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What is Basal Body Temperature?
Basal body temperature (BBT) is the temperature of your body at rest.
Why Would You Measure Your BBT?
BBT charting is a useful tool for couples trying to conceive because of its ability to confirm ovulation. BBT charting also helps the couple understand more fully the physiological processes surrounding ovulation. Not all women ovulate 14 days before their next period. In fact, for many women, the time between ovulation and their period (called the luteal phase) is shorter. A woman needs to have at least 10 days in this phase in order to allow enough time for the fertilized egg to reach the uterus and implant. If it is less, she will need to resolve the short luteal phase if she desires to maintain a pregnancy.
Is BBT Charting Enough?
No. Charting temperatures will only tell you when ovulation has already occurred. Since an egg can only live about 12 to 24 hours, by the time your temperatures rise a day or two after ovulation, the egg will already be gone. So when charting your fertility signs in order to time intercourse, it is most useful to chart your cervical fluid to determine when you are in your most fertile phase.
How Do You Take Your BBT?
Your BBT is taken orally with a special BBT thermometer. This type of thermometer is graduated in easy-to-read one-tenth degree increments. Your temperature must be taken before any activity, first thing in the morning, after at least three hours of consecutive sleep. The thermometer must be shaken down the night before, because even this activity can raise your temperature -- and you are looking for as little as two-tenths of a degree of difference. Be sure to read the instructions that come with the thermometer. They are usually very complete.