When Is GnRH Best for Triggering Oocyte Maturation?

The relatively new use of gonadotropin-releasing hormone (GnRH) trigger as an alternative to HCG in antagonist IVF cycles is best limited to situations where women are not seeking to become pregnant immediately.

Key Points:

- GnRH trigger as an alternative to HCG in antagonist IVF cycles is worth considering for women who do not intend to
become pregnant immediately, such as for those who are donating oocytes to recipients or who want to freeze their own eggs for later use.

- While use of GnRH is shown to reduce the risk of OHSS, it is also less likely to lead to a live birth.

Experts for the Cochrane Menstrual Disorders and Subfertility Group reviewing the science studying the use of GnRH protocols for triggering oocyte maturation found that while the treatment reduces the risk of ovarian hyperstimulation, it also lowers the chance of pregnancy in fresh autologous IVF/ICSI treatment cycles when compared with HCG.

The experts concluded that current scientific evidence suggests that GnRH use is associated with a lower live birth rate and a higher rate of miscarriage. For example, for a woman who would have a 31% chance of achieving a live birth through HCG, her chance of a live birth with a GnRH agonist would be between 12% and 24%. Hence, they suggested that GnRH agonist use as an oocyte maturation trigger could be useful for women who are donating oocytes to recipients or for those who wish to freeze their eggs for later use.

In analyzing the data, the reviewers looked at 17 different studies that involved women at varying risk for ovarian hyperstimulation syndrome. Of the studies included in the review, 13 assessed fresh autologous cycles and four focused on donor-recipient cycles.

The benefit for GnRH agonists was seen in the reduction of ovarian hyperstimulation syndrome. The studies reviewed suggested that a woman with a 5% risk of OHSS with the use of HCG would have between a 0% and 2% risk of OHSS with the use of a GnRH agonist.

The findings only applied to fresh autologous IVF/ICSI treatment cycles. When the reviewers considered donor-recipient cycles, they found no evidence suggesting a difference in the live birth rate or ongoing pregnancy rate in assessing the two treatment methods.