Supraphysiological estradiol levels do not affect oocyte and embryo quality in oocyte donation cycles

Abstract

BACKGROUND: The study aim was to determine whether supraphysiological estradiol (E₂) levels reduce oocyte/embryo quality in oocyte donation cycles. METHODS: A retrospective analysis of 330 consecutive fresh oocyte donation cycles was performed in an assisted reproductive treatment programme between January 1996 and December 2000. Throughout the study period, oocyte donors and recipients followed a standard synchronization regimen that did not vary. A serum E₂ level (peak E₂) was obtained from all oocyte donors on the morning of HCG administration. Peak E₂ values were grouped by 33rd percentile (group I, 3000 pg/ml). All embryo transfers were performed on day 3 after oocyte recovery. RESULTS: Comparisons between groups revealed no significant differences in the quality of oocytes retrieved, and in fertilization rates. Higher peak E₂ levels were directly correlated with a greater number of oocytes retrieved, embryos available for transfer and cryopreservation, and higher average embryo quality scores (P < 0.005). Compared with group I, group III had significantly higher embryo implantation rates (P < 0.05). CONCLUSIONS: Sustained supraphysiological E₂ levels do not adversely affect the quality of developing oocytes and embryos. On the contrary, elevated E₂ levels are associated with a larger number of oocytes and embryos and high-grade embryos for transfer/cryopreservation and, consequently, improved implantation rates.