(1)A spermicide used correctly with a condom, however, can have a failure rate as low as 3 percent. But they are more expensive and have a shorter shelf-life. Spermicide is essentially caustic. Therefore, it damages the ecosystem and delicate skin of the vagina. Because of this, condoms with spermicide actually increase a woman’s risk of getting a bladder infection and can damage local defense mechanisms.

(2)IUDs are more than 99 percent effective in preventing pregnancy, but rare failures can happen. However, no form of birth control is 100 percent effective. While rare, it's possible to become pregnant while using an IUD. Typical use failure rate: 0.8%.