Risk factors for sexually transmitted diseases (STDs) include:

• Having unprotected sex. People who do not use condoms have a higher risk of getting an STD.
• Being sexually active at an early age. Sexual activity before age 18 may increase the risk of getting an STD, because teens may have more sex partners or they may be less likely to use condoms to reduce their risk. Girls younger than 18 get STDs 2 to 3 times more often than those older than 18. The cells of the transformation zone of the cervix are more susceptible to infection in teen girls.
• Having more than one sex partner.
• Having a high-risk sex partner (one who has other sex partners).
• Participating in prostitution.
• Using birth control pills without using condoms.