The long-acting gonadotropin-releasing hormone analogues impaired the implantation rate.

Objectives To determine the efficacy and innocuousness of long-acting versus short-acting GnRH analogues (GnRH-a) in long protocol for in IVF-ET. Design Prospective randomized study. Setting The IVF unit at an academic hospital. Patients One hundred couples admitted for their first IVF-ET attempt. Main Outcome Measures Serum concentrations of LH, E 2 , and P during the all cycles and duration of pituitary desensitization were assessed, as well as fertilization rate, embryo quality, and implantation and pregnancy rates. Results Significantly more days (10.8±1.8 versus 9.2±1.7days) of stimulation and more ampules of hMG (47±22 versus 33±16) were necessary to obtain similar numbers of embryos of quality with the long-acting GnRH-a. Implantation and delivery rates were significantly lower with the long-acting GnRH-a (32.8% versus 21.1%; 48.9% versus 29.1 %, respectively). Conclusions As the long-acting GnRH-a might interfere with the luteal phase and embryo development, short-acting GnRH-a should be preferred for ovarian hyperstimulation in IVF-ET.