The prognostic importance of the number of oocytes retrieved and estradiol levels in poor and normal responders in in vitro fertilization (IVF) treatment

A low response to ovarian stimulation in in vitro fertilization poses a unique therapeutic challenge. Gonadotropin-releasing hormone agonists (GnRHa) have been suggested as a modality for treatment of this condition. In this study, we analyzed the results of 880 in vitro fertilization treatment cycles with respect to modality of ovarian stimulation, degree of hormonal response, and number of oocytes retrieved. In patients with estradiol (E₂)levels less than 501 pg/ml on the day of human chorionic gonadotropin administration, 27% pregnancy rate was achieved with clomiphene citrate (CC) combined with human menopausal gonadotropin (hMG), compared to 15.1% (P <0.005) with hMG alone and 20.8% (NS) with GnRHa and hMG. Pregnancy rates were not lower in these patients compared to patients with higher estradiol levels in the different stimulation protocols, but pregnancy rates were significantly lower in cycles during which three or fewer oocytes were retrieved, compared to those in which four or more oocytes were retrieved (10.8 vs 23.8%; P <0.0005). In low-retrieval cycles pregnancy rates actually decreased with increasing levels of estradiol. Our results indicate that the number of oocytes retrieved is a better prognostic parameter than E₂levels in predicting the outcome of in vitro fertilization treatment and that GnRHa in the long protocol do not seem to be superior to CC combined with hMG for the treatment of poor responders.