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

The aim of this study is to evaluate the correlation between serum estradiol (E-2) levels during artificial autologous frozen embryo transfer (FET) cycles and ongoing pregnancy/live birth rates (OP/LB). 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. Average and peak E-2 levels from 110 autologous artificial FET cycles from 95 patients were analyzed. Average E-2 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 E-2 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 E-2 levels. This study suggests that elevated E-2 levels in artificial autologous FET cycles are associated with lower OP/LB rates. Estradiol levels should be monitored during artificial FET cycles.