Gonadotropin-releasing hormone agonist versus HCG for oocyte triggering in antagonist assisted reproductive technology cycles

Oocyte maturation triggering is the final differentiation process of an immature female egg cell before fertilisation, either in normal or stimulated ovarian cycles in assisted reproductive techniques. It is like the final ripening of a seed or the attainment of full functional capacity by a cell. There are two hormones that can be used to trigger oocyte maturation. These are human chorionic gonadotropin (HCG), which is the standard treatment, and gonadotropin-releasing hormone agonist (GnRH agonist). The aim of this review was to evaluate the effectiveness of GnRH agonists for the final step of ovarian stimulation, to make the follicles (eggs) mature and ready for fertilisation, in in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI) cycles which used GnRH antagonist to suppress the pituitary gland. To obtain a reliable assessment of the effects of GnRH agonist on the outcomes we reviewed data from 11 randomised controlled studies involving 1055 women. The quality of the trials was good and there was evidence of a lower live birth rate, reduced ongoing pregnancy rate and higher miscarriage rate in women who received a GnRH agonist for final oocyte maturation trigger compared to women given HCG, in fresh autologous cycles (woman's own eggs). However, ovarian hyperstimulation, which is a complication from some forms of fertility medication, was significantly lower in the GnRH agonist group. We recommend that GnRH agonist as a final oocyte maturation trigger should be not used.