GnRH antagonists are safer than agonists: an update of a Cochrane review.

GnRH antagonists are safer than agonists: an update of a Cochrane review Background GnRH agonists or antagonists can be used to prevent LH surges during ovarian stimulation for assisted reproduction. GnRH agonists downregulate GnRH pituitary receptors. GnRH antagonists directly and rapidly inhibit gonadotrophin release. In a 2006 systematic review involving 29 trials, the average clinical pregnancy rate was 4.7% lower with GnRH antagonist treatment and the incidence of ovarian hyperstimulation syndrome (OHSS) was 2% lower compared with GnRH agonist treatment (Al-Inany et al., 2006). The current update includes 45 trials which addressed live birth or ongoing pregnancy rate (OPR) in GnRH antagonist and GnRH agonist protocols among women undergoing assisted reproduction treatment (Youssef et al., 2011).