Coordination of early antral follicles by luteal estradiol administration provides a basis for alternative controlled ovarian hyperstimulation regimens.

OBJECTIVE To investigate whether luteal E(2) administration reduces size discrepancies of early antral follicles. DESIGN Prospective, crossover study. SETTING ART unit, Clamart, France. PATIENT(S) Sixty women and 120 cycles. INTERVENTION(S) On cycle day 3 (baseline day 3), all women underwent measurements of early antral follicles by ultrasound and serum FSH and ovarian hormones. From day 20 until the next cycle day 2, 30 of them received oral 17beta-E(2), whereas the remaining women served as controls. The day after E(2) discontinuation (E(2) day 3) or on subsequent cycle day 3 (control day 3), participants were reevaluated as on baseline day 3. MAIN OUTCOME MEASURE(S) Magnitude of follicular size discrepancies. RESULT(S) Follicular size discrepancies and follicular diameters were significantly attenuated on E(2) day 3 (3.7 +/- 0.5 mm) as compared with baseline day 3 (4.9 +/- 1.0 mm), but not in controls (5.0 +/- 0.8 vs. 4.9 +/- 0.8 mm). FSH (4.3 +/- 1.9 vs. 7.3 +/- 3.3 mIU/mL) and inhibin B (34 +/- 28 vs. 71 +/- 32 pg/mL) levels were consistently lower on E(2) day 3 than on baseline day 3 but remained unchanged in controls. CONCLUSION(S) Luteal E(2) administration reduces the size and improves the homogeneity of early antral follicles on day 3. This approach may be instrumental in synchronizing follicular development during controlled ovarian hyperstimulation.