Human chorionic gonadotrophin and steroid concentrations in follicular fluid: the relationship to oocyte maturity and fertilization rates in stimulated and natural in-vitro fertilization cycles

The study investigates the relationship of follicular fluidsteroids and human chorionic gonadotrophin to oocyte maturityand fertilization rates in stimulated and natural cycles. Oestradiol,progesterone, testosterone and human chorionic gonadotrophinwere quantified in 129 samples of follicular fluid and the progesterone:oestradiol ratio calculated. Both stimulated cycles (short andlong luteinizing hormone-releasing hormone/human menopausalgonadotrophin regimens) and natural cycles were compared. Atotal of 60 women were studied, 20 in each group. In the naturalcycles, testosterone was significantly lower in follicles withintermediate oocytes (P = 0.015). Both oestradiol and testosteronewere significantly lower in stimulated cycles compared to naturalcycles (P = 0.032 and P = 0.034 respectively). In the ovarianstimulation cycles, the progesterone: oestradiol ratio was significantlyhigher when oocytes fertilized (P = 0.052). Moreover, in thestimulated cycles, oestradiol and human chorionic gonadotrophinwere significantly lower in the short protocol compared to thelong protocol. The data demonstrate that the hormonal milieuof the follicle is altered in downregulated stimulated cyclesto varying degrees, depending partially on the type of protocolused. Furthermore, the progesterone: oestradiol ratio, ratherthan individual hormone concentrations, may be a useful predictorof the fertilizing capacity of the oocytes.