Spermicides Used Alone
Spermicides, which come in many forms–foams, jellies, gels, and suppositories–work by forming a physical and chemical barrier to sperm. They should be inserted into the vagina within an hour before intercourse. If intercourse is repeated, more spermicide should be inserted. The active ingredient in most spermicides is the chemical nonoxynol-9. The failure rate for spermicides in preventing pregnancy when used alone is from 20% to 30%.
Spermicides are available without a prescription. People who experience burning or irritation with these products should not use them.
Periodic abstinence entails not having sexual intercourse during the woman’s fertile period. Sometimes this method is called natural family planning (NFP) or “rhythm.” Using periodic abstinence is dependent on the ability to identify the approximately 10 days in each menstrual cycle that a woman is fertile. Methods to help determine this include:
- The basal body temperature method is based on the knowledge that just before ovulation a woman’s basal body temperature drops several tenths of a degree and after ovulation it returns to normal. The method requires that the woman take her temperature each morning before she gets out of bed. There are now electronic thermometers with memories and electrical resistance meters that can more accurately pinpoint a woman’s fertile period.
- The cervical mucus method, also called the Billings method, depends on a woman recognizing the changes in cervical mucus that indicate ovulation is occurring or has occurred.
Periodic abstinence has a failure rate of 14% to 47%. It has none of the side effects of artificial methods of contraception.