Are you ready for sex? Deciding when to engage or not engage in sexual relations is one of the most important decisions a person, of any age, can make. Some girls you know may already be sexually active. About 42 percent of all high school girls are having sex, according to a 2001 study by the U.S. Centers for Disease Control and Prevention (CDC). It is a decision that could affect the rest of your life. Take it seriously and know the risks, from getting pregnant to contracting a sexually transmitted disease, not to mention other emotional and physical risks that can come into play when teenagers have sex.

If you are sexually active, you can use one or more types of birth control to prevent getting pregnant. You can also lower your risk of contracting an STD by using condoms. No method, however, is 100 percent safe. The only foolproof way to keep from getting pregnant or avoid an STD is not to have sex.

Sexually Transmitted Diseases (STDs)
STDs are spread by sexual intercourse or genital contact. You can contract an STD from having oral sex with an infected partner. Almost four million cases of sexually transmitted diseases occur among teenagers every year, according to the CDC.

You may have heard about some STDs, such as HIV/AIDS, gonorrhea and herpes. But there are many other STDs to know about, so read on.

You are most likely to get an STD during your teen and young adult years — more than two-thirds of all STDs occur in people younger than 25. Because STDs often cause no symptoms (especially in girls and women), health care professionals recommend that sexually active girls and women routinely be tested or screened for STDs. If you are too embarrassed to talk to your health care professional, discuss the issue with a school nurse or call your local health department, Planned Parenthood or the U.S. Centers for Disease Control and Prevention's STD hotline.

Treating some STDs is often a snap — just antibiotics — but the health consequences of an STD remaining untreated can be severe. And, the most common STDs, human papillomavirus (HPV) and herpes, are viral diseases that can't be cured. The longer you have an infection without treatment the more damage it can do, including causing permanent damage to your reproductive organs, making pregnancy later in life difficult. Some STDs can cause problems during pregnancy or during a delivery.