Medical thermometers, devices used to measure body temperature, are of many types. One type of medical thermometer with a very specific use is known as a basal thermometer. This type of thermometer measures what is known as “basal body temperature”, which is essentially the lowest temperature that a healthy body attains when it is at rest. Typically, basal body temperature is measured immediately after a person wakes up, although at this time, body temperature has already started to rise. However, this still eliminates the effects that physical activity and consumption of food have on body temperature, and is therefore very reliable.
In most situations, there is no need to measure basal body temperature. A normal thermometer can be used to measure body temperature at any time when the need arises and the circumstances allow it. The most common situation in which the basal body temperature is of interest is when tracking ovulation. Among women who are trying to become pregnant or who are avoiding pregnancy, basal body temperature is of great importance. Ovulation typically causes an increase in basal body temperature by less than one degree Fahrenheit. Normal temperature readings cannot usually detect such changes reliably because of the natural fluctuations in body temperature through the day. In addition, normal thermometers are not always equipped to detect such minute changes in temperature. However, by recording the body temperature immediately upon waking, and by using a basal thermometer to do this, changes of even 0.1 degrees Fahrenheit can be detected. If this is done regularly, a woman can determine when ovulation begins, and then take the required action.
If you need to record your basal body temperature, you should first of all maintain a chart with daily readings. You should try to take your temperature at the same time everyday, and use the same method too – consistently use the thermometer orally, rectally, or vaginally, and insert it in the same location and to the same depth. Also remember that activity affects body temperature – keep the thermometer easily accessible by your bedside, so that you can use it as soon as you open your eyes. Digital basal thermometers are the best – these are highly accurate and can measure body temperature in a little over 30 seconds. Many of these thermometers also have a number of functions that are extremely helpful, such as memory storage, and warning tones that help you place the thermometer properly.