Purpose: To determine the impact of elevated serum estradiol levels (EE2-defined as levels > 90th percentile) on the day of hCG administration during IVF on oocyte fertilization, embryo development, implantation, clinical pregnancy and miscarriage rates.
Methods: A total of 2,995 consecutive IVF cycles in 1,889 patients with non-donor oocyte retrieval resulting in fresh embryo transfer between 1/1/2005 and 12/31/2011 were analyzed. Cycles were stratified by serum E2 level on the day of hCG administration into those with levels >90th percentile and ≤ 90th percentile. Rates of normal fertilization, embryo development, positive pregnancy test, implantation, clinical pregnancy and spontaneous miscarriage were compared.
Results: Serum estradiol above the 90th percentile on the day of hCG administration was associated with a significantly lower rate of normal fertilization (68.6 ± 20 vs. 71.6 ± 21, p = 0.02) when compared with patients with a lower serum estradiol threshold. The proportion of embryos that progressed from 2PN to 6-8 cell on day 3 was not different between the two groups. Although rates of positive pregnancy test (55.2 % vs. 57 %), implantation (26.4 % vs. 28.5 %) and clinical pregnancy (45.5 % vs. 49.4 %) were lower in patients with a higher estradiol threshold, these differences were not statistically significant. Similarly, there was no difference in the spontaneous miscarriage rates between the two groups (8.4 % vs. 7.1 %).
Conclusions: Serum estradiol levels above the 90th percentile on the day of hCG administration is associated with lower oocyte fertilization rate; however, such levels do not impact embryo development, implantation, clinical pregnancy or spontaneous miscarriage rates.