Increasing uterine receptivity by decreasing estradiol levels during the preimplantation period in high responders with the use of a follicle-stimulating hormone step-down regimen.

OBJECTIVE: To analyze the effect on uterine receptivity of a decrease in E2 levels during the preimplantation period with the use of a step-down regimen in high responders undergoing IVF.
DESIGN: Prospective controlled clinical study.
SETTING: The Instituto Valenciano de Infertilidad. PATIENT(S): High responders in whom at least one previous IVF attempt failed in which 3-4 good-quality embryos were transferred and E2 levels were >3,000 pg/mL on the day of hCG administration. INTERVENTION(S): Gonadotropins were administered according to two different protocols. Blood samples were collected and IVF was performed. MAIN OUTCOME MEASURE(S): Serum E2 levels and reproductive outcome of IVF. RESULT(S): Estradiol levels on the day of hCG administration and throughout the preimplantation period and the number of oocytes collected were significantly lower with the use of the step-down regimen than during the previous failed cycle in which the standard protocol was used. The fertilization rate was similar and the number of good-quality embryos transferred was comparable. However, the implantation and pregnancy rates were significantly improved in patients who underwent the step-down regimen compared with those who received the standard protocol. CONCLUSION(S): With the use of a step-down regimen with FSH in high responders, our clinical results demonstrate that uterine receptivity can be improved when E2 levels are decreased during the preimplantation period.