How Does Contraceptive Foam Work?

About Contraceptive Foam

Contraceptive foam is an agent that is inserted into the vagina to prevent conception. There are different methods of application and the foam may be used with other forms of birth control, such as a diaphragm, or on its own. The foam may come in aerosol form, as a suppository or impregnated in a sponge. Contraceptive foam works in two ways: by affecting the sperm's motility and by killing the sperm with a spermicide.

Motility Prevention

Contraceptive foam acts as a barrier, trapping sperm as it is ejaculated into the vagina. Sperm are strong swimmers, but the added viscosity of the foam slows them down. It is important to insert the foam no more than 20 minutes before intercourse. Wait any longer and the foam may dissolve and won't trap sperm as effectively.

Spermicide

The foam also contains a chemical, nonoxynol-9, that kills sperm before they can reach the egg. Using contraceptive foam with another barrier method, like condoms or a diaphragm, adds an extra measure of protection---any sperm the barrier misses will be killed by the spermicide. Again, because the foam does disperse, over time, it is crucial that you apply the foam shortly before intercourse.

Effectiveness

While no birth control method is 100 percent fool-proof, when used properly, contraceptive foams alone are about 80 percent effective. When used in conjunction with condoms, diaphragms and other barrier methods, contraceptive foams can be as much as 95 percent effective. Improper use of the product significantly reduces the level of protection.

Advantages and Disadvantages

One of the biggest advantages to contraceptive foams is that they are readily available and you only need to use them when you are having sex. When used with latex condoms, they significantly reduce the risk of catching sexually transmitted diseases. One of the biggest downsides to contraceptive foams is that they are not always convenient to use. You have to make sure to get the foam deep into the vagina, against the cervix and the foam is only affective 10 minutes to one hour after insertion. If you have not had intercourse or ejaculation after an hour, you need to insert more product and wait another 10 minutes. Nonoxynol-9 is also known to cause rashes and irritation and some women don't like the leakage that occurs after, when the excess foam leaves the body.