Significance of premature progesterone rise in IVF.

Purpose of review The current review will focus on the cause of premature progesterone and its impact on endometrial receptivity and endometrial gene expression. Recent findings Premature progesterone rise in stimulated IVF cycles seems to have a negative impact on the pregnancy rate. The current knowledge on the cause of a premature progesterone rise is still limited; however, it seems that overstimulating the ovaries during the end of the follicular phase will lead to a premature progesterone rise. The negative impact on the outcome is mainly due to reduced endometrial receptivity as can be seen in the altered endometrial gene expression. Summary Future studies should focus on how ovarian stimulation can be tailored according to individual requirements of the patients, aiming on preventing a possible progesterone rise during follicular phase of stimulated IVF cycles.