Female physiology LH surge ovulation These events occur if the egg is not fertilized. Lh levels fall during the luteal phase and the corpus luteum degenerates. Progesterone levels fall and the uterine lining is no longer maintained Blood Levels of Pituitary Hormones phase Ovarian Cycle progesterone estro ⊥L ood Levels of Ovarian Hormones proliferative story hase ase Uterine Cycle