This means methods of contraception that not only prevent a pregnancy but also protect against infection spread by sexual intercourse. Combined contraceptive pills can prevent a pregnancy but cannot protect you from sexually transmitted diseases (STDs) and AIDS. Condoms give some protection from infection as they are placed on the penis and stop it from touching the vagina directly. Using a condom greatly reduces the chances of getting an STD. However, it is still possible to get infected in areas not covered by a condom. The best way to avoid infection by an STD is to avoid having sex with someone who might have an STD.