Mechanical methods of birth control, also know as barrier methods, are among the most common forms of contraception. Some of them, like condoms, are also the only methods that also reduce the risk of sexually transmitted diseases and HIV. All mechanical methods of birth control rely on preventing sperm and egg from meeting. Despite the same premise, there are several different forms of mechanical birth control, with different characteristics.
When used correctly, traditional condoms are 85 per cent to 98 per cent effective in preventing pregnancy. They must be used consistently and correctly to achieve such efficacy. According to the Centers for Disease Control and Prevention (CDC), in addition to contraception, condoms are also capable of greatly reducing the risk of STDs and HIV. They are less effective against STDs that can be spread through skin-to-skin contact such as genital herpes and HPV, but they still reduce the risk of these infection compared to unprotected sex.
Female condoms are designed to be inserted inside the vagina. They can reduce the risk of pregnancy by 79 per cent to 95 per cent and, per the CDC, "may also prevent STDs." They are usually packaged with a small amount of lubricant to aid in insertion, and they can be inserted up to eight hours before sex.
Like the female condom, cervical caps or diaphragms are intended to be inserted inside the vagina. In this case, they fit over the cervix --- the opening to the uterus --- and block sperm. They must be worn inside the vagina for up to eight hours after sex. Combining them with spermicide can improve effectiveness. Their efficacy rate is 84 per cent to 94 per cent at preventing pregnancy with no STD protection.
Spermicides are chemicals designed to kill sperm and prevent pregnancy. They are placed directly into the vagina, and they come in gels, dissolving film, expanding foam and tablet forms. They should be inserted no more than an hour before sex and not removed less than eight hours after sex. Spermicides can be combined with other barrier methods to increase their effectiveness.