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Contraception » Diaphragm / Cap

Diaphragm / Cap

How effective is it?

92-96% effective
4-8 women in 100 will get pregnant a year.

How does it work?

The diaphragm / cap is a flexible dome made of rubber or silicone, which is covered with spermicide gel and put into the vagina to cover the cervix (the entrance to the womb). It prevents sperm from entering the womb and meeting an egg. Sex should occur within three hours of insertion and it must be left in place for at least six hours after intercourse.

Possible Side Effects

Advantages / Benefits


Who can provide it?

Sexual Health Services or GP.
Caya (the silicone diaphragm) can be bought online


Diaphragm / cap size must be checked every 6-12 months or if there is weight gain or loss more than 3Kg (7lb).
Diaphragm /cap must be checked after miscarriage, abortion or birth.

If you have a high risk of getting a sexually transmitted infection, for example if you or your partner has more than one partner, it may be advisable not to use a diaphragm or cap. Research shows that spermicide which contains Nonoxinol 9 does not protect against sexually transmitted infections. It may even increase the risk of getting a sexually transmitted infection.