〔Abstract〕 Objective To compare the early embryonic developmental potential and clinical outcomes of oocytes matured in vivo and those matured by modified in vitro maturation(LVM) technology during the same controlled ovarian hyperstimulation(COH) cycle,and to explore the clinical application of melatonin-supplemented IVM technology.Methods 159 patients were recruited into the study.920 mature oocytes were collected during their COH cycles processed for conventional IVF/ICSI protocols,while 1 283 immature oocytes from the same cycles were matured in a melatonin-supplemented IVM medium before ICSI was performed.A retrospective analysis was conducted to compare the impact of conventional assisted reproductive technology and improved IVM technology on the outcomes of assisted reproductive therapy and pregnancy outcomes.Results Compared with mature oocytes collected from COH cycles treated with conventional IVF/ICSI,oocytes promoted by improved melatonin-supplemented IVM technology had a lower rate of high-quality blastocyst formation.However,after embryo transfer,there was no significant difference in the clinical outcomes of mature oocytes obtained through two methods,including clinical pregnancy rate,full-term birth rate,neonatal length,and neonatal Apgar score.Conclusion The application of melatonin-supplemented IVM significantly increases the utilization of immature oocytes collected from COH cycles,improving the pregnancy outcomes of patients assisted by assisted reproductive technology.