During adolescence, your body is going through many changes that are happening at a fast pace. While these changes might make you feel unsure of yourself at times, they can also be exciting. You are becoming a young woman! Learning about what is going on with your body will help you get through these changes.

This time in your life when your body is changing is called puberty. For girls, puberty usually starts between the ages of 9 and 16. Sometimes, it can start as early as 6 or 7. Puberty for boys usually starts between the ages of 13 and 15, but may start as early as age 9. For both girls and boys, puberty takes several years. Major body changes have taken place for most girls – but not all – by the time they are 14. For boys, these changes happen at age 15 or 16. The first sign of puberty for most girls is growing breasts. Other changes include new body hair, different body shape, and getting your period. The changes in your hormones that cause you to get your period make you able to get pregnant and have a baby.

Source: 4girls.gov & 4Girls Health

Most menstrual periods last from three to five days, but anywhere from two to seven days is normal. The amount of blood flow varies, too, but for most women, bleeding starts out light at first, followed by heavier flow for a day or two and then another light day or two. Sanitary pads or tampons, which are made of cotton or another absorbent material, are worn to absorb the blood flow. Sanitary pads are placed inside the panties; tampons are inserted into the vagina.

"The amount of bleeding varies from woman to woman because everybody's body has a different way of building up the lining of the uterus," says Lisa Rarick, M.D. "A lighter flow or heavier flow doesn't mean you can't get pregnant as easily or you're never going to get pregnant, or that your periods will always stay the same way. But if you're bleeding excessively-soaking one or more tampons or pads an hour-you should see a doctor to see if there's a problem."

Rarick, a gynecologist with FDA's Center for Drug Evaluation and Research, says teenagers often are concerned if they expel blood clots during their periods. She says this is not dangerous; they are clumps of pooled blood in the vagina. Sometimes, instead of flowing freely, blood drains from the uterus and stays in the vagina until there's a change in position--say, from sitting to standing.

Women who use tampons should be aware of toxic shock syndrome, or TSS, a rare but serious-and sometimes fatal-disease that's been associated with tampon use. Tampon packages carry information about TSS on the box or inside. Because TSS mostly affects 15- to 19-year-olds, it's especially important for teenagers to know what signs to look for. If you develop the following symptoms while menstruating, remove the tampon and get medical help right away:

• sudden fever over 102 degrees Fahrenheit
• vomiting
• diarrhea
• dizziness, fainting, or near fainting when standing up
• a rash that looks like a sunburn.

Source: FDA/Office of Public Affairs