Why would your bbt yoyo just before period is due?

The luteal phase is the phase of the menstrual cycle that occurs after ovulation and before the onset of menstruation. During the luteal phase, the corpus luteum, which is a small gland that forms on the ovary after ovulation, produces the hormone progesterone. Progesterone helps to thicken the lining of the uterus in preparation for implantation of a fertilized egg.

If implantation does not occur, the corpus luteum will regress and progesterone levels will drop. This drop in progesterone levels causes the lining of the uterus to break down and menstruation to begin.

The basal body temperature (BBT) is a medida of the lowest temperature that your body reaches at rest during sleep. The BBT can be used to track ovulation, as it typically rises by about 0.2-0.5 degrees Fahrenheit after ovulation.

Just before menstruation is due, the BBT may yo-yo or fluctuate. This is because the levels of progesterone and estrogen in the body are changing rapidly at this time. These hormonal changes can cause the BBT to rise and fall.

If you are trying to conceive, it is important to be aware of the different phases of the menstrual cycle and the changes in BBT that can occur during each phase. This information can help you to identify the best time to have intercourse and improve your chances of conception.