Abstract
A variety of protocols have evaluated the use of several forms of gonadotropins in controlled ovarian stimulation (COS). We aim to review the evolving trends on the use of gonadotropins human chorionic gonadotropin (hCG), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) over time and their combinations in COS for patients who undergo assisted reproductive techniques (ART) protocols. A meticulous search of three electronic databases was performed for articles published in the field up to September 2020. The administration of hCG seems a promising alternative to conventional modalities for COS related to the enhancement of LH activity. The use of gonadotropins was associated with significantly elevated pregnancy rates that ranged from 20.8% to 46.2%. However, the currently available outcomes with regards to oocytes retrieved, number of embryos are still conflicting. A potential beneficial effect was observed by the majority of the studies in terms of the number of embryos and implantation rates, which is, however, highly affected by the type of protocol used (gonadotropin-releasing hormone [GnRH] agonist or antagonist). Further studies are warranted to elucidate the exact pathways of action of gonadotropins in controlled ovarian stimulation to attain the optimal effect.