Prenatal diagnosis and pregnancy outcome of 649 high-risk fetuses with noninvasive prenatal testing for sex chromosome abnormalities

Objective To analyze the prenatal diagnostic outcomes and pregnancy outcomes of 649 cases of fetuses with high-risk sex chromosomal abnormalities (SCA) indicated by non-invasive prenatal testing (NIPT), and to explore the screening value of NIPT for fetal SCA. Methods A total of 649 cases of pregnant women with high-risk SCA indicated by NIPT who underwent prenatal diagnosis in our hospital from February 2015 to February 2025 were selected. All cases underwent amniotic fluid cell karyotype analysis and chromosomal microarray analysis. All cases were followed up by reviewing medical records, accessing the Hangzhou Community Health Information System, and conducting telephone interviews, with the results recorded. Statistical analysis of the data was performed using SPSS 26.0 statistical software. Results Among the 649 pregnant women with NIPT-indicated high risk of SCA, 321 cases were true positive, with an overall positive predictive value (PPV) of 49.46%. The PPV of NIPT for high risk of 45,X, 47,XXY, 47,XXX, 47,XYY and X-chromosome copy number variation (CNV) were 25.30%, 95.05%, 62.22%, 63.93% and 68.12%, respectively. The PPV of the X-chromosome gain group was significantly higher than that of the X-chromosome loss group (78.39% vs 32.39%, χ²=111.6, P<0.001). The overall PPV of advanced-age pregnant women was slightly higher than that of young-age women, with no statistically significant difference (54.05% vs 47.63%, χ²=1.96, P ≈ 0.161 > 0.05). Among pregnancy outcomes, live birth rates for 47,XXX, 47,XXY, 45,X, 47,XYY, and X chromosome copy number variation (CNV) abnormalities were 80.36%,20.83%,48.19%,76.92%, and 63.83%, respectively. Conclusion NIPT has high clinical value in screening fetal sex chromosomal abnormalities, especially for screening sex chromosome aneuploidy gain and X-chromosome CNV abnormalities. The PPV of NIPT for SCA screening has no significant correlation with clinical detection indications, and advanced maternal age is not an independent risk factor for sex chromosomal abnormalities.