The diaphragm is a silicone cup with a firm ring attached to it. This cup is filled with spermicide and placed into your vagina before the act of sex. Now although it is an effective and safe form of birth control, you need to follow some very important steps in order for you to get the best contraceptive effectiveness from this form of birth control.
Again, the ring is a latex ring, and the cup is made of latex as well. You need to fill the cup with spermicide and carefully place it into your vagina far enough so that it covers your cervix. After your last act of sex, you need to keep the diaphragm in for at least four to six hours before you remove it. The logic behind that is so that the spermicide that is inside the cup will kill the sperm that may have leaked around the cup, before you remove it.
This requires a little bit of planning on the part of the user. The best time to place this diaphragm is not during the act of sex, because it can be very disruptive to fill the cup with spermicide and place it properly before you start having sex. And it's very important to remember to keep it in for long enough, because if you don't, the sperm can leak around the edges and go into your uterus and cause an undesired pregnancy.
This form of birth control with typical use is about 85 percent effective. It's a little less effective than condoms, and it requires a lot more motivation on the part of the user in order to gain the contraceptive effectiveness that you need.