Spermicidal pesaries, ointment and jelly, early 20th century.

Spermicidal pesaries are inserted into the vagina and work by destroying sperm before they can reach the uterus, thereby helping to prevent pregnancy. Spermicides are not very effective at preventing pregnancy when they are used on their own, but are useful for increasing the effectivenes of other contraceptive methods such as condoms, caps and diaphragms.