The contraceptive sponge is a type of birth control (contraceptive) that prevents sperm from entering the uterus. The contraceptive sponge is a soft, disk-shaped device made of polyurethane foam that is inserted into the vagina to cover the cervix. The contraceptive sponge contains spermicide, which blocks or kills sperm.Before sex, the contraceptive sponge is inserted deep into the vagina, where it is held in place by vaginal muscles. The contraceptive sponge has a strap to assist with removal.Only one contraceptive sponge - Today Sponge - has Food and Drug Administration (FDA) approval in the U.S.The contraceptive sponge can prevent pregnancy but doesn't offer protection from sexually transmitted infections (STIs).