When using fertility awareness methods it is good to combine several techniques or methods to cross-check your fertility signals, especially when learning fertility awareness methods and trying to avoid pregnancy. It is also good to include a method that enables you to confirm the passage of fertility/ovulation for that cycle. The Sympto-Thermal Method which uses a basal body thermometer or a digital thermometer to record a woman's daily waking temperature. This method does not give any warning of approaching ovulation, this is very important to remember if you wish to avoid getting pregnant. It does however tell you when ovulation is all done, confirming the passage of ovulation. Once ovulation is done, then you will be non-fertile for the rest of the cycle (about 10 days or so)

This method relies on precise recording of your body's resting temperature. For this method to be accurate, temps must be taken first thing in the morning, and at the same time each morning. The temperature must be recorded before ANY activity occurs, activity will raise the body's temperature and cause a misleading temperature reading. What I do is set my alarm next to my bed within arm's reach, when it goes off in the morning, I roll over, turn it off, and put my digital thermometer in my mouth, take my temperature, when that is done, then I can get up to go to the bathroom, or get a drink of water, or go back to sleep.

There is a really great book that covers this method in great detail, written by Toni Weschler, I highly recommend anyone considering fertility awareness methods, even if you choose not to use the Sympto-Thermal method, to get this book. Its called Taking Charge of Your Fertility - The Definitive Guide to Natural Birth Control and Pregnancy Achievement. I wish I had this book when I was learning fertility awareness methods, even though I opted not to use a basal thermometer (using a plastic speculum instead) to confirm the passage of fertility each cycle, still it would have given me lots of valuable information during those learning years.

This method is fairly involved, the actual taking and recording the temperatures on a chart is actually pretty easy, but when temperatures don't show the "text book" fertility patterns, it can be difficult to interpret and confusing for women who are learning these methods, Ms Weschler goes into a lot of detail explaining how to interpert the BBT charts, I haven't had a lot of experience with this method, so I'll cover the basics to help get you started, but I strongly recommend getting Toni's book.

What is a basal thermometer? A basal thermometer is different from a regular fever thermometer which measures temperatures in degrees. A basal thermometer measures temperatures by 10th's of a degree. A digital thermometer will also work.

After ovulation occurs the hole left behind by the egg is transformed by luteinizing hormone (which also caused ovulation to occur) into what is called the corpus luteum, which means "little yellow body". Its function is to secrete progesterone, when the endometrium is stimulated by progesterone it begins to grow and thicken in preparation in case an egg is fertilized this cycle. As progesterone gets into the bloodstream it causes the body's resting temperature to increase noticeable. Pre-ovulatory temperatures are usually below 97.4 degrees. Once ovulation occurs temperatures will rise a day or two later, and will stay higher than pre-ovulatory temperatures until menstruation begins. Usual post-ovulatory temperatures are at or above 97.7 degrees.

In order for this method to help you avoid pregnancy: