Abstinence is the only sure way to prevent pregnancy and STDs. Some sexual activities are much safer than others, though. Vaginal , anal or oral sex can spread any viruses, bacteria and parasites present in bodily fluids. Some activities may cause tiny tears in genital or rectal tissues. This allows bacteria and other organisms to penetrate the skin and cause infections.
Pregnancy is a risk, too, with unprotected intercourse.
Some types of HPV increase a woman's risk of cervical cancer or precancerous changes of the cervix , called cervical dysplasia . They are also at higher risk for bacterial vaginosis, which is an overgrowth of bacteria in the vagina . Latex and probably plastic male and female condoms protect best against STDs, because viruses and other organisms may slip through tiny holes in condoms made of animal skin. But no condom can offer complete protection. With male condoms, for example, skin surfaces like the scrotum and labia , or outer lips of the vagina may still touch.