involves hormones- The patch delivers hormones that stop an egg from being produced.
forms a barrier- Condoms keep semen with sperm from reaching the vagina.
involves use of spermicide- A diaphragm blocks sperm from the cervix, and spermicide slows movement of sperm.
protects against STIs- Condoms help keep partners' body fluids from coming into contact.
the most effective method- Abstinence, if total and continuous, is 100 percent effective against pregnancy and STIs.