〔Abstract〕 Objective To investigate the occurrence, treatment and pregnancy outcome of multiple pregnancy afterin vitrofertilization and embryo transfer treatment(IVF-ET), and to provide reference for health care of iatrogenic multiple pregnancy and the prevention&treatment of artificial assisted multiple pregnancy complications. Methods Selecting 4 321 cases of patients with multiple pregnancy through treatment of in IVF-ET pregnancy, retrieving the patient information management system, counting the occurrence of iatrogenic multiplets and pregnancy outcomes, analyzing and comparing the indicators including the processing of multiple pregnancy and pregnancy outcomes according to whether the fetus was reducted or not. SPSS19.0 software was used for data analysis. The test methods mainly includettest, chi-square test, etc. Results ① The subjects were divided into two groups according to the chorionic nature of pregnancy: single chorionic multiple foetuses and independent chorionic multiple foetuses. There was no statistically significant difference in age, BMI, infertility type, transplantation cycle and embryo source between the two groups(P>0.05), and there were statistically significant differences in infertility years and causes between the two groups(P<0.05). ② The subjects were divided into three groups according to whether the fetus was reducted or not: natural fetus reduction, surgical fetus reduction, and non reduction. The rate of late abortion or induced labor in the Non Reduction group was higher than that in the Reduction group(χ2=12.426,P=0.002); the rate of premature birth in the Non Reduction group was higher than that in the Reduction group(χ2=196.038,P<0.001); the rate of cesarean section birth in the Non Reduction group was higher than that in the Reduction group(χ2=45.181,P<0.001); and the neonatal weight in the Non Reduction group was lower than that in the Reduction group(F=3.251,P<0.001). ③ The subjects were divided into two groups according to the number of continuous pregnancies: single and twin. There were statistically significant differences in pregnancy complications, preterm delivery rate, cesarean section rate and newborn birth weight between the two groups(χ2=156.648,P<0.001;χ2=94.572,P<0.001;χ2=32.042,P<0.001;t=14.928,P<0.001). Conclusion Iatrogenic multiple pregnancy has a high rate of pregnancy loss and a large number of maternal and infant complications, so iatrogenic multiple pregnancy should be avoided as far as possible. For patients with multiple pregnancies, the accurate determination of chorionic sex in early pregnancy and selective embryo-reduction surgery to reduce the number of fetuses,can effectively reduce pregnancy complications and improve obstetric outcomes.