A contraceptive diaphragm or cap is a circular dome made of thin, soft silicons that’s inserted into the vagina before sex as a form of birth control. It covers the cervix so sperm can’t get into the uterus to fertilise the egg. For this reason they’re sometimes called a ‘barrier method’ of contraception. You need to use it together with a spermicide.1
Diaphragms and caps are similar: diaphragms are circular domes with a flexible rim; caps are the same but smaller.2 They are available in different sizes and when you first start using one, your doctor or nurse can advise you on the correct size to use for you.1 They do not contain hormones. 2
