Abstinence is the only sure way to prevent pregnancy and sexually transmitted diseases (STDs).  Every other method of birth control carries some risk of both.

Teens who do decide to have sex have a variety of choices to reduce the risk of unwanted pregnancy.  Condoms are among the most popular methods of birth control, but if not used consistently and when used incorrectly they carry a relatively high risk of failure.  Latex condoms are the only form of protection that can stop transmission of HIV and can prevent pregnancy.  Other  means, including hormonal methods such as birth control pills, barrier methods like IUDs (intrauterine devices) or diaphragms and spermicides, require a visit to your health care provider.

Preventing STDs and pregnancies with birth control methods is a matter of accessibility, reliability, and proper use. Latex condoms are considered effective protection against STDs by reducing the likelihood of partner exposure through genital contact or fluid secretions. Because they are available at many stores and cost as little as 20 cents to $2.50, they are also easily obtainable. However, the chances of an unintended pregnancy or transmission of an STD depends largely on proper use. To be most effective, condoms must be used consistently and correctly. “Skin” or “natural” condoms may allow transmission of STDs, and polyurethane condoms are effective protection but not as widely available.

Oral sex is not necessarily safe sex. Receiving and giving oral sex can transmit STDs. Sexually transmitted diseases are mostly viruses or bacteria that enter the body through tiny cuts in your skin or mucus membranes during sex. Any form of sexual contact creates a chance of transmission. Herpes, gonorrhea, syphilis, hepatitis A, B, and C, and HIV all can be transmitted through oral sex.

Condoms and dental dams (a thin square of latex placed over the vagina) can help reduce the risk of getting an STD from oral sex.

Any sexual activity puts you at risk. The only way to be 100% free from risk of STDs is to not have sex. And youths are at high risk: Teens and young adults have the highest rates of STDs of any age group. In 2000, nearly half of the 19 million new STD cases occurred  among people ages 15-24.

About 35% of 14- to 19-year-olds are infected with human papilloma virus (HPV), the most common STD among teens. The HPV vaccine is recommended for girls ages 11 to 12, although it may be given to girls as young as age 9. Women up to age 26 should be vaccinated against strains of HPV associated with cervical cancer and genital warts.

About 18% of all new HIV diagnoses are among people aged 13-24.

Communication is an important part of sexual intimacy. For teens in particular, it’s important for sexual health and maturity. If you are in a relationship -- whether or not you are having sex -- you should talk to your partner about their sexual history for several reasons. It can help you establish sexual boundaries (whether you want to have sex or how far you’re willing to take the relationship sexually); it can help you learn if your partner has engaged in risky sex; and it can begin or continue a discussion about safe sex practices.

But talking can’t help determine whether your partner has an STD. Even if they assure you that they are sexually healthy, they may be infected with an STD and not know it. Three-fourths of women and half of men who are infected with chlamydia have no symptoms. “The only way to find out for sure if someone has an STD is to get tested,” says Bonnie Halpern-Felsher, PhD, professor of adolescent medicine and pediatrics at the University of California, San Francisco.

You don't need your parents' permission to make choices about birth control in most states. Minors are explicitly granted the right to contraceptive services in 21 states and Washington D.C.; four states have no specific policy; and the remaining 25 states explicitly allow the right to contraceptive services in certain circumstances.

Most health care providers will discuss your birth control needs and choices confidentially. Most family planning clinics keep visits confidential, and some provide free birth control. If you use your parents’ insurance, it will show up on their insurance statement.

When used consistently and correctly and used every time a couple has sex, the failure rate of latex male condoms is about 3%.

However, typical use -- incorrect and/or inconsistent use -- results in higher unintended pregnancy rates. Typical use, which is the average way they are used, results in a failure rate of 11% to 16%. This means that about 11-16 women per 100 can get pregnant during the first year of use. Condoms used in combination with other methods (birth control pills, IUDs, etc.) further reduce the risk of pregnancy.

Typical use of a female condom can result in unintended pregnancy rates of about 21%; 21 out of every 100 couples may get pregnant during the first year of use. Also under typical use, the rate of pregnancy for women who use a diaphragm and spermicide is 15%; used perfectly, it results in a failure rate of 9%. For those who use an intrauterine device (IUD), the failure rates are about the same, 1%.

When used consistently and correctly, birth control pills will result in an unintended pregnancy in less than 1% of cases.

However, under typical use, unintended pregnancies occur for about 5% of women. Typical use takes into account improper or inconsistent use. That means that over a year's time, about 5 out of 100 women who use this method will have an accidental pregnancy.

Birth control pills offer no protection against STDs.

Experts urge teens to talk with their parents or other trusted adults (a health care provider, for instance) about safe sex practices. Teenagers' peers can sometimes be an unreliable source of information -- or worse, a source of peer pressure. Parents or other grownups can help teens get accurate information about protection from STDs and unwanted pregnancies.

There may be another benefit of talking to your parents besides delaying sex: stronger relationships, says Halpern-Felsher. “Teens who preemptively talk to their parents about relationships and safe sex are more likely to have healthy relationships and less health risk,” according to Halpern-Felsher.

While unintended pregnancies are not a concern for gay or lesbian couples, safe sex practices are just as important due to the risk of STDs.  Abstinence is the only sure way to prevent STDs -- both for heterosexuals and for gay or lesbian couples.

Gay men or men who have sex with men are the group most severely affected by HIV. Accordingly, they are also the group that continues to see an increase in new cases annually. Because teens have a higher propensity for risky behavior, gay teens may be at particular risk.  Unprotected anal sex is considered a very risky behavior for transmission of HIV.

Lesbian and bisexual women can also transmit STDs to each other through sexual contact.  Chlamydia, bacterial vaginosis, genital herpes, and HPV can all be transmitted between women.