Also the Cochrane review by Al-Inany reported that the incidence of severe OHSS is significantly lower in protocols with GnRH antagonists than in protocols with GnRH agonists (RR 0.61; 95% CI 0.42-0.89; P = 0.01); moreover, secondary methods to prevent OHSS (such as coasting or cycle cancellation) need to be used more frequently during the GnRH-agonist cycles (OR 0.44;95% CI 0.21-0.93;P 0.03) [17]. This evidence concerns the gene GNRH1 and ovarian hyperstimulation syndrome.