The use of antagonist controlled ovarian stimulation protocols has allowed the use of GnRH agonist to be used for final oocyte maturation. The use of GnRH agonist as ovulation trigger has been shown to reduce the risks for ovarian hyperstimulation syndrome (OHSS), but its sole use results in reduced embryo implantation due to luteal phase insufficiency. The combination of GnRH agonist and variable doses of hCG for final oocyte maturation has been shown to overcome the luteal phase insufficiency effecting endometrial receptivity.