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Barrier

Barrier contraceptives are devices that attempt to prevent pregnancy by physically preventing sperm from entering the uterus. They include male condoms, female condoms, cervical caps, diaphragms, and contraceptive sponges with spermicide.

Globally, condoms are the most common method of birth control. Male condoms are put on a man's erect penis and physically block ejaculated sperm from entering the body of a sexual partner. Modern condoms are most often made from latex, but some are made from other materials such as polyurethane, or lamb's intestine. Female condoms are also available, most often made of nitrile, latex or polyurethane. Male condoms have the advantage of being inexpensive, easy to use, and have few adverse effects. Making condoms available to teenagers does not appear to affect the age of onset of sexual activity or its frequency. In Japan, about 80% of couples who are using birth control use condoms, while in Germany this number is about 25%, and in the United States it is 18%.

Male condoms and the diaphragm with spermicide have typical use first-year failure rates of 18% and 12%, respectively. With perfect use condoms are more effective with a 2% first-year failure rate versus a 6% first-year rate with the diaphragm. Condoms have the additional benefit of helping to prevent the spread of some sexually transmitted infections such as HIV/AIDS, however, condoms made from animal intestine do not.

Contraceptive sponges combine a barrier with a spermicide. Like diaphragms, they are inserted vaginally before intercourse and must be placed over the cervix to be effective. Typical failure rates during the first year depend on whether or not a woman has previously given birth, being 24% in those who have and 12% in those who have not. The sponge can be inserted up to 24 hours before intercourse and must be left in place for at least six hours afterward. Allergic reactions and more severe adverse effects such as toxic shock syndrome have been reported.