How Condoms Actually Prevent Pregnancy—and More

The barrier method is a go-to for many couples.

Arguably the most convenient birth control method is the barrier method. Although new methods with long lifespans and high effectiveness come along, barrier methods like the classic condom are simply too convenient to be ignored. They typically do not require a prescription and are easily affordable for most couples. Condoms also happen to be the only form (well, besides abstinence) that protects against sexually transmitted diseases.

Barrier contraceptives get their name from the literal barrier they create between the sperm and the egg. Pregnancy is prevented because sperm cannot reach the egg. Most of us are familiar with the male condom, but the diaphragm, the sponge, and the shield are all types of barrier contraceptives for women. Female barrier devices require a spermicide, which is a gel, cream, or foam that inhibits the movement of sperm.

Although female barrier devices exist, the most common barrier method is the condom. When used correctly, the male condom is 89% effective and the female condom is 79% effective. They are also the only method to prevent sexually transmitted diseases like human papillomavirus (HPV) or human immunodeficiency virus (HIV). Condoms are convenient, but they do have drawbacks: they are disposable after one use (which means you have to buy replacements often), they can tear, and they are usually made from latex, a common allergen.   

The diaphragm is a small disk that you insert into the vagina and fit over the cervix. (Here’s more information on the female reproductive system.) The diaphragm must be left in place for six to eight hours after sex. As with condoms, diaphragms are a no-go for those with latex allergies, and they also have a risk of toxic shock syndrom and vaginal and urinary tract infection. A perk of the diaphragm is that it is reusable for one to two years with proper care.

The sponge and the shield work similarly as the diaphragm but are over the counter. They are also inserted into the vagina, work with a spermicide, and must be left in place for six to eight hours after sex to ensure protection. The shield is reusable for up to six months, can be left in place for up to 48 hours, and is 85% effective when used correctly. The sponge is disposable after one use and is 84% effective.

Talk to your doctor and partner when deciding which is best for you. You may also want to consider other methods, such as the pill or an intrauterine device (IUD), which the FDA label as 99 percent effective. You can also use these hormonal contraceptives in conjunction with a condom to prevent both pregnancy and STDs.

Isabel Blumberg, MD

This video features Isabel Blumberg, MD. Dr. Blumberg is a clinical instructor of obstetrics, gynecology, and reproductive science.

Duration: 3:51. Last Updated On: June 7, 2018, 2:07 p.m.
Reviewed by: Suzanne Friedman, MD, Preeti Parikh, MD . Review date: June 30, 2017
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