A diaphragm is a reusable silicone cup placed over the cervix with spermicide before sex, with a typical-use failure rate of 17%.
It is a barrier method: the cup blocks sperm physically, spermicide disables what gets past the rim. A provider prescribes the fit. The usage rules matter for it to work at all: insert before sex (it can go in ahead of time), leave it in at least 6 hours after, add spermicide for each additional act, and never wear it past the recommended window. Refits are needed after pregnancy, major weight change, or pelvic surgery. Compared with top-tier methods it is far less reliable (the implant fails 0.1%), but it offers what they cannot: no hormones, nothing daily, use only when needed, instant reversibility. The cervical cap works the same way at a 22% typical failure rate. Neither protects against STIs, so condoms remain the add-on for that job. A diaphragm fits someone who specifically wants hormone-free, sex-timed contraception and will use it correctly every time.
What to do
Common questions
What is a diaphragm for birth control?
A diaphragm is a shallow, reusable silicone cup you place inside your vagina before sex so it covers the cervix, blocking sperm from reaching the uterus. You always use it with spermicide, which is spread inside the cup and around the rim, because the physical block alone is not reliable enough. It is prescription-only in the sense that a healthcare provider fits it or prescribes the right size. With typical use, the CDC puts its failure rate at 17%: about 17 in 100 people relying on a diaphragm for a year get pregnant. The cervical cap, its smaller cousin, fails 22% typically. The appeal is real: hormone-free, no daily anything, used only around sex, and fully reversible the moment you stop. The workload is also real: you have to insert it correctly every time (it can go in ahead of time and must stay in place for at least 6 hours after sex), add more spermicide for repeated sex, keep it clean, and get refitted after pregnancy, significant weight change, or pelvic surgery. It does not protect against STIs. It suits people who want a hormone-free, on-demand method and accept that 17% failure rate as the price.