Traditional serological screening uses pregnant women's serum markers such as AFP, ОІ-hCG, uE3, and inhibin-A to find high-risk pregnant women. At present, prenatal screening is an effective method to prevent birth defects. Chromosomal disease is one of the most common causes of birth defects. Among them, DownвЂ™s Syndrome (DS) cases increase about adds 23,000вЂ“25,000 every year. The annual birth defects rate in China is about 5.6%, with a growth of 900,000 cases each year. With the liberalization of birth policy, the number of births in China has gradually increased each year, and the rate of birth defects has also increased. It also has some certain reference value for SCA and CNV, but is not recommended for screening of other chromosomal aneuploidy. NIPT is indicated for trisomies 21, 18 and 13 screening, especially for T21. The overall PPV for other chromosome aneuploidy was 12.50%, with a FPR of 0.08%. Samples with high risk of other chromosomal aneuploidy were detected in 34 cases (0.13%), and the diagnosis was confirmed in 3 cases, which were T2, T9, and T16 respectively. Samples with high risk of CNV were detected in 104 cases (0.41%) and confirmed in 18 cases, with a PPV of 32.14% and a FPR of 0.15%. Samples with high risk of SCA were detected in 72 cases (0.28%), and the diagnosis was confirmed in 23 cases, with a PPV of 41.07% and a FPR of 0.13%.

Samples with high risk of autosomal aneuploidy were detected in 71 cases (0.28%), and 51 cases were confirmed, including: trisomy 21 (T21) in 44 cases, trisomy 18 (T18) in 5 cases, and trisomy 13 (T13) in 2 cases the positive predictive value (PPV) was 91.67%, 45.45%, and 33.33%, respectively, and the negative predictive value was 100%, the false positive rate (FPR) was 0.02%, 0.02%, and 0.02%, respectively.13 samples with high risk of mosaic trisomies 21, 18, and 13 were detected, and 1 case of T21mos was confirmed with a PPV of 8.33%. ResultsДЄ total of 25,517 pregnant women who received NIPT, 25,502 cases were tested successfully, and 294 high-risk samples (1.15%) were detected, there were 96 true positive samples, 117 false positive samples and 81 cases were refused further diagnosis. Materials and methodsДў5,517 pregnant women who underwent NIPT testing in Anhui Province Maternity and Child Health Hospital from September 2019 to September 2020 were selected, and samples with high-risk test results were subjected to karyotype analysis for comparison by using amniotic fluid, with some samples subjected to further validation by chromosomal microarray analysis, and followed up for pregnancy outcome. To assess the detection efficiency of noninvasive prenatal testing (NIPT) for fetal autosomal aneuploidy, sex chromosome aneuploidy (SCA), other chromosome aneuploidy, copy number variation (CNV), and to provide further data for clinical application of NIPT.

Sequential testing ppv