Efficacy and safety of long-acting GnRH agonists in in vitro fertilization and embryo transfer.

The introduction of gonadotrophin-releasing hormone (GnRH) agonists combined with gonadotrophins is considered to be one of the most significant events in the development of in vitro fertilization and embryo transfer (IVF-ET) programmes. This article reviews the use of GnRH agonists in IVF-ET programmes and the efficacy and safety of long-acting GnRH agonists. The use of agonists results in higher clinical pregnancy rates, more supernumerary embryos for cryopreservation and allows convenient programming of oocyte recovery. There are different types of agonist and ovarian stimulation protocol available for clinical use. Recent meta-analysis of the Cochrane database has demonstrated the superiority of the long protocols over the short and ultra-short protocols for GnRH agonist use in IVF and GIFT. The depot injection offers increased clinical and patient compliance and improves efficacy of pituitary downregulation. However, compared with short-acting agonists, the depot preparations are associated with a longer period of stimulation and higher doses of gonadotrophins. To date, there is no evidence of an increased risk of pregnancy wastages or teratogenicity in human pregnancies exposed to long-acting agonists.