Also, of course, a
latex disc around a
spring steel ring that is used as a
barrier method of
contraception, usually augmented with the application of a
spermicide.
The diaphragm can be extremely effective if used conscientously and correctly, and if the diaphragm is fitted correctly. The diaphragm has to completely cover the cervix, and has to be prescribed and fitted by a medical professional. If the woman gains or loses more than 10 pounds, or becomes pregnant, the diaphragm must be refitted.
Diaphragms have about an 85% success rate at preventing pregnancy--largely due to some specific things that have to be done when it is used. It can be inserted 2 to 3 hours before intercourse, but must be left in 6 to 8 hours afterwards to be sure the spermicide is effective. If you have intercourse again in that period additional spermicide must be applied with an applicator. Diaphragms will become ineffective after a few years and should be replaced regularly. Every time it is used it should be checked for tears or pinholes (since it is natural latex, there can be flaws which can cause holes). If the diaphragm is not inserted correctly, it is possible that the penis will get behind it, and possibly cause it to be ineffective (and painful for both parties).
Some women (and men) may become sensitive to the spermicide or latex in diaphragms, just like you might with a condom.
The chief advantages to the diaphragm is that it is a temporary form of birth control, has a lower risk of side effects than the Pill, and somewhat reduces the risk of STDs. It's main disadvantages is that it completely wrecks spontaneity.