• When used correctly, they are 92-96% effective
• You can put them in several hours before sex
• They protect against pregnancy but not sexually transmitted infections (STIs). To protect against STIs you will need to use  an additional method of contraception  such as condoms
• Diaphragms are made of thin, soft latex or silicone and have a flexible rim. Cervical caps are smaller and are made silicone (they used to be made of latex but newer caps are now made of silicone)

Most women are able to use a diaphragm. However, they may not be suitable for you if you:

• have an unusually shaped or positioned cervix (entrance to the womb), or if you cannot reach your cervix
• have weakened vaginal muscles (possibly as a result of giving birth) that cannot hold a diaphragm in place
• have ever had toxic shock syndrome
• have repeated urinary tract infections
• currently have a vaginal infection (wait until your infection clears before using a diaphragm or cap)

Research shows that spermicides which contain the chemical nonoxynol-9 do not protect against STIs and may even increase your risk of getting an infection.

A diaphragm may be less effective if:

• it is damaged – for example, it is torn or has holes
• it is not the right size for you
• you use it without spermicide
• you remove it too soon (less than six hours after the last time you had sex)
• you use oil-based products, such as baby lotion, bath oils, moisturiser or some vaginal medicines (for example, pessaries) with latex diaphragms – these can damage the latex

If any of these things happen, or you have had sex without contraception, you may need to use emergency contraception.