Follicular progesterone elevations with ovulation induction for IVF.

The purpose of this review is to analyse the sources and effects of follicular progesterone elevations during ovarian stimulation, with the underlying mechanisms and preventive strategies on the in vitro fertilisation pregnancy outcome. In the early follicular phase, a flare-up effect of gonadotrophin releasing hormone (GnRH) agonists and incomplete luteolysis in GnRH antagonist regimens can result in significant elevations of progesterone. In the late follicular phase, progesterone elevations in GnRH analogue cycles are the result of the ovarian stimulation itself, driven by high follicle stimulating hormone dosage, estradiol levels, the number of follicles and oocytes. It seems that progesterone elevations (> or = 1.5 ng/mL or 4.77 nmol/L) have a detrimental effect on the outcome of pregnancy, accelerating the endometrial maturation. The most appropriate choice to avoid the negative effects of follicular progesterone elevations is to cancel fresh embryo transfer and to transfer frozen-thawed embryos in natural cycles. To prevent follicular phase elevations it might be preferable to use milder stimulation protocols, earlier trigger of ovulation in high responders and single-blastocyst transfer on day 5. The optimal GnRH analogue protocols during the entire stimulation period appear to be the long agonist as well as "long" and long GnRH antagonist regimens.