What Is It?

The diaphragm is a dome-shaped bowl made of thin, flexible rubber that sits over the cervix.

How Does It Work?

The diaphragm keeps sperm from entering the uterus by blocking the cervix. For added protection, spermicide is put into the bowl of the diaphragm and along its edges before inserting the diaphragm high into the vagina so it covers the cervix.

The diaphragm is inserted up to 6 hours before having sex. More spermicide must be used each time a girl has sex while wearing the diaphragm. Additional spermicide should also be used if a girl is going to have sex more than 3 hours after she inserted the diaphragm. After sex, the diaphragm must be left in for at least 6 hours, but no longer than 24 hours. The diaphragm can be removed by placing a finger into the vagina to pull it out.

Each time the diaphragm is removed, it must be washed (with mild soap and water), rinsed, and air dried, then stored in its case. It should not be dusted with baby powder and should never be used with oil-based lubricants such as mineral oil, petroleum jelly, or baby oil. These substances can cause the rubber to become brittle and crack. Other vaginal creams, such as yeast medicines, can also damage the rubber.

A diaphragm should be replaced at least every 2 years. It should be examined regularly for holes or weak spots, and replaced as needed.

How Well Does It Work?

Over the course of 1 year, 16 out of 100 typical couples who rely on the diaphragm with spermicide to prevent pregnancy will have an accidental pregnancy. In general, how well each type of birth control method works depends on a lot of things. In the case of a diaphragm, some of the most important things to be sure of are that it fits correctly, that is used every time a couple has sexual intercourse, and that spermicide is used appropriately.

Protection Against STIs

The diaphragm does not protect against sexually transmitted diseases (STDs). Couples having sex must always use condoms along with the diaphragm to protect against STDs.

Abstinence (not having sex) is the only method that always prevents pregnancy and STDs.

Possible Side Effects

Most women who use a diaphragm have no problems with it. The side effects that some women have include:

• Spermicides may irritate the vagina and surrounding skin or cause an allergic reaction.
• Strong odors or vaginal discharge may appear if the diaphragm is left in too long.
• The rubber or latex in the diaphragm may cause an allergic reaction (this is rare).
• Diaphragms and spermicides may make urinary tract infections more likely.
• Toxic shock syndrome (TSS) is a rare complication if the diaphragm is left in too long.

Who Uses It?

Girls who can take responsibility for sex in advance use diaphragms. If a girl chooses to use a diaphragm, she must also always have a supply of spermicide.

The diaphragm isn't good for anyone who is uncomfortable or uneasy with the thought of reaching into her vagina. And it may not be a good choice for girls with certain medical conditions, such as frequent urinary tract infections (UTIs). The diaphragm should not be used when a girl has her period.

How Do You Get It?

A doctor must fit a girl with a diaphragm. During a pelvic exam the doctor will measure a girl's vagina and then determine which size of diaphragm is right for her. The doctor or nurse will then teach her how to insert and remove the diaphragm. Some doctors may even ask a girl to practice at home and then come in while wearing the diaphragm to check that she has done it right. A diaphragm that's inserted incorrectly or does not fit properly can result in pregnancy.

During the annual exam, the doctor will check that the diaphragm still fits correctly. The diaphragm may not fit correctly if a girl has gained or lost 10 pounds, had a baby, had an abortion, or was fitted when she was a virgin and she is now having sex. If any of these things have changed since her last exam, a girl should see her doctor to have the fit of the diaphragm checked rather than waiting until her annual exam.

How Much Does It Cost?

A diaphragm usually costs about $15 to $75. It should be replaced every 2 years. There is also the cost of the doctor's visit and a fitting fee. Many health insurance plans cover these costs and family planning clinics (such as Planned Parenthood) charge much less. In addition, the cost of spermicide is about $0.50 to $1.50 per use.

Reviewed by: Larissa Hirsch, MD
Date reviewed: April 2010