Objective:To investigate the effect of in vitro maturation(IVM)

fertilization and embryo transfer of immature oocytes derived from nature cycles in infertility couples.Methods:30 IVF/ICSI-ET cycles were involved in this study.Oocytes retrieval performed after follicle larger than 10 mm and before endogenesis Luteinizing hormone(LH) surge occurrence in nature cycle.Mature oocytes(Metaphase Ⅱ) were inseminated by standard in vitro fertilization(IVF) on the oocytes pick-up day.Immature oocytes(Metaphase I and germinal vesicle stage) were cultured for 24~48 hours and fertilized by intracytoplasmic sperm injection(ICSI) as soon as it developed to Metaphase Ⅱ stage.Embryo transfer was performed 72 h after fertilization.Results:2 of 30 IVM cycles brought no oocytes in this study.113 oocytes were obtained among other 28 oocyte retrieval cycles

74 of which were immature

29 were mature

and 10 were degenerated.60 of 74 immature oocytes developed to MⅡ after IVM(maturation rate 81.08%).6 cases of clinical pregnancy were obtained in the 20 embryo transfer cycles

five of which brought healthy babies(one came from immature oocyte and four came from mature oocyte) and one was abortive.Conclusion:IVM

fertilization and embryo transfer of immature oocytes derived from nature cycles is a feasible treatment for women with infertility.