Baby Making

Basal body temperature (BBT) is the temperature of your body taken at rest, usually before getting out of bed and before any activity begins. Even the shaking down of the thermometer must be done the night before, as even this activity can result in a raise in temperature. BBT is taken with a special BBT thermometer. It is usually a thermometer with easy-to-read increments of one-tenth of a degree, available at pharmacies.        

One reason to measure the BBT is to chart it and use the information as a tool to understand the physiological changes surrounding ovulation. It may assist couples trying to conceive due to its ability to confirm ovulation. However, as the egg lives for about 12 to 24 hours post ovulation, the temperature rise a day or two after that indicates that the egg is already gone. Charting fertility signs using a combination of BBT charting and the presence and texture of cervical mucus (CM) will be of most use to indicate the most fertile phase. 

The typical range of BBT is 97.0 to 97.5 degrees Fahrenheit, when the presence of estrogen hormones keeps the BBT low. Then the progesterone presence immediately following ovulation will typically raise temperatures by 0.4 to 0.6 degrees at least, until the next menstruation cycle begins. This increase in temperature is indicative of ovulation. 

BBT charting should begin during day one of your menstrual cycle. On this first day of your period, record your temperature on notebook or graph paper. Continue to chart throughout your cycle noting any reasons for variations in your temperature on a daily basis. Among alleviations in temperature may be the result of sleeping less than 3 hours, a fever, having had an alcoholic drink the previous night or intercourse. 

BBT information gives a clearer picture of your cycles and may provide useful information in helping you with your fertility goals, either to achieve or avoid pregnancy. Awareness of one's fertility is highly effective when used correctly. BBT charting used together with identification of the other two fertility signs, cervical mucus and cervical positions would make one more attuned to the body's fertile phases and make attempts at conception less of a trial and error. 

However, not all women ovulate 14 days before the next menstrual cycle begins. Each woman may also experience different fertile phases from month-to-month. For many women, the luteal phase (the time between ovulation and the next period) may be shorter. At least 10 days is needed in this phase for the fertilized egg to reach the uterus and implant. Maintaining a pregnancy may require resolving the short luteal phase for some women, if known. This is where BBT charting helps. 

BBT changes are also known to be used to detect pregnancy, usually as a very early indicator. An elevated BBT past the time that your menstrual period is due could mean pregnancy is achieved. However, each woman is different and BBT changes may not always be indicative of pregnancy.

Example of a modern Digital Basal Thermometer: