Follicular fluid progesterone concentration is associated with fertilization outcome after IVF: a systematic review and meta-analysis

Follicular fluid is a key biochemical environment for oocyte development. The potential effect of follicular progesterone level on successful fertilization is a subject of debate, and so the aim of this study was to provide a summary of the currently available evidence on the association between follicular fluid progesterone level and fertilization outcome. To do so, a systematic review and a meta-analysis were performed, with the literature searches being conducted in three databases (PubMed, Embase and the Cochrane Library) to identify all relevant studies published up to 19 August 2017. Data were available from 13 studies (four intracytoplasmic sperm injection [ICSI] and nine conventional IVF) and 1009 individually aspirated follicular fluid samples were included in the analysis. The progesterone levels in follicular fluid were significantly higher in normal fertilization than in failed fertilization, both in conventional IVF (33% difference, P < 0.001) and ICSI (34% difference, P = 0.004). Although these data show that fertilized oocytes are derived from follicles with higher levels of progesterone, the results must be interpreted with caution, because of various progesterone measurement methods and different treatment protocols and it is too early to state that follicular fluid progesterone level could be considered as a marker for oocyte quality.