Abstract
In vitro fertilization (IVF) and embryo transfer and intracytoplasmic sperm injection (ICSI) have allowed millions of infertile couples to achieve pregnancy. As an essential part of IVF/ICSI enabling the retrieval of a high number of oocytes in one cycle, controlled ovarian stimulation (COS) treatment mainly composes of the standard long gonadotrophin-releasing hormone agonist (GnRH-a) protocol and the gonadotrophin-releasing hormone antagonist (GnRH-ant) protocol. However, the effectiveness of GnRH-ant protocol is still debated because of inconsistent conclusions and insufficient subgroup analyses. This systematic review and meta-analysis included a total of 52 studies, encompassing 5193 participants in the GnRH-ant group and 4757 in the GnRH-a group. The findings of this study revealed that the GnRH-ant protocol is comparable with the long GnRH-a protocol when considering live birth as the primary outcome, and it is a favourable protocol with evidence reducing the incidence of ovarian hyperstimulation syndrome in women undergoing IVF/ICSI, especially in women with polycystic ovary syndrome. Further research is needed to compare the subsequent cumulative live birth rate between the two protocols among the general and poor ovarian response patients since those patients have a lower clinical pregnancy rate, fewer oocytes retrieved or fewer high-grade embryos in the GnRH-ant protocol.