Condoms are safe and effective barriers against pregnancy and STIs, including HIV. Learn about the types, use, impact and WHO's work on condoms from this fact sheet. Wearing a condom during sex can help prevent pregnancy and the spread of sexually transmitted infections. Whether you're using a male or female condom , it's important that you put it on properly or it won't be as effective. Store condoms ... A condom can prevent pregnancy and reduce the risk of sexually transmitted infections. Find out about male and female condoms and how to use them. Condoms are very effective for preventing pregnancy and STDs, if used the right way. Find out about male and female condoms and how to use them.