Luteal estradiol pre-treatment coordinates follicular growth during controlled ovarian hyperstimulation with GnRH antagonists

The purpose of this study was to investigate whether luteal estradiol (E(2)) administration reduces follicular size discrepancies and enhances ovarian response in recombinant FSH (r-FSH)/GnRH antagonist protocols.We studied prospectively 90 IVF-embryo transfer (ET) candidates who were randomly pre-treated with 17beta-E(2) (4 mg/day) from day 20 until next cycle day 2 (E(2) group, n = 47) or served as controls (control group, n = 43). On day 3, all women started r-FSH treatment. A single 3 mg dose of GnRH antagonist was administered eventually according to follicular maturation. Outcome measures were magnitude of size discrepancy of growing follicles on day 8 of r-FSH treatment and number of follicles >or=16 mm in diameter on the day of HCG.On day 8, follicles were smaller (9.9 +/- 2.5 versus 10.9 +/- 3.4 mm, P < 0.001) and their size discrepancies attenuated (P < 0.001) in the E(2) group compared with the control group. This was associated with more >or=16 mm follicles, mature oocytes and embryos in the E(2) group.Luteal E(2) administration reduces the pace of growth, improves size homogeneity of antral follicles on day 8 of r-FSH treatment and increases the number of follicles reaching maturation at once. Coordination of follicular development optimizes ovarian response to r-FSH/GnRH antagonist protocols and may constitute an attractive approach to improving their outcome.