Thermal Shift

14. Question: How much will my bbt temperature increase? What is a normal bbt "thermal" shift?

Answer: As discussed in previous questions and articles, your basal temperature is your "base" temperature at a "resting" state - measured in the morning prior to any activity at all. The basal body temperature method of fertility awareness is based on the principle that your body starts to "heat up" around 48 hours after you ovulate. This "warming trend" is caused by the production of the hormone progesterone, which is secreted by the ovarian follicle after the egg is released into the fallopian tube. The follicle, at this juncture, undergoes a transformation and becomes the "corpus luteum" (one the egg is expelled), and during the luteal phase of the menstrual cycle the corpus luteum produces and emits progesterone.

Therefore, if you are bbt charting or practicing methods of fertility awareness, then you can expect to see a temperature increase two day or so following the moment ovulation takes place. A typical bbt thermal shift will likely be between 0.4 °F and a full degree (or even a bit more). The minimum basal temperature increase will be 0.2°F. You may, in fact, measure a slight dip in your basal temp right before you see the rise. Note that no two bbt charts will be identical.

By tracking warming trends on your fertility chart, you'll know when you ovulate each month and time intercourse to better the odds of conceiving a baby. Other advantages of bbt charting? You'll also be able to confirm that you are ovulating regularly each menstrual cycle and you'll be able to identify possible cycle irregularities. BBT charting, under certain circumstances, can alert women to issues relating to fertility problems, hormonal imbalances, and menstrual health factors. A doctor will be able to help you interpret your chart.

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