Teen Health Health Topics

Your body is changing; your moods may be unpredictable and sometimes hard to explain. Don't worry. These changes are normal.

Both boys and girls go through many changes during the teenage years. And while changes in girls are different than those experienced by boys, all of these changes are a natural part of your development into an adult. These changes are called puberty.
Puberty—How Your Body Changes

Puberty lasts for several years and marks the life stage when your body is changing from a child to an adult. Hormones help trigger and guide this process. Hormones are natural chemicals in your body that produce gradual physical changes during this time and may also cause emotional changes that can sometimes seem uncontrollable. These changes are common during puberty, and they happen to everyone. Although it may seem that these changes and feelings are out of your control, don't worry—you're still you, just the "growing up" version.

Girls, one of the first changes you will notice are your breasts growing, usually between the ages of eight and 12. Sometimes one breast grows larger than the other. Don't worry—they will most likely even out. Just like your ears, they aren't always a perfect match. Once your breasts start growing, you will most likely want to buy a bra. (See under Resources, "Checklist for choosing a bra.")

Another change you will notice is hair growth. Hair will grow under your arms, on your legs and on your pubic area. Shaving your underarms and legs is a personal choice. Some women do; others don't. If you decide to shave, make sure you use your own razor. Don't share razors with friends. And use either shaving cream or soap and water as a lubricant for shaving. If you want to shave, talk about it with one of your parents first. (See Resources, "Shaving: Do's and Don'ts.")

A less noticeable change is the widening of your hips and the slimming of your waist. Your stomach, bottom and legs might change shape, too. All of these changes are making you look more like a woman than a girl, and they are all normal, expected changes.

Another sign of puberty could be all over your face. It's called acne (otherwise known as pimples, or "zits"). This aggravating condition may be mild (blackheads and whiteheads), moderate (larger inflamed-looking blemishes) or severe (large cysts or nodules). Greasy foods and dirt do not cause acne; acne is caused by a build-up of oil, microorganisms and dead skin cells in the hair follicles under the skin. When whiteheads rupture (from squeezing, picking or hard scrubbing), the content spills over and causes inflammation and more acne in the surrounding tissue.. Keeping your face clean is one way to combat acne. Also, don't squeeze pimples. This can make them much worse and increase the chance of scarring. Often the condition of your skin during puberty will be similar to what your parents experienced when they were teenagers. If your acne concerns you, talk to your parents and/or a health care professional. The condition can be treated. (See Resources, "Myths and Facts about Acne.")
Your Menstrual Period

The most significant change during puberty for many girls is their first period. Menstruation is a turning point in your development from a child to a teenager. Among other things, it means you are capable of becoming pregnant. Your first period can be unexpected. You might be surprised to find that you have some bleeding from your vagina. Many young women might feel frightened by the sight of this bleeding or embarrassed if it causes a stain on their underwear or clothing. It's important to remember that this is natural and something that makes being a woman special. You can avoid embarrassing situations by talking to your mom or another adult (dads know about these things, too!) about being prepared for your period.

Your first period is likely to occur between the ages of nine and 16. It usually lasts for three to seven days and then stops until the next period begins—usually about 21 to 28 days after your period started. This timeframe—from the first day you begin to bleed until the first day of your NEXT menstrual period—is called your "menstrual cycle."

During your menstrual cycle, one of your two ovaries releases one microscopic egg, called an ovum. (Your ovaries are reproductive organs approximately one and a half inches long and located in your lower abdomen, one on each side of your uterus; ovaries also release hormones that help to control your menstrual cycle.) The egg's release from the ovary is called "ovulation," and it usually happens in the middle of your cycle—around day 12 to 14 in a 28-day cycle. Ovulation can be irregular, though, when you first start having your period.

The egg then moves through one of the two fallopian tubes (the two tubes attached to the top of the uterus that lead to the ovaries). At the same time, body tissues and blood cells are beginning to line the walls of your uterus, forming a thin layer of material that will eventually be shed as your period. The amazing thing is, you won't feel any of this happening
If you were to have sexual intercourse at this time (around the time of ovulation), and sperm from a male partner would fertilize your egg on its way to the uterus, you would become pregnant. The egg would attach to the lining of the uterus and a fetus would grow inside of you. However, if sperm does not fertilize the egg, your body does not need this lining to support the fertilized egg. So, hormones trigger a different process, and this lining gently falls away from the walls of your uterus and is released from your body through your vagina. This is often called the menstrual flow or period.