Measurement of basal body temperature
Basal body temperature („BBT“) is the temperature of a well-rested human body taken at rest in your mouth or vagina. Since BBT is one of the signs of fertility, its tracking is very important when practising the Symptothermal method. Thanks to consistency in noting down the BBT into a graph or a chart it is possible to determine whether ovulation has taken place and consequently also determine the end of the fertile days of the cycle.
When taking your BBT you need to comply with certain conditions such as:
- Take your temperature immediately after waking up, after at least six hours of sleep and before getting out of bed.
- For measuring your BBT always use the same thermometer.
- Take your temperature every day at the same time.
- Take your temperature in the same place (mouth or vagina) and for the same time period.
You can take your temperature in your mouth or vagina. It is important to keep in mind that the values measured in the vagina are about 0,3 - 0,6 degree higher and therefore it is suitable to always abide the place of measurement. The advantages of taking your basal body temperature in your vagina are more stable results, but it is not possible to take your temperature in the vagina during your menstruation – in this case you start with the measurement one day after the end of your period. The advantage of taking your BBT in your mouth is the continuity of measurements uninterrupted by menstruation.
The measurement accuracy can be affected by many factors such as illness, alcohol consumption, travelling, considerable temperature changes in the bedroom during the night, shorter night-time sleep, etc. You need to note down these facts into your BBT chart or graph and take them into account when evaluating the results.
Evaluation of the chart
During menstruation and in the time of ovulation you will measure out lower values. The day after ovulation your temperature will rise and this higher value will remain until the last day before menstruation when it will drop. Thus mostly the day of ovulation is the last day when women measure out lower values. In case a woman becomes pregnant, the temperature will not drop but will stay risen.
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