The Basal Body Temperature Method is also called BBT or the Symptho-Thermal Method. It requires careful and accurate measurement of daily morning temperature and precise recording of these temperatures. There are hormonal physiologic basis for this method. Before ovulation, a woman’s temperature is low because the Estrogen level in the body is higher than Progesterone. During ovulation, Progesterone levels exceed Estrogen levels which cause a spike in temperature. This happens usually for 3 days. After the temperature spike, you return to your normal low temperature, and Ovulation already took place. This is not a very popular natural family planning method mainly because it is difficult for some to give the commitment and responsibility it requires. But this method, for those who are able to do it correctly, has a very high success rate.
Measure and Record
To use this method, you are required to take your temperature as soon as you wake up, and as soon as you wake up means before doing anything at all. You should not go out of bed, eat, drink, have sex or smoke before taking your temperature. For your record to be accurate, temperature should be taken at the same time everyday. Using an alarm clock is a smart idea. Also, using the same thermometer is a must. There are special types of thermometer especially made for BBT purposes available at your local pharmacy. These thermometers are more accurate in detecting even 0.1 F fluctuations in your core temperature. Lack of sleep affects your core temperature. It is ideal that you have at least 4-6 hours of sleep the night before you take your temperature. Where you document your temperature readings is up to you, but there are lots of BBT monitoring sheets downloadable from the internet.
Note That Fluctuation
During ovulation, your temperature increases about 1-2 F and is sustained for around 3 days. These are the days when you are likely to have your ovulation. If you are trying to get pregnant, it is best to have sex at least 2 days before and during this 3 day spike. If you are avoiding pregnancy, it is best to abstain completely from sex during these days. The reason why some couples use this method is because they have shorter abstinence period. With the correct implementation, BBT is a very effective and safe family planning method.