Topic Overview

The diaphragm is a barrier method of birth control. It is a round, dome-shaped device made of rubber that has a firm, flexible rim. It fits inside a woman’s vagina and covers the cervix. It should always be used with a sperm-killing cream or jelly (spermicide). There are different types of diaphragms:

• The flat-spring and coil-spring types can be used with an inserter.
• The arcing-spring type is easy to insert with the fingers.

A woman inserts her diaphragm no sooner than 6 hours before having sexual intercourse. To be effective, it must be used with a spermicide. The diaphragm must be left in place for 6 hours after intercourse and can be left in place up to 24 hours.

Prescription method

The type of diaphragm that works best for you will depend on your vaginal muscle tone and the shape of your pelvis. Diaphragms come in different sizes, so you must visit a health professional to be fitted and get a prescription for the right size and type of diaphragm. At this visit, you will be taught how to use and care for the diaphragm. A return visit with the diaphragm already in place is usually needed to be certain that you are using it correctly.

You will need to be refitted for the right size of diaphragm after:

• Pregnancy. Pregnancy and childbirth can change the size of the cervix or vagina.
• Major weight gain or loss.

A small weight gain or loss or a therapeutic abortion usually does not require a new diaphragm size.

Replace your diaphragm every 1 to 2 years to avoid an unintended pregnancy. With time and repeated use, small holes can form in the rubber. Rubber can also weaken over time and tear more easily.

Effectiveness in preventing pregnancy

On average, the diaphragm user failure rate is 12%. This means that 12 women out of 100 become pregnant in the first year of typical use. Not using the diaphragm with every act of intercourse is the most common reason for failure. The “perfect use” failure rate is 6%, with a pregnancy in 6 out of 100 women who carefully use the diaphragm every time they have sex.^{footnote 1}

Effectiveness in preventing sexually transmitted infections (STIs)

Diaphragms do not fully protect against sexually transmitted infections (STIs), including infection with the human immunodeficiency virus (HIV). Also, the use of spermicides with nonoxynol-9 may increase your risk of getting HIV/AIDS. So be sure to use a condom for STI protection unless you know that you and your partner are infection-free.

Advantages of the diaphragm

• It does not affect future fertility for either the woman or the man.
• It is used only at the time of sexual intercourse.
• It is safe to use while breastfeeding.
• It is less expensive than hormonal methods of birth control.
• It can be used by women who have health problems that would make estrogen use dangerous, and by women who smoke.

Disadvantages of the diaphragm

Failure rates for barrier methods are higher than for most other methods of birth control.

• The diaphragm should not be used by women who have ever had toxic shock syndrome.
• Women who use diaphragms may get more bladder infections (urinary tract infections, or UTIs). This is probably because the rim of the diaphragm presses on the urethra and may irritate it. A woman who gets frequent UTIs may need a smaller diaphragm or may prefer not to use the diaphragm.
• Some people are embarrassed to use this method or feel the method interrupts foreplay or intercourse.
• A couple must be comfortable with using the diaphragm and be prepared to use it every time they have sex.
• A diaphragm can’t be used if either person is allergic to latex.

It is important to check your diaphragm for any cracks, holes, or other damage that would reduce its effectiveness. Do not use any petroleum-based vaginal creams, oils, or ointments, which can damage the rubber. But water-based personal lubricants, such as Astroglide and K-Y Jelly, are safe to use.