MEDICAL ANIMATION TRANSCRIPT: A woman's reproductive system includes the vagina, cervix, uterus, fallopian tubes, and ovaries. During vaginal sex between a man and a woman, semen passes out of the man's penis into the woman's vagina in a process called ejaculation. Semen contains tens of millions of sperm. From the vagina, sperm can pass through the cervix, uterus and fallopian tubes to fertilize an egg from the woman's body. Fertilization of the egg marks the beginning of human development. A birth control sponge is a temporary method for women to prevent pregnancy, also known as birth control or contraception. The sponge is made of soft foam. It has a dimple on one side and a short cotton loop attached. The sponge prevents pregnancy in two ways. First, the sponge covers the woman's cervix to prevent sperm in the man's semen from answering her uterus. Second, the sponge contains a substance called spermicide that kills sperm. Birth control sponges are widely available without a prescription. To use a sponge, wash your hands and remove it from its package. Wet the sponge completely with clean water. Squeeze the wet sponge a few times to activate the spermicide inside the sponge. Next, hold the sponge with the dimple side facing up, and fold the sponge upward. With the loop hanging down, insert the folded sponge into the vagina. Push the sponge as far into the vagina as it will go with one or two fingers. When the sponge is released, it will unfold and cover the cervix. Check with your fingers to make sure the cervix is completely covered by the sponge and the loop hangs down in the vagina. A woman can have sex right away, or up to 24 hours after inserting the sponge. Do not leave the sponge in place for more than 30 hours. To remove it, insert a finger into the vagina to find the sponge's loop. Poke a finger in the loop and pull down slowly and gently. After removing the sponge, throw it in the trash. A birth control sponge is about 90% effective at preventing pregnancy if a woman uses the sponge correctly every time she has sex. This means about 10 out of 100 women will become pregnant each year. Sponges are about 85% effective with typical use, which means about 15 out of 100 women will become pregnant if they don't always use a sponge or don't always use it correctly every time they have sex. Using the sponge does not protect either sexual partner from getting sexually transmitted diseases, including HIV.