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What are the ESTHER Trials?

  • A programme of Phase 3 randomised, multinational clinical studies
  • Investigating the safety and efficacy of a personalised approach to assisted reproductive technology (ART) for recombinant follicle-stimulating hormone (rFSH) compared with follitropin alfa
  • Involving more than 1,326 patients in 11 countries worldwide
  • ESTHER-I: Pivotal, Phase 3, non-inferiority trial comparing efficacy and safety of REKOVELLE® vs follitropin alfa in patients undergoing their first cycle of ovarian stimulation.2
  • ESTHER-II: Phase 3 trial evaluating the immunogenicity of follitropin delta in patients receiving repeated cycles of ovarian stimulation (cycles 2 and 3) following initial stimulation with REKOVELLE® or follitropin alfa in ESTHER-I.3



  1. NCT01956110. Available at: (accessed July 2023).

  2. Nyboe Andersen A et al. Fertil Steril 2017; 107(2): 387–396.

  3. Bosch E et al. Reproductive BioMedicine Online 2019;38:195–205.

Job Code: UK-REK-2300015 - Date of preparation: July 2023


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