Objective: To investigate the detection rates of chromosomal abnormalities and copy number variations in the fetuses of pregnant women with advanced maternal age in the second trimester

and to analyze the application value of chromosome microarray technique in the prenatal diagnosis of pregnant women with advanced maternal age. Methods: A retrospective analysis was performed for karyotype and chromosome microarray analysis（CMA）results of the pregnant women with advanced maternal age who underwent prenatal diagnosis in Quanzhou Maternal and Child Health Hospital from January 2018 to July 2020. Results: Karyotype analysis of amniotic fluid was performed for 1 338 pregnant women with advanced maternal age

among whom 3 had failed cell culture and 1 335 had a successful karyotype analysis

with a success rate of 99.76%. The results of karyotype analysis showed chromosomal abnormalities in 159 women

with a detection rate of chromosomal abnormalities of 11.91%（159/1 335）. The analysis of the detection rate of chromosomal abnormalities in pregnant women with advanced maternal age and other risk factors showed a significant difference in the detection rate of chromosomal abnormalities between groups（χ

2

=323.113

P

<

0.001）

and the highest detection rate of chromosomal abnormalities was observed in the pregnant women with advanced maternal age and high risk in noninvasive prenatal testing or two or more high-risk factors. Besides

CMA was performed for 207 pregnant women with advanced maternal age

and the results showed that compared with karyotype analysis

CMA identified 3 additional cases of pathogenic copy number variations

while compared with CMA

karyotype analysis detected 2 additional cases of chromosomal balanced translocation. Conclusion: There is a relatively high detection rate of chromosomal abnormalities in pregnant women with advanced maternal age

and there is a significant difference in the detection rate of chromosomal abnormalities between pregnant women with different high-risk factors. In addition

CMA can improve the detection rate of fetal chromosomal abnormalities in pregnant women with advanced maternal age and is thus recommended for fetal genetic analysis.