Final answer:
A diaphragm is a barrier method of contraception, placed over the cervix before intercourse to prevent sperm from entering the uterus, with a typical use failure rate of about 12 percent. It should be used with spermicide and does not protect against STIs.
Step-by-step explanation:
The plastic or rubber cover for the cervix that provides a contraceptive barrier to sperm is known as a diaphragm. A diaphragm is a barrier method type of contraception, which is placed over the cervix vaginally before sexual intercourse to prevent sperm from passing through to the uterus. Users are advised to apply spermicide to the diaphragm before insertion to enhance its effectiveness. Importantly, the diaphragm should remain in place for at least six hours following intercourse. Although it is a relatively effective form of birth control, with a typical use failure rate of about 12 percent, it does not offer protection against sexually transmitted infections (STIs) and may increase the risk of urinary tract infections.