What is it?
A diaphragm is a circular dome made of thin, soft latex (rubber) or silicone, and is inserted into the vagina before sex. A cap is similar but smaller.
How do they work?
A diaphragm or cap is inserted into the vagina before sex, to cover the cervix so that sperm cannot get into the womb. You need to use spermicide with it (spermicides kill sperm). After sex, you take out the diaphragm or cap and wash it. They are reuseable.
Diaphragms and caps come in different sizes. You need to be fitted for the correct size by a trained doctor or nurse.
How effective is it?
If used correctly with spermicide, diaphragms and caps are 92-96% effective. This means that four to eight women out of every 100 who use a diahpragm or cap will become pregnant in a year.
There are no serious health risks, and you only have to think about it when you have sex. You can put them in several hours before you have sex.
Anything else to know about?
It can take time to learn how to use them. Some women suffer with cystitis when using them. Your doctor or nurse can check the size (switching to a smaller size may help).
If you lose or gain weight, or have a baby, miscarriage or abortion, you may need to be fitted for a new diaphragm or cap.
If you aren't in a monogamous (faithful) relationship you should help protect yourself against sexually transmitted infections by using condoms as well as a diaphragm or cap.