Abstract: Objective Granulosa cell apoptosis has a direct impact on the quality of embryos,and the telomere was involved in the regulation of cell proliferation.The aim of this paper is to explore the relationship between telomere length in the cumulus cell and pregnancy outcome following in vitro fertilization-embryo transfer(IVF-ET),and provide ideas for the evaluation of embryos and oocytes. Methods A total of 87 patients undergoing IVF-ET in our hospital between June,2015 and December,2016 were enrolled in this study.The patients were divided into four groups according to their ages:20-25 years old(21 cases);26-30 years old(24 cases);31-35 years old(23 cases);over 35 years old(19 cases).According to the maturation of oocyte,the patients were divided into immature granulosa cell group(45 cases) and mature granulosa cells group(42 cases).On the basis of vaginal ultrasound examination of pregnant bursa after embryo transplantation,the patients were divided into pregnancy group(43 cases) and non-pregnancy group (44 cases).The age of patients,the maturation of oocyte,telomere length in cumulus cells were compared among different groups;the levels of anti-Mullerian hormone(AMH) in follicular fluid of oocytes with different maturation and the apoptosis of granulosa cells in different pregnancy outcome group were analyzed.All data processing and analysis were performed using SPSS 22.0 statistical software. Results There were obvious difference in the telomere length in cumulus cells and maturation of oocyte among the 20-25 years group,31-35 years group and over 35 years group;and telomere length in cumulus cells around mature oocytes shortened gradually with age,the telomere length was negatively correlated with the age of patients(P<0.05).The telomere length of granulosa cells in the non-pregnancy group was shorter than that in the pregnancy group,the difference was statistically significant(P<0.05).The levels of AMH in follicular fluid of immature oocytes were significantly higher than that in mature oocytes,and the difference was statistically significant(P=0.007).The difference in the apoptotic rate of ovarian granulosa cells was statistically significant between non-clinical pregnancy group and the clinical pregnancy group(P<0.05). Conclusion The length of telomere shortens with age of patients,more obviously in non-pregnancy patients.The telomere length of cumulus cells is closely related with oocyte maturation and pregnancy outcome,with an important clinical research value.