A controlled trial of natural cycle versus microdose gonadotropin-releasing hormone analog flare cycles in poor responders undergoing in vitro fertilization

Objective: To determine the efficacy of natural-cycle IVF compared with controlled ovarian hyperstimulation in poor responders. Design: Randomized, controlled study. Setting: Private center for assisted reproduction. Patient(s): One hundred twenty-nine women who were poor responders in a previous IVF cycle. Intervention(s): Fifty-nine women underwent 114 attempts of natural-cycle IVF, and 70 women underwent 101 attempts of IVF with controlled ovarian hyperstimulation with microdose GnRH analog flare. Main Outcome Measure(s): Number of oocytes retrieved, pregnancy rate (PR) per cycle, PR per transfer, and implantation rate. Result(s): The poor responders treated with natural-cycle IVF and those treated with micro-GnRH analog flare showed similar PRs per cycle and per transfer. The women treated with natural-cycle IVF showed a statistically significant higher implantation rate (14.9%) compared with controls (5.5%). When subdivided into three groups according to age (less than or equal to35 years, greater than or equal to36-39 years, greater than or equal to40 years), younger patients had a better PR than the other two groups. Conclusion(s): In poor responders, natural-cycle IVF is at least as effective as controlled ovarian hyperstimulation, especially in younger patients, with a better implantation rate.