Abstract: Objective To investigate the distribution and abnormalities of non-invasive prenatal testing （NIPT） results in pregnant women, and explore the factors influencing the positive predictive value of NIPT high-risk prenatal diagnosis and karyotype analysis. Methods The 16 523 pregnant women who underwent NIPT at a hospital from January 2018 to December 2020 were selected as the research subjects, and karyotype analysis was performed on those with high risk of NIPT results. The results were analyzed by descriptive epidemiological analysis method. Results Among 16 523 pregnant women, 183 cases had high risk of NIPT, and the high risk rate was 1.11%. There were significant differences in the high risk rate of NIPT among pregnant women with different age, serological screening results, abnormal ultrasound soft markers （USM） and nuchal translucency （NT） （all P<0.01）. A total of 150 cases received amniocentesis chromosome karyotype analysis, the karyotype examination rate was 81.97%. The choice of prenatal diagnosis was related to fetal NT （P<0.05）. The positive predictive value of karyotype analysis was 68.67% （103/150）. Among them, the positive predictive values of 21-trisomy （T21）, 18-trisomy （T18）, 13-trisomy （T13）, sex chromosome aneuploidy （SCAs） and other chromosomal abnormalities were 90.57%, 68.75%, 54.55%, 71.43% and 14.29%, respectively. The results of chromosomal abnormalities, USM abnormalities and NT all affected the positive predictive value of karyotype analysis （P<0.05 or P<0.01）. Conclusion T21 and SCAs are the main risk factors of NIPT in pregnant women. Maternal age, serological screening results, USM and NT all affect the detection rate of NIPT. The accuracy of NIPT results was related to the types of chromosomal abnormalities, USM abnormalities and NT.

Key words: Non-invasive prenatal testing, Chromosome abnormality, Prenatal diagnosis, Karyotype analysis