Ultimately progesterone levels may drop early and menses will arrive sooner than expected. For reasons not wholly understood, the corpus luteum sometimes does not persist as long as it should. Failure of the uterine lining to respond can occur even in the presence of adequate follicle development and a corpus luteum that persists for the appropriate length of time. In this condition, the uterine lining does not respond to normal levels of progesterone. Therefore, should an embryo arrive and try to implant, the lining will not be adequately prepared, and the implantation will likely fail.
Progesterone is responsible for the rise in basal body temperature during the luteal phase.
Women who monitor their basal body temperature will thus often note that luteal phase temperatures do not stay reliably elevated for twelve days. Additionally, women who monitor the time of ovulation often notice that their next cycle begins sooner than the normal 12-14 days after ovulation. Once a diagnosis of LPD is suspected, a serum progesterone test will often be performed at about seven days past ovulation. In the case of inadequate corpus luteum performance, progesterone support may indeed be the appropriate solution. However, inadequate follicle development may also be causing the low progesterone levels.