Objective:To investigate the effect of gonadotropin (Gn) on embryo aneuploidy rate and pregnancy outcome during preimplanptation genetic testing for aneuploidy (PGT-A) cycles.Methods:The clinical data of patients undergoing PGT-A cycle at the First Medical Center of the PLA General Hospital from January 1, 2013 to May 31, 2019 were retrospectively analyzed. Patients were divided into younger patient group (<35 years old) and elder patient group (≥35 years old) by maternal age, then divided into two groups in line with Gn dosage (≤2 250 U, >2 250 U), and into four groups by number of oocytes retrieved (1-5, 6-10, 11-15 and ≥16 oocytes). The embryo aneuploidy rate and pregnancy outcome between the groups were compared. Logistic regression was used to analyze the relationship between the cumulative amount of Gn, embryo aneuploidy rate and live-birth rate.Results:A total of 402 cycles (338 patients) and 1 883 embryos were included in the study. (1) In the younger patients, the aneuploidy rate was 52.5% (304/579) in the group of Gn≤2 250 U and 48.6% (188/387) in the group of Gn >2 250 U, with no significant difference between them ( P=0.232). In the elderly patients, the difference in embryo aneuploidy rate between the two Gn group [57.9% (208/359) versus 60.6% (319/526)] was not statistically significant ( P=0.420). (2) The embryonic aneuploidy rate in different protocol of ovary stimulation was analyzed,in the younger group, the embryonic aneuploidy rate in patients using antagonist long protocol was 50.3% (158/314), it was 50.0% (121/242) in agonist long protocol, 52.1% (207/397) in agonist short protocol and 6/13 in luteal phase protocol, no statistical difference was found in above groups ( P=0.923); in the elder group, embryonic aneuploidy rate was 60.8% (191/314) in antagonist protocol, 58.4% (132/226) in agonist long protocol, 59.2%(199/336) in agonist short protocol, 5/9 in luteal phase protocol, respectively,no significant difference was found ( P=0.938). (3) In the younger patients, the aneuploidy rate in 1-5 oocytes group, 6-10 oocytes group, 11-15 oocytes group and ≥16 oocytes group was 37.9% (11/29), 54.0% (94/174), 52.5% (104/198) and 50.1% (283/565) respectively, no significant difference was found between the groups ( P=0.652); while in the elder patients, the difference between aneuploidy rate in each retrieved oocytes group [73.6% (89/121), 57.5% (119/207), 56.3% (108/192), 57.8% (211/365)] was statistically significant ( P=0.046). (4) Logistic regression analysis of age, cumulative dosage of Gn, number of oocytes obtained, and embryo aneuploidy rate showed that there was no association between the amount of Gn and embryo aneuploidy rate ( P>0.05); the increase in maternal age would increase the risk of aneuploidy rate of embryos, which was statistically significant ( OR=1.031, 95 %CI: 1.010-1.054, P=0.004); the increase in oocytes retrived would significantly decrease the risk of aneuploidy ( OR=0.981, 95 %CI: 0.971-0.991, P<0.01). (5) There was no significant difference in biochemical pregnancy rate [55.6% (80/144) versus 52.1% (63/121)], clinical pregnancy rate [50.0% (72/144) versus 47.9% (58/121)] and live-birth rate [46.5% (67/144) versus 40.5% (49/121)] between different Gn dosage groups ( P=0.613, P=0.738, P=0.324). The logistic regression analysis showed that the maternal age, the cumulative dosage of Gn, the number of oocytes obtained, and the ovarian stimulation protocol had no effect on the live-birth rate (all P>0.05). Conclusions:In PGT-A cycle, the dosage of Gn has no association with the embryo aneuploidy rate and pregnancy outcome. In the patients ≥35 years old, the increase in number of oocytes obtained may decrease the risk of aneuploidy. Age is an important factor affecting the embryo aneuploidy in PGT-A cycle.