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Fertility awareness-based methods (FAMs) are ways you can prevent pregnancy using your fertility pattern. Understanding your fertility pattern helps you predict ovulation — the day an egg is likely to be released. You can also use this information to help you become pregnant.

How FAMs Work
Women using FAMs for contraception do not have vaginal intercourse during their fertile or "unsafe days" — commonly called periodic abstinence. Or they use a barrier contraceptive during their "unsafe days." Determining your "unsafe days" is crucial.

Predicting Your "Unsafe Days"

Sperm can live up to to six days — possibly seven — in a woman's reproductive system, and an egg lives for about one day. In total, a woman has a good chance of becoming pregnant from unprotected vaginal intercourse over the course of about seven days of her menstrual cycle — as long as five days before the release of an egg (ovulation), the day of ovulation, and, possible, the day after ovulation.

Fertilization is most likely to take place from intercourse during the six days that end in ovulation.

There are various methods that help determine when the fertile phase may occur and when a woman should consider it unsafe to have unprotected vaginal intercourse:


For the basal body temperature method: Take your temperature every morning before getting out of bed. Your temperature rises between 0.4°F and 0.8°F on the day of ovulation. It remains at that level until your next period. Pregnancy may occur from vaginal intercourse during the six days before this rise in temperature.


For the cervical mucus method: Observe the changes in your cervical mucus. You must do so all through the first part of your menstrual cycle, until you are sure you have ovulated. Normally cloudy, tacky mucus will become clear and slippery in the few days before ovulation. It also will stretch between the fingers. When this happens you are most fertile. You must abstain from vaginal intercourse or use a barrier contraceptive during this time. This method is sometimes called the ovulation method.


For the calendar or "rhythm" method: Chart your menstrual cycles on a calendar. You may be able to predict ovulation if your periods are the same every month and if you chart many cycles before attempting to predict when you will ovulate. You must abstain or use a barrier method during your "unsafe days" before and after ovulation. It will be more difficult to predict the day of ovulation if your cycle length varies from month to month. In that case, you will have more "unsafe days." (It is best not to rely on this method alone.)


The symptothermal method: Since these above methods alone are so inaccurate, it is best to combine the basal body temperature method, the cervical mucus method, and the calendar method. Using the information from more than one of these methods can help you predict the fertile phase more accurately, and you will have fewer days of needing to abstain or use a barrier method.


For the Standard Days Method (SDM): Keep track of your menstrual cycle and do not have unprotected vaginal intercourse on days eight through 19. You may use the SDM only if you have regular menstrual cycles that are never shorter than 26 days and never longer than 32 days.

You may use a special string of beads — CycleBeads — to help you with the SDM. Each color-coded bead represents a day. Move the rubber ring onto one bead each day. The red bead represents the first day of your period. Brown beads represent days when you are very unlikely to get pregnant. White beads represent days when you are likely to get pregnant. Do not have unprotected vaginal intercourse these days.


For the post-ovulation method: Abstain or use a barrier method from the beginning of your period until the morning of the fourth day after your predicted ovulation — more than half of your menstrual cycle.

How Well FAMs Work
Of 100 women using FAMs about 25 will become pregnant during the first year of typical use. Perfect use can give better results. Nine women will become pregnant with perfect use of the calendar method. Five women will become pregnant with perfect use of the Standard Days Method. Perfect use of the post-ovulation method, the basal body temperature method, the cervical mucus (ovulation) method, or the symptothermal method results in only one to three pregnancies. Pregnancy rates generally are higher for single women who use these methods.

FAMs do not provide protection against sexually transmitted infections.