Charting Your Basal Body Temperature
What is basal body temperature?
Your basal body temperature (BBT) is essentially your body’s core temperature. As most people know, our normal body temperature 97ºF. However, when we are ovulating, our body’s temperature rises to 98ºF or higher, and remains elevated for a number of days. And since it is during ovulation when chances of conception are highest, many women use this tracking method as a means of natural birth control.
What will I need?
In order to take your basal body temperature, you will need a special type of thermometer that is able to record slight changes in your temperature. These basal thermometers can be found in the family planning aisle of your pharmacy. You can find them in the form of traditional mercury thermometers as well as in digital form, which are faster and easier to read. You may also consider buying a thermometer that remembers your last reading, especially if you want to go back to sleep after taking your BBT.
How is basal body temperature charted?
In order for the BBT method to be successful, you will have to take it every morning, preferably at the same time. For the best results, it may help to create a chart with the days of the month on the horizontal line and the temperature of your body on the vertical line. That way you simply have to plot each day’s temperature reading on the chart so that at the end of your cycle you can draw a line to see during which days your temperature was consistently highest. This will tell you when you were ovulating. You will probably need to do this for a few months before you will have a clear idea of the timing of your ovulation.
How do I start?
Begin charting on the first day of your menstrual cycle (or the first day of your period). However, don’t record your temperature, but rather the details of your period (i.e. heaviness, duration). On day five begin recording your BBT, and continue doing so until the end of your cycle. It is a good idea to also record other, more general information on your charts, such as any changes in vaginal discharge, breast tenderness and your mood in general. This will give you a better understanding of your menstrual cycle.
What factors might affect my BBT?
In addition to ovulation, your basal body temperature may be affected by any one of the following factors: lack of sleep, sexual intercourse, fever, or alcohol. That is why is recommended you chart your BBT for a period of several months, so as to account for any possible variations.
How accurate is this method?
When performed properly, this method is actually very effective in promoting fertility awareness, and as such can be extremely useful for couples who are either trying to prevent or become pregnant.
Can a BBT test detect a pregnancy?
The answer is yes. If your BBT remains high after your period is supposed to start, this could be an early sign of pregnancy. However, a pregnancy will become most apparent about 10 to 12 days after the date when your period was supposed to begin, when the body is releasing hCG in preparation for pregnancy.
Can a BBT test detect a miscarriage?
Once a pregnancy has been confirmed, you may want to continue performing routine BBT tests, as they can detect abnormalities in your pregnancy, including a miscarriage. If you suddenly notice you have a low body temperature, this could be a sign of miscarriage. However, a miscarriage can be detected even you never knew you were pregnant by observing 18 or more high BBTs, followed by a heavy period. This is also referred to as a chemical pregnancy.