Our research group identified a series of reproductive hormone abnormalities that are associated with luteal phase deficiency. Based on our studies, we describe the pathophysiology of luteal phase deficiency as follows. There is a supraphysiologic luteinizing hormone pulse frequency throughout the luteal phase, which is followed by a luteinizing hormone surge of decreased magnitude. After ovulation, the corpus luteum secretes lesser amounts of all hormones, including progesterone, estradiol, and inhibin. Luteinizing hormone as atrophic hormone of the corpus luteum is decreased in its biopotency in the mid to late luteal phases. These events lead to a premature luteolysis and a subtle decrease in luteal phase duration and subsequently menstrual cycle length.