Made from silicone, the diaphragm is a barrier contraceptive. Shaped like a dome, the woman places it deep inside her vagina so it fits over the cervix. It's held in place by suction.
By covering the cervix, the diaphragm prevents any sperm from entering the womb and fertilising an egg. To aid its effectiveness, spermicide (a gel which kills sperm) is squirted on to the upper side of the diaphragm prior to insertion. You put it in before sex and leave it there for at least six hours after having sex (it comes with a strap or loop, which you pull to remove the cap).
Hormone free, so there are none of the physical side effects that come with some other contraceptives. It has no serious health risks.
Fiddly and not for the squeamish. Putting it in before you have sex can kill the moment and you must ensure you have it with you in case you decide to have sex. Forgetting to remove it can cause cystitis and, in rare cases, toxic shock syndrome. It can't be used during a period and it doesn't protect against sexually transmitted infections (STIs) so to have safe sex, you will still need to use condoms.
Anyone who feels confident enough to insert it properly although women who have had children may have weak vaginal muscles, which will make it difficult to hold in place. You can't use it if you're allergic to latex. Although you will be taught how to use it by a GP, nurse, you must use it correctly or it won't be effective. Consider your lifestyle. If you are forgetful or enjoy spontaneous sex and don't feel you would be able to interrupt proceedings to insert the cap, it's not for you.
Last updated July 31, 2018