BBT Shift
Sample Chart - BBT and Mucus Chart showing BBT Shift
Sample Chart - BBT and Mucus Chart showing
no BBT Shift because ovulation did not occur
The preovulatory BBT temperatures are remain at an overall lower level than postovulatory BBT temperatures. When ovulation occurs, the shift in temperature to the higher postovulatory phase is obvious. When you have counted three consecutive normal high temperatures you have confirmation that ovulation has occurred. You cannot ovulate again until the next cycle, and are considered infertile until menstruation. Postovulatory temperatures remain high until menstruation.
The three high temperatures must be normal. Disturbances such as illness, temperatures taken late, not enough rest, or excessive alcohol consumption the evening before can give a false high temperature. It is important when counting the three high temperatures that any such disturbances are taken into consideration. If you doubt that the temperature shift is normal - WAIT - until the disturbance has passed before counting three high temperatures. In the meantime, continue with careful mucus observations. Usually a false high temperature due to a disturbance will stay high for only one or two days. The exception to this is flu or cold that lasts more than one or two days.
If you have doubts about the temperature shift, mucus will be your reliable guide until the disturbance has passed and the situation is clarified.
The BBT Shift of 3 normal high temperatures parallels your mucus pattern. Your mucus pattern develops into a Peak day. The BBT Shift typically occurs on Peak day or a day before or after Peak day when the mucus pattern is drying up.
If you are taking your temperature it is important to understand the relationship between temperature and mucus. The BBT Shift and cervical mucus pattern are two symptoms of the same hormonal event – ovulation occurring in the cycle. Cervical mucus appears in anticipation of ovulation. The BBT Shifts after ovulation has occurred. Of the two symptoms, mucus is the more reliable for interpreting your fertility because it anticipates ovulation. Temperature is most useful and reliable when used with a clear understanding of mucus patterns.