There has been a long debate about the significance of premature progesterone (P) rise during the late follicular phase, commonly known as premature luteinization (PL), and its implication on assisted reproductive technology (ART) outcomes.
PL is usually defined as an elevation of serum P ≥1.5ng/ml in the follicular phase before triggering administration for final oocyte maturation in controlled ovarian stimulation (COS) cycles.
PL is not uncommon and could not be completely prevented by the use of either gonadotropin-releasing hormone GnRH agonist or GnRH antagonist regimens.
PL could be detected in all profiles of patients undergoing COS such as hyper-responders, normal responders, and poor responders, and single in vitro fertilization (IVF) cycle can be exempted from it.
It has been reported that PL could affect about 12.3% to 46.7% of fresh IVF cycles4. This wide range of incidence of PL could be attributed to the heterogeneity of methods, cut-off points, and even definitions used to diagnose PL.
Also, various risk factors could affect the incidence such as a history of recurrent IVF failure, and patient characteristics including age, ethnicity, and body mass index. The COS protocol, daily follicle-stimulating hormone (FSH) dose, total dose of gonadotrophins, duration of the COS cycles, number of retrieved oocytes, and peak estradiol level ,were assumed to be contributory for increasing the chance of prematurely elevated (P) For example, ovarian stimulation using recombinant FSH alone without luteinizing hormone (LH) seems to be risky for higher PL incidence.