BBT and ovulation share an inseparable bond: the temperature starts to decrease right before ovulation, and increases right after it, commencing the luteal phase. This process usually happens around the 14th day of the cycle.
The basal temperature of a woman's body is lower during the follicular (first) phase and higher during the luteal (second) phase. If there is no pregnancy, we can see a subsequent drop in temperature at the end of the cycle. The differences in temperatures are really small — that's why it's so crucial to take your measurements at exactly the same time.
However, if your alarm clock was to ever fail you, you'll be always welcome to use our BBT calculator for pregnancy.  Read more