The safety of ovarian stimulation procedures or the procedure of assisted reproduction in general can be estimated by various parameters. Two of the most important are the health of children born after the procedure and the incidence of ovarian hyperstimulation syndrome (OHSS). The latter is important because it is the most severe, potentially life-threatening complication of any stimulation procedure. The use of gonadotrophin-releasing hormone (GnRH) antagonists in ovarian stimulation protocols has had no impact on the health of children born. This was proven in 227 children born after the use of cetrorelix and in 73 children born after the use of ganirelix. To analyse the incidence of OHSS and the impact of GnRH antagonists on clinical pregnancy rates compared with the long protocol, a meta-analysis was done. This showed a reduction of OHSS with the use of cetrorelix. Furthermore, when compared with the long protocol, clinical and ongoing pregnancy rates were not significantly reduced with the use of cetrorelix. Taken together, the use of GnRH antagonists are safe with regard to children’s health. The incidence of OHSS does not increase with ganirelix, and a reduction can be expected with cetrorelix.