Optimal time in the menstrual cycle for serum progesterone measurement to diagnose luteal phase defects

Inadequate production of progesterone by the corpus luteum results in luteal phase deficiency, which is a frequent cause of recurrent spontaneous abortion. The diagnosis is made by assessment of endometrial biopsy specimens. Measurement of serum progesterone offers a less invasive alternative, but its utility as a diagnostic test is limited since there is no agreement on the level that will accurately differentiate between normal and luteal …