Symptoms
If fertilization of the egg does not occur, the corpus luteum dies and stops producing hormones. The drop in progesterone during this time can be a factor in premenstrual symptoms, such as depression and "bad moods" associated with PMS. The drop in hormones also causes the uterine lining to break down and be expelled by the body along with some blood, at which point the cycle begins again.

Last updated: 28-Aug-07