of the increase in hormones in their bodies. Often, girls discover that touching or rubbing their genital area feels good. This is called masturbation. Many girls masturbate during adolescence. It is a normal activity, even though it is not commonly talked about.

What are growth spurts?

Another important part of puberty is having a growth spurt and developing strong bones. A growth spurt is when your body grows a lot in a short period of time. A girl usually has her growth spurt 1 to 2 years after puberty starts. Once your period begins, you usually do not grow much taller. However, your bones continue to get stronger. Girls add 40% of their bone once puberty begins. Your bones continue to get stronger until about age 18 to 20. This is why it is very important for you to have 4 to 5 servings of food containing calcium (milk, yogurt, etc.) every day. This is the chance for your bones to get as strong as possible, so you have less of a chance of developing osteoporosis (weak bones) when you are older.

What about acne?

One part of puberty that teenagers don't like is acne. It is a normal part of growing up caused by your changing hormones. For some girls, acne may be mild, but for others it may get pretty bad. Using nonprescription medicine is OK if your acne is mild, but if it seems to be more serious, see your doctor. A doctor can give you stronger medicine to help the problem.

What are the emotional changes of puberty?

Puberty and adolescence is a complex time. As you go through the physical changes of puberty you start to experience a wide range of feelings. You are trying to figure out your place in the world. You become more independent and start doing things without your parents. You may be influenced by your friends' ideas and feel pressure to do things that you may not agree with, like using drugs or alcohol. It is a time to start sorting out your values and decide what is right and wrong.

As part of this, you may start to have strong sexual urges. You may develop a romantic attraction to someone and begin dating. You may feel like you are in love one day and not the next. It is natural to have changing feelings. You may also decide to become intimate with others. Intimacy can include many things. You can be intimate holding hands, hugging, or kissing.

When you become a teenager, you may also start thinking about having sex. Take time to think through your decision before you have sex. You need to think about the physical and emotional risks you will be taking. If you decide to have sex (intercourse) or oral sex (kissing a partner's genitals) it is important to be able to talk with your partner about what you are doing and the risks involved. Sexually transmitted diseases and pregnancy may be a consequence of having sex. The only way to prevent pregnancy 100% of the time is to not have sex. You need to decide what you are comfortable doing and be safe.

If you decide to have sex, talk to your health care provider and begin taking a hormonal type of birth control (such as, the pill, the patch, or Depo-Provera) before you have sex for the first time. You also need to use condoms to prevent sexually transmitted infections.

Talking to Parents:

Sometimes during puberty, teenagers may feel distanced from their parents. Parents may feel the same way and may be uncomfortable talking with their teenager about intimate issues. You need to understand that your culture, music, and clothing styles are different than what your parents are used to. Your parents may not feel in touch with your world, but they really want to understand what you are going through. Try to let them into your life and explain to them what you like and don't like. Be open when they make an effort to talk with you about personal things such as sex, drugs, and friendships. It can be just as hard for parents to discuss these topics as it is for you. If you feel like your parents are not meeting your needs, talk to them about it and ask them if you can spend time together. Deep down, they truly want the best for you. Parents are ultimately your best resource and strongest support. Give them a chance!

This handout is only a brief introduction to puberty. There are much more detailed books and pamphlets available to help you understand both the physical and emotional changes you may be going through. You are encouraged to find out as much as possible. Read books, talk to parents, friends, and teachers, or check the World-Wide Web to find resources to help you figure out this dynamic time of your life. One helpful Web site is The Center for Young Women's Health, http://www.youngwomenshealth.org

Written by B.D. Schmitt, MD, author of "Your Child's Health," Bantam Books.
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.