Barrier birth control methods are forms of birth control that attempt to block passage of sperm into the uterus, so that the sperm cannot reach the fallopian tubes, fertilize an egg, and result in unintended pregnancy. All of these methods but one are intended for use by women. The only barrier birth control method for men is the male condom. Many barrier birth control methods also make use of spermicides. Spermicides decrease likelihood that an accidental escape of sperm will result in pregnancy.

The most effective barrier birth control methods are condoms intended for men and the intrauterine device (IUD). The former are made of latex and worn over the penis during all portions of intercourse. Condoms are also most effective in preventing the contraction of sexually transmitted diseases. A condom used properly is about 87-90% effective in preventing pregnancy. Used with spermicide, the condom proves about 92% effective.

Female condoms are relatively new forms of barrier birth control methods that are worn by the female sexual partner. When used properly, the female condom covers the interior of the vagina completely, thus blocking access to the cervix and uterus. Some women, however, do not like using this form because a portion of the condom can be seen outside the vagina. It is also less effective than the male condom and only about 79% effective in preventing pregnancy.

Two similar types of barrier birth control methods are the diaphragm and the cervical cap. Both methods require fitting by a gynecologist. The diaphragm had a spring-like ring backed by a thick layer of rubber, and it is filled with spermicide before being placed in the vagina. The cervical cap is also used with spermicide and fits over the cervix. Both the diaphragm and cervical cap are only worn during sex and a few hours before and after sexual intercourse.

Both of these barrier birth control methods can be less expensive over the long run than the female condom because they only need replacement about once yearly. Some women do have problems with the comfort factor of either of these methods. Occasionally women can also have allergies to spermicide, which makes wearing either of these barrier birth control methods difficult or impossible. The diaphragm and the cervical cap are both nearly equal to the female condom in effectiveness. The diaphragm is about 82% effective in preventing pregnancy, and the cervical cap has about an 80% effectiveness rate.

The IUD is the most permanent, and most effective of the barrier birth control methods. Many IUDS now release progesterone, which prevents a woman going through her normal menstrual cycle, lessening pregnancy. This form of birth control is intended for a woman who plans to be sexually active for a long time without getting pregnant, since unintended pregnancy with an IUD in place often means miscarriage of an unborn child.

Intrauterine means in the uterus; a gynecologist must implant an IUD device in a minor office procedure. The IUD may stay in place for 1-10 years, and has a 98-99% chance of preventing pregnancy. If the device proves uncomfortable, the procedure to remove an IUD is quite simple, but many women find IUDs infinitely preferable and more effective than other barrier birth control methods. It should be noted that IUDS, diaphragms, and cervical caps do not protect against STDs, and that no barrier birth control methods are completely effective in preventing pregnancy.