GnRH Agonist and hCG (Dual Trigger) Versus hCG Trigger for Final Oocyte Maturation in Expected Normal Responders With a High Immature Oocyte Rate: Study Protocol for a Randomized, Superiority, Parallel Group, Controlled Trial.

Introduction: The choice of trigger drug for the controlled ovarian hyperstimulation (COH) protocol correlates with the outcome of Methods and Analysis: We propose a study at the Affiliated Hospital of Shandong University of Chinese Medicine. A total of 90 individuals undergoing COH use a fixed GnRH antagonist protocol. They will be assigned randomly into two groups according to the trigger method and timing: recombinant hCG (6500 IU) will be injected only 36 hours before OPU for final oocyte maturation (hCG-only trigger); co-administration of GnRH-a and hCG for final oocyte maturation, 40 and 34 hours prior to OPU, respectively (Dual trigger). The primary outcome is metaphase-II (MII) oocytes rate. Secondary outcomes are number of oocytes retrieved, fertilization rate, top-quality embryos rate, blastula formation rate, embryo implantation rate, clinical pregnancy rate, miscarriage rate, live birth rate, cumulative pregnancy/live birth rates, and ovarian hyperstimulation syndrome (OHSS) rate. Ethics and Dissemination: The reproductive ethics committee of the Affiliated Hospital of Shandong University of Traditional Chinese Medicine certified this study (Identifier: SDUTCM/2021.7.26) as ethical. All individuals will sign written informed consent. All data and biological samples will be protected according to law. The results of this study will be disseminated in a peer-reviewed scientific journal. Clinical Trial Registration: [chictr.gov.cn], identifier [ChiCTR2100049292].