The relationship between follicular fluid steroid concentration and successful fertilization of human oocytes in vitro.

Follicular fluids (FF) and their matched oocytes were obtained from 64 follicles of 28 women who failed to conceive after in vitro fertilization ( IVF ) and 33 follicles of 8 women who successfully conceived after the procedure. Ovulation was induced with human menopausal gonadotropin, and follicular aspiration was performed 36 hours after human chorionic gonadotropin administration. The concentration of 17 beta-estradiol, progesterone, testosterone, dihydrotestosterone, and androsterone was correlated with the morphology of the oocyte-corona-cumulus complex ( OCCC ), oocyte fertilization, the rate of cleavage, and the incidence of pregnancy after embryo transfer. In both groups of women, FF progesterone was lowest in follicles containing immature OCCCs . However, follicles aspirated from women who conceived after IVF which contained intermediate and mature OCCCs had significantly higher FF estradiol levels than similar follicles from women who failed to conceive after the procedure. Fertilized oocytes and 4- to 6-cell stage embryos which were obtained from follicles of pregnant women contained significantly higher FF estradiol levels than fertilized oocytes and similar embryos from nonpregnant women. It appears that higher FF estradiol levels correlate well with successful fertilization and an enhanced cleavage rate of oocytes associated with pregnancy following IVF .