Serum cetrorelix concentrations do not affect clinical pregnancy outcome in assisted reproduction

Objective: To analyze the potential association between serum cetrorelix levels and clinical pregnancy outcome in patients who had undergone assisted reproduction cycles with a GnRH antagonist cetrorelix acetate 3-mg injection. Design: Retrospective case-control study. Setting: University-affiliated private-assisted reproduction center. Patient(s): 130 IVF and intracytoplasmic sperm injection first cycles, treated with the same cetrorelix acetate protocol, in two matched groups according to whether the cycle resulted in clinical pregnancy (n = 56) or not (n = 74). Intervention(s): Cetrorelix acetate administration at 3 mg in a sandwich protocol. Main Outcome Measure(s): Serum cetrorelix concentrations on the day of hCG administration with regard to clinical pregnancy outcome, pre- versus post-hCG percent change in serum E₂ levels and implantation rates. Result(s): The cetrorelix serum concentrations were in the range of 0.29 to 5.12 ng/mL. The comparisons between groups with and without clinical pregnancy revealed comparable serum cetrorelix levels. There was no significant correlation between the serum cetrorelix concentrations and percent change in pre- versus post-hCG serum E₂ levels. Serum cetrorelix levels were comparable among patients with various implantation rates. Conclusion(s): Although a wide range of serum cetrorelix levels could be detected during a GnRH antagonist cycle, these levels were comparable in patients with and without clinical pregnancies.