The association of serum estradiol level with outcomes of clomiphene citrate/human menopausal gonadotropin ovarian stimulation for in vitro fertilization and embryo transfer

BACKGROUND: The purpose of this study was to test the hypothesis that estradiol (E(2)) level on day 3 may be associated with in vitro fertilization (IVF) outcomes. METHODS: The records of patients who received clomiphene citrate 100 mg/day plus human menopausal gonadotropin 150 IU/day from day 3 and received frozen-thawed embryo transfers were reviewed. Patients were divided into three groups: group A (E(2) ≤30 pg/ml), group B (30< E(2) ≤50 pg/ml), and group C (E(2) >50 pg/ml). A total of 1080 cycles from 941 patients were included. RESULTS: The number of eggs and MII oocytes were less in group C than group A (both, P = 0.001). The embryo implantation (P = 0.006) and clinical pregnancy rates (P = 0.036) were lower in group C than group B, and the rates were similar between group A and B. CONCLUSION: Maintaining the serum E(2) level from 30 to 50 pg/ml may result in a higher clinical pregnancy rate in IVF cycles.