Chemical Barriers Chemical barriers prevent pregnancy by killing sperm before they ever reach the egg. Another name for them is spermicide . The intrauterine device , or IUD, is in a special classification all its own. Permanent Methods Permanent birth control methods prevent pregnancy by permanently blocking fertilization from occurring, blocking sperm from ever coming into contact with the egg. Both men and women may be sterilized.
Sterilization is a surgical procedure done in a doctor's office or clinic.
It's generally the method chosen by couples who have already completed their family or who have decide that they never want to have children. No intervention methods are methods which rely on knowledge of when a woman is most likely to get pregnant and either abstaining from sex or using one of the above methods during the time when she's most likely to become pregnant, or ejaculating outside the vagina during sex. There are no special products to take or put in or on for these methods to work. They do, however, require careful planning and a commitment from both a woman and her partner in order to prevent an unwanted pregnancy.