The Impact of Serum Progesterone Levels on the Results of In Vitro Fertilization Treatments: A Literature Review.

The aim of this review is to analyze the relationship between preovulatory progesterone (P) rise and in vitro fertilization (IVF) pregnancy outcomes. It also investigates the sources and effects of rises in progesterone levels, including the underlying mechanisms and potential strategies in preventing its elevation during ovarian stimulation. Progesterone is produced in the early follicular phase in the adrenal gland, which shifts toward the ovaries prior to ovulation. Several factors contribute to the etiology of P level increase including the number of multiple follicles, the overdose of gonadotropins and poor ovarian response. Nowadays, the influence of the preovulatory P rise on IVF outcome remains controversial. Several authors have failed to demonstrate any negative impact, while others reported a detrimental effect associated with the rise of P. It seems that P rise (1.5 ng/ml or 4.77 nmol/l) may have deleterious effects on endometrial receptivity, namely, accelerating the endometrial maturation process that subsequently narrows the period for implantation and thus decreases pregnancy rates. Recent studies have proposed different cutoffs according to the ovarian response, which may be a little high in patients with high response in relation to those of normal response or low response. To prevent a P rise, it might be preferable to use milder stimulation protocols, earlier trigger of ovulation, cryopreservation of all embryos and transfer in the natural cycle.