Elevated serum estradiol levels in artificial autologous frozen embryo transfer cycles negatively impact ongoing pregnancy and live birth rates

Purpose: The aim of this study is to evaluate the correlation between serum estradiol (E₂) levels during artificial autologous frozen embryo transfer (FET) cycles and ongoing pregnancy/live birth rates (OP/LB). Methods: A historical cohort study was conducted in an academic setting in order to correlate peak and average estradiol levels with ongoing pregnancy/live birth rates for all autologous artificial frozen embryo transfer cycles performed from 1/2011 to 12/2014. Results: Average and peak E₂ levels from 110 autologous artificial FET cycles from 95 patients were analyzed. Average E₂ levels were significantly lower in cycles resulting in OP/LB compared to those that did not (234.1 ± 16.6 pg/ml vs. 315 ± 24.8 pg/ml, respectively, p = 0.04). Although peak E₂ levels were not significantly different between cycles resulting in OP/LB compared with those that did not (366.9 ± 27.7 pg/ml vs. 459.1 ± 32.3 pg/ml, respectively, p = 0.19), correlation analysis revealed a statistically significant (p = 0.02) downward trend in OP/LB rates with increasing peak E₂ levels. Conclusions: This study suggests that elevated E₂ levels in artificial autologous FET cycles are associated with lower OP/LB rates. Estradiol levels should be monitored during artificial FET cycles.