The symptoms and body-temperature method (also known as the symptothermal method) includes observing cervical mucus, recording basal body temperatures, noting menstrual symptoms and keeping track of your menstrual cycles to predict your fertile days. Combining all the information obtained from each source gives the best estimate of your fertile time.

To use this method, you will need to record your basal body temperature every morning when you wake, evaluate your cervical mucus daily, note any menstrual symptoms and make note of your typical menstrual cycle. Menstrual symptoms may include breast tenderness, changes in the position and firmness of the cervix, lower back pain, bloating and abdominal pain.

After your last day of menstrual bleeding, sexual intercourse is permitted every day until cervical mucus appears, or until the date that corresponds to 20 days subtracted from your shortest cycle length, whichever happens first. This is when your fertile time begins.

The end of your fertile time occurs three days after your cervical mucus disappears, or once three consecutive days of elevated temperature readings are noted and are not the result of a fever or other health issue. Remember, your temperature rises slightly when you have ovulated and remains elevated until your period begins.

Once your fertile time ends, you may resume sexual intercourse until your next menstrual cycle begins.

Charts are available that allow you to document all of these observances at the same time.

This method is more complex, although not dramatically better or more accurate, than the other methods. Perfect use of this method results in a 2-percent rate of pregnancy in the first year of use, not significantly better than the 3-percent pregnancy rate associated with the cervical-mucus method.

Advantages

• This method does not cost anything, and there is no need for medications or surgery.
• This method does not interrupt or alter fertility. Pregnancy is possible as soon as this method is abandoned.

Disadvantages

• When used imperfectly, this method has a pregnancy rate as high as 84 percent.
• Because of normal variations in the menstrual cycle and in the lifespan of eggs (one to three days) and sperm (two to seven days), you will need to abstain from intercourse for a number of days, including those immediately around ovulation, to be safe.