An integrated view on the luteal phase: diagnosis and treatment in subfertility.

The term 'luteal phase deficiency' was first coined more than 60 years ago, and, since then, it has been suggested as a clinical entity per se and an aetiological factor for subfertility, implantation failure and recurrent miscarriage. Despite the existing recommendations for rational work-up in subfertility, luteal phase evaluation and progesterone therapy alone is still common in daily practice. This review comprises results from a Pubmed literature search with the terms 'luteal phase' and 'subfertility', focussing on clinical situations not primarily related to assisted reproduction techniques. Additional data from the experimental studies published in the past 10 years on follicular maturation, oocyte developmental competence and the ovulatory cascade are integrated into the clinical continuum of dysfunctional ovulation, menstrual cycle irregularity and impaired corpus luteum function. As reliable diagnostic tools for adequate luteal function are missing, the presence of clinical symptoms such as cycle irregularity or premenstrual spotting is indicative and should initiate early follicular phase diagnostic work-up. New evidence on the interdependence of oocyte and follicular maturation and resulting developmental competence of the embryo further support the use of ovarian stimulation as the first-line therapeutic option in different subsets of patients with subfertility including luteal phase deficiency.