If they’re fitted correctly and used perfectly every time you have sex, diaphragms and caps are 92% to 96% effective at preventing pregnancy when they’re used with spermicide (a substance that kills sperm).

This means that 4 to 8 users will get pregnant in one year.

If you don’t use your diaphragm or cap perfectly every time, they’re around 71% to 88% effective. This means that around 12 to 29 users will get pregnant in one year.

If 100 sexually active women don’t use any contraception, 80 to 90 will get pregnant in a year.

Diaphragms and cap covers your cervix (entrance to the uterus) to stop sperm reaching an egg. They’re most effective at preventing pregnancy when you also use spermicide.

A diaphragm or cap will be less effective if:

• it’s damaged
• it doesn’t cover your cervix completely
• it isn’t the right size
• you use it without spermicide
• you have sex three hours or more after you put it in and don’t use extra spermicide
• you don’t use extra spermicide with your diaphragm or cap every time you have sex
• you remove it too soon (less than six hours after the last time you had sex)

If any of these happen, or if you’ve had sex without using contraception, see below for emergency contraception.

Advantages

• You only have to use it when you have sex
• It has no serious health risks
• You’re in control of your contraception
• You can put it in before you have sex

Add extra spermicide if sex takes place more than three hours after putting it in.

Disadvantages

• You may find spermicide messy
• It can take time to learn how to use it
•  You may be sensitive to spermicide. This may cause irritation in you or a partner

Most people can use a diaphragm or cap. A diaphragm or cap may not suit you if you:

• have vaginal muscles which can’t hold a diaphragm in place
• have a cervix which is an unusual shape, in an awkward position or if you can’t reach it
• are sensitive to spermicide
• have repeated urinary infections
• have a vaginal infection (wait until after the infection has cleared)
• have ever had toxic shock syndrome
• don’t feel comfortable touching your vagina
• find it difficult to put in or place in the right position

If you have a high risk of getting a sexually transmitted infection (STI), for example if you or a partner has more than one partner, a diaphragm or cap may not be the best choice for you.

Diaphragms and caps don’t protect you from STIs and a chemical in spermicide called nonoxinol-9 may increase the risk of HIV infection.

Yes, but wait until at least six weeks after the birth. If you have sex earlier than this, use a different method of contraception.

You may need a different size diaphragm or cap after you’ve had a baby. Check this with your doctor or nurse.

Yes. If you used a diaphragm or cap before the miscarriage or abortion, check with your doctor or nurse that it still fits.

If you lost or gained more than 3kg, you may need a different size diaphragm or cap.

Talk to your doctor or nurse for more information.

You can get a diaphragm or cap from some contraception clinics, young people’s services and GP surgeries. It’s also possible to buy a diaphragm or cap online or from a pharmacy.

They come with instructions to help you learn to fit them, but it’s recommended that you also get advice on using them from a doctor or nurse.

Put your index finger (the finger next to your thumb) on top of the diaphragm. Squeeze the diaphragm between your thumb and other fingers.

Slide the diaphragm into your vagina upwards and backwards. This should ensure that the diaphragm covers your cervix.

You might squat, lie down, or stand with one foot up on a chair while putting your diaphragm in. Choose the position that’s easiest for you.

For the cap to be effective it needs to cover your cervix. It’s helpful to feel your cervix before inserting the cap (see How do I find my cervix? below).

Caps come with instructions and a doctor or nurse will show you how to put it in.The different types of cap are all used in a similar way.

Fill one-third of the cap with spermicide, but don’t put any spermicide around the rim as this will stop the cap from staying in place.

Caps have a groove between the dome and the rim; some spermicide should also be placed there.

Squeeze the sides of the cap together and hold it between your thumb and first two fingers.The cap must fit neatly over your cervix.

It stays in place by suction. Always check that your cervix is covered. Depending on the type of cap, you may need to add extra spermicide after it’s been put in.

You can find your cervix by inserting a clean finger into your vagina until you touch the top and can’t go any further.

The cervix feels like the end of your nose.

Leave your diaphragm or cap in for at least six hours after the last time you had sex. You can leave it for longer, but not for more than the recommended time.

For the diaphragm this is usually 24 hours. For the cap, this is usually 48 hours including the minimum six. Check the instructions for more information.

Take it out by gently hooking your finger under the rim, loop or strap and pulling downwards.

When you take your diaphragm or cap out:

• Wash it in warm water with a mild, unperfumed soap
• Rinse it thoroughly
• Dry it carefully and keep it in its container in a cool, dry place

Never boil your diaphragm or cap, never use disinfectant or detergent to clean it or use talcum powder with it.

Don’t use silicone-based or oil-based products or lubricants with a diaphragm or cap as these could damage it. Water-based lubricants are safe to use.

Check your diaphragm or cap regularly for tears or holes by holding it up to the light and having a good look at it. Be careful with your fingernails and jewellery.

If your diaphragm goes out of shape, squeeze it gently back into its circular shape. Your diaphragm or cap may become discoloured. Don’t worry, this won’t make it less effective.

Avoid using a diaphragm or cap during your period as it might increase your risk of getting an infection called toxic shock syndrome.

No. Water may dislodge it or wash away the spermicide.

Put your diaphragm or cap in after a bath, rather than before, and have a shower instead of a bath during the six hours after you’ve had sex, when you need to keep your diaphragm or cap in.

The effect of swimming or water sports hasn’t been studied, but it’s likely to be small.

Practising using your diaphragm or cap gives you time and privacy to find out if it’s suitable for you and to learn how to use it properly.

While you’re learning to use it, don’t rely on it to stop you getting pregnant. Use an additional method of contraception if you have sex.

Try putting the diaphragm or cap in and check that it covers your cervix. You can have sex with the diaphragm or cap in place and leave it in for a few hours to find out if it’s comfortable for you and a partner.

It’s also a good idea to use the spermicide to see how this feels.

If you want to get your diaphragm or cap checked by a doctor or nurse, wear the diaphragm or cap so the doctor or nurse can check that you’ve put it in properly and that it’s the right size.

Once you have a diaphragm or cap that you’re happy with, you only need to see a doctor or nurse to replace it or if you have any questions or concerns.

Check the fit of your diaphragm or cap with a doctor or nurse if you gain or lose more than 3kg (7lb) in weight, or if you’ve recently been pregnant. You may need a different size.