A diaphragm is a method of birth control. It’s a round, small dome of thin rubber stretched over a flexible ring. The diameter is normally anywhere between 60-100mm.
It’s inserted in the vagina before starting sex.
The girl has to insert it carefully and this asks for some practise.
If insert it well the reliability is 95%. But in practise 18 out of every 100 women who use it become pregnant after one year. So it’s not very safe. But it’s a great supplement if you don’t want to rely solely on the condom.

How does it work?
Pros & cons

What works better: a diaphragm or an IUD?