Diaphragm and cervical cap effectiveness

Originally Published: March 9, 1995 - Last Updated / Reviewed On: November 14, 2014
Share this
Dear Alice,

How effective is the diaphragm? I was on the pill, but it made me ill and depressed. However, I miss the spontaneity and reliability of it. What about the cervical cap?

Signed,
Just Say No to Hormones

Dear Just Say No to Hormones,

It’s not uncommon for a woman to try a few different methods of birth control before finding one that fits her lifestyle and has few, if any, undesirable effects. Rather than using hormones to regulate a women’s fertility, the diaphragm and cervical cap are barrier methods of contraception that work by physically blocking sperm from entering the cervical opening. They are designed to be used with spermicidal jelly or cream, creating a double form of contraception: physical and chemical. As far as effectiveness is concerned, using these methods correctly and consistently each time you have sex is key. When a diaphragm used correctly and consistently, the effectiveness rate is fairly high and is upwards of 94 percent. The effectiveness rate of the cervical cap ranges from 71 to 86 percent, depending on if the woman has previously given birth (more on that in a bit). Though these methods may be an effective alternative for pregnancy prevention without the use of hormones, knowing a bit more information will help you decide whether or not either of these methods would be best for you. 

Here are a few things to know about using a diaphragm or cervical cap:

  • Both methods will require a visit to your health care provider to get a proper fit. During this fitting, your provider will also teach you how to insert and remove the method of your choice. It's a good idea to practice taking it in and out a few times before you leave the office. Just for a point of reference, the diaphragm is the larger of the two methods (though designed to fit comfortably in the vagina) and is shaped like a shallow dome or cup. The cervical cap is a bit smaller and looks more like a small sailor hat.
  • Both require insertion of the device before sex and the use of spermicidal jellies or creams. The spermicide is applied on the inside the diaphragm and on both sides of the cervical cap. Both must be left in place for six hours after sex. If you have sex for a second time and plan on using a diaphragm, make sure to add a bit more spermicide prior to the next round. Both devices can also be left in for a period of time after sex. The diaphragm can be left in for up to 24 hours and the cervical cap can be left in for up to 48 hours (e.g., you could put it in on a Friday night and leave it in through Sunday evening). Leaving either in for a longer period of time than indicated may increase the risk for toxic shock syndrome (TSS).

There are a few additional considerations that may impact your choice to use either device:

  • Allergies and sensitivity to spermicides and latex may be of concern with these methods. Some people experience irritation when using spermicides.The irritation caused by spermicides may also increase the risk of infection, including urinary tract infections (UTIs) and HIV. If you’re sensitive to spermicide or have previously experienced irritation due to using it, diaphragms and cervical caps may not be the best choice for you. Also, if you have a latex allergy, you may need to avoid these devices or see if there is a non-latex version available.
  • Getting the proper fit is crucial to pregnancy prevention effectiveness rates. Any time you experience weight gain or loss (by about 15 pounds in either direction) or a pregnancy when using a diaphragm, you’ll need to be refitted for the method. The cervical cap is less effective for women who’ve given birth vaginally and only comes in a limited number of sizes.
  • These methods do not provide protection against sexually transmitted infections (STIs). If STIs are a concern for you, you’ll want to look into using an additional method of protection, such as female or male condoms, to reduce your risk.

A quick note on the depression you mentioned while on the pill: It’s always a good idea to speak with your health care provider about any undesirable side effects you’re experiencing when using birth control. S/he will be able to discuss this with you as well as your desire for a method that is reliable and allows for spontaneity. Doing this will help you to determine what form of contraception will be the best fit. Best of luck!

Alice

For more information or to make an appointment, check out these recommended resources:

Medical Services (Morningside)

Student Health Service (CUMC)