Cumulative exposure to high estradiol levels during the follicular phase of IVF cycles negatively affects implantation

Purpose: To investigate the effect of the cumulative exposure to estradiol (E₂) during the follicular phase on IVF outcome. Methods: Patients were stimulated with recombinant FSH after GnRH agonist suppression and had a day 3-embryo transfer. Estrogen exposure was determined as the area under the curve (AUC) for serum E₂ levels measured from the first day of stimulation through the day after hCG administration. Results: E₂ AUC thresholds for 10th and 90th percentiles were 4704 pg/ml and 16338 pg/ml, respectively. The pregnancy and implantation rates were highest in the 10th–90th percentile group, and were statistically higher in this group than in the >90th percentile group (54.6% vs. 33.3% and 24.8% and 12.9%, respectively, for pregnancy and implantation rates, P < 0.05). Recovered mature oocytes, fertilization, and number and mean score of transferred embryos were similar. Conclusions: High cumulative E₂ exposure during the follicular phase of IVF cycles has detrimental effects on implantation.