Analysis of the application value of chromosome microarray analysis technique in NT abnormal fetus HE Shu-feng，ZHAO-Li1，XIAO Jian-ping，ZHANG Jian-ping，SU Jing-Na （The Affiliated Wuxi Matermity and Child Health Care Hospital of Nanjing Medical University，Medical genetics and prenatal diagnostics. wuxi，Jiang su, 214000，China） Objective: To explore the value of chromosome karyotype and CMA in NT abnormal fetus. Methods: Analysis the following prenatal diagnosis results: Simple abnormal NT, abnormal NT and ultrasound, abnormal NT and advanced age, abnormal NT and bad reproductive history, abnormal NF and nuchal cystic hygroma. Results: Fetal aneuploidy(1.887% ) and CMA(13.208%) in the NT group. Fetal aneuploidy(42.857%) and CMA(28.57%)was found in nuchal cystic hygroma. Trisomy 21 (5.279%)and 45, X( 1.173%) had the highest proportion in fetal aneuploidy. Pathogenic and possibly pathogenic copy number variation accounted for 25% in 48 cases chromosome microdeletions/microduplications, and 22q11.21 fragment duplication was the most common. CMA detected 15.434% abnormal copy number in 311 normal karyotypes. Conclusion: At risk of invasive prenatal diagnosis, pregnant women should be informed of the advantages of CMA prenatal testing techniques, and chromosome microarray analysis should be recommended for NT abnormal fetuses.