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

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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 0.05). 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. Non-invasive prenatal testing Copy number variation Pregnancy outcomes Positive predictive value Prenatal diagnosis Karyotype analysis Chromosomal microarray analysis Introduction Sex Chromosomal Abnormalities (SCA) encompass numerical and structural abnormalities of sex chromosomes. Numerical abnormalities of sex chromosomes are mainly sex chromosome aneuploidies, the most common of which are 45,X (Turner syndrome), 47,XXY (Klinefelter syndrome), 47,XXX, 47,XYY and mosaic sex chromosome aneuploidies. The incidence of sex chromosome aneuploidies is approximately 1/400, nearly twice that of trisomy 21 [ 1 ] . Structural abnormalities of sex chromosomes are mostly manifested as deletion, duplication, inversion and translocation of chromosomal segments, and fetal pregnancy outcomes and clinical symptoms caused by different types of structural abnormalities vary accordingly. SCAs present diverse clinical phenotypes, which not only involve the structure and function of the reproductive system, but may also be accompanied by structural and functional abnormalities of other organs, intellectual developmental disorders, mental and neurological dysfunctions [ 2 – 3 ] . With the development of high-throughput sequencing technology, non-invasive prenatal testing (NIPT) based on cell-free fetal DNA in maternal peripheral blood has been widely applied in the prenatal screening of trisomy 21, trisomy 18 and trisomy 13. With a false positive rate of 50%, and the detection rate for trisomy 21 is > 95% [ 4 ] . In recent years, the screening scope of NIPT has shown an expanding trend. The positive predictive value (PPV) of NIPT for screening sex chromosome aneuploidies ranges from 35% to 56%, which is evaluated as moderate, among which the PPV for 47,XXY and 47,XYY is higher than that for 45,X and 47,XXX [ 5 ] . Given that NIPT screening for sex chromosome aneuploidies is associated with a relatively high false positive rate, along with issues such as the potential increase in invasive prenatal diagnosis, relatively mild phenotypic manifestations of the diseases, a relatively high rate of continued pregnancy, and the possible risk of sex selection [ 6 – 8 ] , there is no definitive conclusion on whether sex chromosome aneuploidies should be included in routine prenatal screening. For NIPT screening of structural sex chromosome abnormalities (e.g., X-chromosome deletion or duplication), most reports are case-based, and large-scale data analysis remains lacking. Based on prenatal diagnosis results, this study retrospectively analyzed the genetic diagnosis results and pregnancy outcomes of fetuses with NIPT-indicated high risk of sex chromosomal abnormalities, especially X-chromosome copy number variations (CNVs). We aimed to investigate the overall PPV of NIPT for fetal SCAs in our region, so as to provide evidence for clinical genetic counseling. 1. Subjects and Methods 1.1 Subjects A total of 649 pregnant women who voluntarily underwent non-invasive prenatal testing (NIPT, including standard NIPT and NIPT-Plus) at the Prenatal Diagnosis Center of Hangzhou Obstetrics and Gynecology Hospital for various clinical indications from February 2015 to February 2025, and subsequently received invasive prenatal diagnosis due to NIPT-indicated high risk of sex chromosomal abnormalities (SCA), were enrolled as research subjects (501 cases of standard NIPT and 148 cases of NIPT-Plus). The demographic characteristics of the subjects were as follows: age ranged from 19 to 43 years, with 185 cases of advanced maternal age; 632 cases were spontaneous pregnancies and 17 cases were assisted reproductive technology (ART) pregnancies, all of which were singleton pregnancies. All subjects underwent amniotic fluid cell karyotyping and single nucleotide polymorphism array (SNP array) testing after prenatal genetic counseling and signing informed consent forms. Ineligible subjects were excluded in accordance with the Technical Specification for Prenatal Screening and Diagnosis of Fetal Cell-free DNA in Maternal Peripheral Blood (2016) [ 9 ] . This study was approved by the Hangzhou Women’s Hospital Ethics Committee (No. 2019-084-01), and all pregnant women signed informed consent forms strictly in accordance with ethical requirements. 1.2 Methods 1.2.1 Standard NIPT Detection A total of 5 mL of peripheral venous blood was collected from pregnant women, and cell-free fetal DNA (cffDNA) was extracted from maternal plasma for library construction. High-throughput gene sequencing and data analysis were performed using the semiconductor sequencing technology on the Ion Proton platform (Thermo Fisher Scientific, USA) with the BioelectronSeq4000 sequencer to predict the fetal risk ratio of chromosomal abnormalities. The results were expressed as Z-score risk assessment (normal range: -3 to 3). A Z-score ≥ 3 or ≤ -3 indicated high risk, and a Z-score between − 3 and 3 indicated low risk. 1.2.2 NIPT-Plus Detection A total of 10 mL of maternal peripheral blood was collected into EDTA anticoagulant tubes, and plasma was obtained by centrifugation. Plasma cffDNA was isolated and extracted via magnetic bead separation method. After library construction and quantification, high-throughput sequencing was conducted using the NextSeq 550AR sequencer (Illumina, USA). Software-based sequence alignment and analysis were performed; the proportion of each chromosome was calculated by increasing sequencing depth and optimizing algorithms to achieve the detection of chromosomal aneuploidy and microdeletion/microduplication. The results were also evaluated by Z-score risk assessment. 1.2.3 Amniotic Fluid Cell Chromosomal Karyotyping Collected amniotic fluid samples were cultured with the flask culture method for 7–10 days. Amniotic fluid cells were harvested, processed for slide preparation and G-banding following routine procedures. A total of 30 metaphase chromosome karyotypes were manually analyzed for each sample. Chromosomal karyotype description and diagnosis were performed in accordance with the International System for Human Cytogenomic Nomenclature (ISCN, 2020). 1.2.4 Single Nucleotide Polymorphism (SNP) Array Analysis Genomic DNA was extracted and subjected to whole-genome amplification, labeling, hybridization and scanning using the Cytoscan 750K SNP array whole-genome chip (Affymetrix, USA) in strict accordance with the manufacturer’s operating manual. Scanning results were analyzed by GenomeStudio software (Affymetrix, USA). 1.3 Statistical Methods Data were processed using the SPSS 26.0 statistical software. Count data were presented as frequency and percentage. The chi-square (χ²) test was used for intergroup comparison, and a P value < 0.05 was considered statistically significant. 1.4 Follow-up of Pregnancy Outcomes All pregnant women were followed up by reviewing medical records, accessing the Hangzhou Community Health Information System and conducting telephone interviews. Follow-up contents included fetal prenatal ultrasound findings, method of pregnancy termination, birth defects, gestational age at delivery, fetal sex and postnatal growth and development status. Routine follow-up was completed within 3 months after pregnancy termination or delivery. 2.Results 2.1 Prenatal Diagnosis Results All 649 pregnant women with NIPT-indicated high risk of SCA underwent amniotic fluid karyotyping and SNP array testing, and 321 cases were confirmed with SCAs. Among them:328 cases were NIPT-indicated high risk of 45,X, of which 83 cases were confirmed as 45,X abnormality and 13 cases as other chromosomal abnormalities by prenatal diagnosis;252 cases were NIPT-indicated high risk of sex chromosome gain, of which 189 cases were confirmed as sex chromosome gain abnormality and 2 cases as other chromosomal abnormalities; among the 189 confirmed sex chromosome gain cases, 101 cases were NIPT-indicated high risk of 47,XXY (96 cases confirmed as 47,XXY), 90 cases were NIPT-indicated high risk of 47,XXX (56 cases confirmed as 47,XXX and 1 case as other chromosomal abnormalities), and 61 cases were NIPT-indicated high risk of 47,XYY (39 cases confirmed as 47,XYY and 1 case as other chromosomal abnormalities);69 cases were NIPT-indicated high risk of X-chromosome copy number variation (CNV), of which 47 cases were confirmed as X-chromosome CNV abnormality and 3 cases as other chromosomal abnormalities. 2.2 Positive Predictive Value (PPV) of NIPT Among the 649 pregnant women with NIPT-indicated high risk of SCA, 321 cases were true positive, with an overall PPV of 49.46%. The PPV of NIPT for high risk of sex chromosome aneuploidy loss and gain was 25.30% (83/328) and 75.79% (191/252), respectively. The PPV of the sex chromosome aneuploidy gain group was significantly higher than that of the sex chromosome aneuploidy loss group (75.79% vs 25.30%, χ²=116.6, P < 0.001). The PPV of the X-chromosome gain group was significantly higher than that of the X-chromosome loss group (78.39% [156/199] vs 28.02% [109/389], χ²=114.6, P < 0.001). Further subgroup analysis showed that the PPV of NIPT for high risk of 45,X, 47,XXY, 47,XXX, 47,XYY and X-chromosome CNV was 25.30%, 95.05%, 62.22%, 63.93% and 68.12%, respectively (see Table 1 ). Table 1 Efficacy evaluation of NIPT for screening fetal sex chromosomal abnormalities SCA type NIPT positive Prenatal diagnosis confirmed abnormal Confirmed normal Discordant abnormalities PPV(%) 45,X 328 83 232 13 25.30% 47,XXX 90 56 33 1 62.22% 47,XYY 61 39 21 1 63.93% 47,XXY 101 96 5 0 95.05% X chromosome CNV 69 47 19 3 68.12% Total 649 321 310 18 49.46% In addition, 18 cases with discordant results between prenatal diagnosis and NIPT were identified incidentally, including 2 cases of pathogenic variants (1 de novo variant verified by parental peripheral blood SNP array testing) and 16 cases of variants of uncertain clinical significance (VOUS). Further parental peripheral blood SNP array verification was performed for 7 cases, revealing 2 de novo variants and 5 maternally inherited variants (see Table 2 ). Table 2 Details of 18 cases with discordant results between NIPT and fetal SNP array detection number NIPT bear fruit SNP bear fruit Prenatal diagnosis conclusion pregnancy outcome No. NIPT result SNP array result Prenatal diagnosis conclusion Pregnancy outcome 1 Sex chromosome loss 2q37.2q37.3 deletion (1.9 Mb), de novo variant Variant of uncertain clinical significance (VOUS) A female infant was delivered with normal growth and development 2 Sex chromosome loss 15q11.2q13.1 duplication (5.3 Mb), de novo variant VOUS A female infant was delivered with normal growth and development 3 Sex chromosome loss 17p13.3dup780.5Kb VOUS A female infant was delivered with normal growth and development 4 Sex chromosome loss 16p11.2 deletion (761.4 Kb), maternally inherited VOUS A male infant was delivered with normal growth and development 5 Sex chromosome loss 9p24.1 duplication (646.0 Kb), double duplication VOUS A male infant was delivered with normal growth and development 6 Sex chromosome loss 8q21.3 deletion (486 Kb) VOUS A female infant was delivered with normal growth and development 7 Sex chromosome loss 1q21.1 duplication (2.644 Mb) and 1q21.2 duplication (1.282 Mb) VOUS Fetal death, multiple fetal anomalies (suspected fetal tuberous sclerosis), cardiac rhabdomyoma 8 Sex chromosome loss 16p13.11 duplication (307.7 Kb), maternally inherited VOUS A female infant was delivered with normal growth and development 9 Sex chromosome loss 7q21.11 duplication (314.4 Kb), maternally inherited VOUS A female infant was delivered with normal growth and development 10 Sex chromosome gain 5p15.2 duplication (949.5 Kb) VOUS A male infant was delivered with normal growth and development 11 chrX:dup:2M-12M 15q14 duplication (608.7 Kb) VOUS A male infant was delivered with normal growth and development 12 Sex chromosome loss 16p13.11 duplication (827.2 Kb) VOUS A female infant was delivered with normal growth and development 13 Sex chromosome loss 2q31.2 duplication (561.5 Kb) VOUS A female infant was delivered with normal growth and development 14 Sex chromosome loss 6q16.1 duplication (2.1 Mb), maternally inherited VOUS A female infant was delivered with normal growth and development 15 Sex chromosome loss 10q21.1 deletion (1.6 Mb) VOUS A female infant was delivered with normal growth and development 16 Sex chromosome gain 1q43 duplication (171.2 Kb) VOUS A male infant was delivered with normal growth and development 17 Sex chromosome gain 16p11.2 duplication (804 Kb) VOUS A male infant was delivered with normal growth and development 18 Xp22.33-p22.31del7Mb 17q12 duplication (1.9 Mb), maternally inherited pathogenic variation A male infant was delivered with normal growth and development 2.2.1 Stratification by maternal age Among the 649 pregnant women with NIPT-indicated high risk of SCA, the maternal age distribution showed 185 cases of advanced maternal age (AMA, defined as gestational age at delivery ≥ 35 years) and 464 cases of non-advanced maternal age (non-AMA). The number of non-AMA pregnancies with NIPT-indicated high risk of SCA was relatively higher than that of AMA pregnancies. Further prenatal diagnosis confirmed positive cases in 100 AMA cases and 219 non-AMA cases, with a PPV of 54.05% (100/185) and 47.20% (219/464), respectively. Chi-square test was performed to analyze the correlation between the AMA and non-AMA groups, and no statistically significant difference was observed between the two groups (χ²=1.998, P ≈ 0.157 > 0.05).Subgroup analysis by SCA subtype revealed the following PPVs in the AMA vs. non-AMA groups:45,X: 22.37% (17/76) vs. 26.19%(66/252);47,XXY:95.47%(45/47)vs.94.44%(51/54);X-chromosome gain: 79.52% (66/83) vs. 78.45% (91/116);X-chromosome loss: 27.59% (24/87) vs. 33.77% (102/302).No statistically significant differences were identified between the AMA and non-AMA groups in all the above subgroups. 2.2.2 Stratification by clinical indication for NIPT testing The clinical indications for NIPT testing in the 649 pregnant women with NIPT-indicated high risk of fetal SCA were ranked in descending order as follows: abnormal serological screening for Down syndrome, advanced maternal age, voluntary request for NIPT testing, and abnormal ultrasound soft markers, accounting for 43.61% (222/509), 27.70% (141/509), 18.27% (93/509) and 6.48% (33/509), respectively.The number of cases confirmed with abnormalities by further prenatal diagnosis in each group was 97, 74, 43 and 20, with corresponding PPVs of 43.69% (97/222), 52.48% (74/141), 46.24% (43/93) and 60.61% (20/33), respectively. No statistically significant differences were found among all the above groups (see Table 3 ). Table 3 Detection efficiency of NIPT for various SCA subtypes stratified by clinical indications Panel A NIPT indication Overall 45.X 47.XXY High-risk True positive PPV (%) High-risk True positive PPV (%) High-risk True positive PPV (%) Advanced maternal age (>35 years) 185 100 54.05% 76 17 22.37% 47 45 95.74% Abnormal serological screening results 247 112 45.34% 142 37 26.06% 27 25 92.59% Abnormal soft ultrasound markers 41 26 63.41% 23 10 43.48% 5 5 100.00% voluntary request 176 81 46.02% 87 19 21.84% 22 21 95.45% Total 649 319 49.15% 328 83 25.30% 101 96 95.05% Panel B (Continued) NIPT indication 47,XXX 47,XYY X-chromosome CNV High-risk True positive PPV (%) High-risk True positive PPV (%) High-risk True positive PPV (%) Advanced maternal age (>35 years) 33 20 60.61% 15 10 66.67% 14 8 57.14% Abnormal serological screening results 31 18 58.06% 14 8 42.86% 33 26 78.79% Abnormal soft ultrasound markers 3 3 100.00% 7 6 85.71% 3 2 66.67% voluntary request 23 15 65.22% 25 15 60.00% 19 11 57.89% Total 90 56 62.22% 61 39 63.93% 69 47 68.12% 2.2.3 Efficacy evaluation of NIPT in screening fetal X-chromosome copy number variations (CNVs) Among the 649 cases with NIPT-indicated high risk of SCA, 69 cases were identified with high risk of X-chromosome CNV abnormalities, of which 47 cases were confirmed as X-chromosome CNV abnormalities and an additional 3 cases as other chromosomal abnormalities by further prenatal diagnosis. Of the 69 NIPT-indicated high-risk cases for X-chromosome CNVs, 61 cases were high risk of X-chromosomal segment deletion, with 43 cases confirmed abnormal by prenatal diagnosis, yielding a PPV of 70.49% (43/61); 8 cases were high risk of X-chromosomal segment duplication, with 4 cases confirmed abnormal by prenatal diagnosis, with a PPV of 50.00% (4/8). Among the 43 cases confirmed with X-chromosomal deletion by prenatal diagnosis, the abnormalities included 27 cases of Xp22.31 segment deletion, 8 cases of Xp22.33 deletion (including 3 cases of mosaic Xp22.31 segment deletion), and 8 cases of other X-chromosomal segment deletions. The deletion fragment size of the Xp22.31 segment was concentrated at approximately 1.68 Mb, and that of the Xp22.33 segment ranged from 21.5 to 58.3 Mb. The remaining 8 cases of other X-chromosomal segment deletions involved the Xq26.1q28, Xq22.1q22.3, Xq23q28 and Xq26.2q28 regions, as well as three large-segment deletions in the long and short arms of the X chromosome. The 4 cases confirmed with X-chromosomal segment duplication included the Xq11.1q28, Xp22.33 and Xp22.31 regions, all of which were pathogenic variants. 2.4 Pregnancy outcomes All 649 pregnant women with NIPT-indicated high risk of SCA were successfully followed up with no lost to follow-up cases. Among the 321 true positive cases, 155 cases underwent induced labor, and 166 cases achieved live birth with normal neonatal growth and development. Among the 18 cases with discordant results between NIPT and prenatal diagnosis, 1 case underwent induced labor, 1 case suffered fetal death due to multiple fetal anomalies, and 16 cases had normal delivery; the neonates showed normal growth and development at the 6-month postnatal follow-up. Among the 310 false positive cases, 5 cases underwent induced labor, including 2 cases due to subsequent abnormal ultrasound findings, 1 case due to homozygous mutation of fetal deafness gene detected by amniocentesis, 1 case due to severe preeclampsia, and 1 case for personal reasons. One neonate was diagnosed with multiple anomalies after birth, including anal atresia, ventricular septal defect, atrial septal defect, micrognathia, high-arched palate and glossoptosis. The remaining 304 cases had normal delivery with normal growth and development. Among the 321 cases with confirmed SCAs, the live birth rates of 47,XXX, 47,XXY, 45,X, 47,XYY and X-chromosome CNV abnormalities were 80.36% (45/56), 20.83% (20/96), 48.19% (40/83), 76.92% (30/39) and 63.83% (30/47), respectively. These results indicated that pregnant women carrying fetuses with 47,XYY, 47,XXX and X-chromosome CNV abnormalities were more likely to choose to continue the pregnancy compared with those with 45,X and 47,XXY abnormalities. 3 Discussion As a high-throughput, non-invasive detection method with high sensitivity and specificity for trisomy 21 (T21), trisomy 18 (T18) and trisomy 13 (T13) [ 10 ] , non-invasive prenatal testing (NIPT) has become one of the most commonly used prenatal screening technologies at present. Besides common chromosomal aneuploidies, sex chromosomal abnormalities (SCAs) represent another major category of genetic factors leading to birth defects. The incidence of fetal sex chromosome aneuploidies in human embryos is higher than that of trisomy 21, among which 45,X has the highest incidence of 1%–1.5% [ 11 ] . As a first- or second-line screening strategy for common fetal trisomies, NIPT exhibits high sensitivity and specificity, and it is also capable of detecting SCAs (including rare abnormalities) [ 12 ] . This study retrospectively analyzed 649 cases with NIPT-indicated high risk of SCA in our center, where 47,XXY, 47,XXX, 47,XYY, 45,X and X-chromosome copy number variation (CNV) abnormalities were the major subtypes. The results showed an overall positive predictive value (PPV) of 49.46%, with 47,XXY presenting the highest PPV, which is consistent with the findings of previous studies [ 13 ] . 3.1 Proportion and clinical significance of different NIPT indications In terms of clinical indications for NIPT, abnormal serological screening and advanced maternal age (AMA) accounted for the highest proportions. A total of 247 cases with NIPT-indicated high risk of SCA were identified in pregnant women with abnormal maternal serological screening (including high risk, critical risk and abnormal biochemical indicators) as the primary indication, accounting for 38.06% (247/649), among which 114 cases were confirmed positive by further prenatal diagnosis with a PPV of 46.15% (114/247). A total of 185 cases with NIPT-indicated high risk of SCA were found in pregnant women with AMA as the primary indication, accounting for 28.51% (185/649), with 100 confirmed positive cases and a PPV of 54.05% (100/185). These results were consistent with numerous previous studies [ 14 – 16 ] , directly reflecting that these two populations are the core target groups for SCA screening by NIPT, which is mainly attributed to the matching between the design of prenatal screening system and the risk characteristics of the population. The high proportion of abnormal serological screening as an indication is primarily due to the relatively high false positive rate of serological screening; however, abnormal results prompt most pregnant women to choose NIPT for further examination, and this high conversion rate leads to a large volume of NIPT tests in this population. In addition, serological screening is widely used as an initial clinical screening method, resulting in a much larger base of pregnant women with abnormal screening results than other indications. Precisely because of the high proportion of maternal serological screening, NIPT, as a highly accurate screening method, can further improve the detection rate of SCAs in pregnant women with abnormal serological screening results. The high proportion of AMA as an indication is mainly due to the positioning of AMA pregnant women as a high-risk group for overall chromosomal abnormalities and their low acceptance of invasive prenatal diagnosis, leading to a higher density of NIPT screening in this population. Studies have shown that AMA exerts differential effects on different types of SCAs [ 17 ] : for instance, the incidence of 45,X and 47,XYY is unrelated to maternal age, while AMA significantly increases the fetal incidence of 47,XXX and 47,XYY [ 18 – 22 ] . Therefore, in clinical genetic counseling, personalized risk assessment should be provided based on different SCA subtypes, combined with maternal age and screening indications. In the data of this study, we also found 41 cases with abnormal ultrasound soft markers as the clinical indication among NIPT high-risk cases, and 26 fetuses were finally diagnosed with SCAs, with a PPV of 63.41%, which was superior to other indications. Further subtype analysis revealed that the PPV of the sex chromosome gain group in this indication reached as high as 93.33% (14/15). Thus, for NIPT-positive pregnant women with this indication, we recommend early acceptance of further prenatal diagnosis to avoid missed diagnosis. Accordingly, we conclude that pregnant women with abnormal serological screening and AMA are the main target groups for fetal SCA screening by NIPT, and abnormal ultrasound soft markers can serve as an important auxiliary method for fetal SCA screening. 3.2 Positive predictive value (PPV) In this study, among 649 cases with NIPT-indicated high risk of fetal SCA, prenatal diagnosis confirmed 321 true positive cases, with an overall PPV of 49.46% (321/649), which was basically consistent with the 40%–77% reported in the literature [ 23 – 25 ] . The PPV of NIPT varied across different SCA subtypes: previous studies reported a PPV of approximately 47.8%–55.56% for 47,XXX, 17.50%–32.43% for 45,X, 56.52%–60% for 47,XXY, and 50%–87.50% for 47,XYY [ 26 – 28 ] . In this study, the PPV of 47,XXY was as high as 95.05%, and the PPVs for 47,XXX, 47,XYY and X-chromosome CNV abnormalities were 62.22%, 63.93% and 68.12%, respectively. In contrast, the PPV of 45,X was only 25.30%, indicating that NIPT performs better in predicting sex chromosome trisomies than X monosomy. This may be attributed to the following reasons [ 29 – 32 ] : the X chromosome harbors 1098 genes and the Y chromosome 78 genes, among which 58 are homologous genes on both sex chromosomes, and most of these genes (29 genes) are located at the terminal regions of sex chromosomes; the low guanine-cytosine (GC) content of the X chromosome leads to highly variable amplification of the X chromosome; non-random X-chromosome inactivation in placental tissues may account for the low PPV of Turner syndrome (45,X), with the paternal X chromosome tending to be inactivated in XX female trophoblast cells. In addition, age-related X-chromosome loss has been reported in leukocytes of normal women, which may affect the accuracy of fetal 45,X prediction by NIPT [ 33 ] . Furthermore, in this study, the PPV of NIPT for high risk of sex chromosome loss and gain was 25.30% (83/328) and 75.79% (191/252), respectively (χ²=145.7, P<0.001), indicating that NIPT has a better predictive value for sex chromosome gain than loss. The PPV of NIPT for high risk of X-chromosome loss and gain was 32.39% (126/389) and 78.39% (156/199), respectively (χ²=111.6, P<0.001), demonstrating a superior predictive value for X-chromosome gain over loss. In view of the high PPV of NIPT for screening sex chromosome gain and X-chromosome CNV abnormalities, as well as the high false positive rate for 45,X, we recommend that NIPT reports provide specific SCA subtypes to facilitate appropriate clinical counseling and recommendations based on different subtypes. Additionally, although the overall PPV of the AMA group was slightly higher than that of the non-AMA group (54.05% vs 47.63%, χ²=1.96, P ≈ 0.161 > 0.05), no statistically significant difference was observed. There were no significant differences in the PPV of each SCA subtype between the AMA and non-AMA groups, suggesting that maternal age is not a major influencing factor for NIPT prediction of SCAs, which is consistent with previous research [ 33 ] . No significant differences in the PPV of NIPT for SCAs were found among populations with different clinical indications, and further analysis of the PPV for each SCA subtype also revealed no notable disparities. Therefore, the PPV of NIPT for SCA screening has no significant correlation with clinical detection indications. 3.3 X-chromosome copy number variation (CNV) abnormalities This study specifically analyzed data of NIPT-indicated high risk of X-chromosome CNV abnormalities and found a PPV of 67.92% (36/53), second only to 47,XYY, with most cases being X-chromosome microdeletion abnormalities (PPV = 69.39%, 34/49). Analysis of 36 true positive cases with X-chromosome CNV abnormalities showed that the abnormalities mainly involved deletions in the Xp22.31 and Xp22.33 regions, all of which were pathogenic variants with variable deletion fragment sizes. Phenotypic abnormal syndromes associated with Xp22.3 depend on the range and nature of deleted or duplicated genes. The loci of Xp22.3 microdeletions/microduplications were almost identical, a phenomenon known as recurrent copy number variations. In this study, the deletion fragment size of the Xp22.31 region was concentrated at approximately 1.68 Mb, which is consistent with previous research [ 34 ] reporting that "approximately 70% of Xp22.3 microdeletions are recurrent Xp22.3 microdeletions with a fragment size of about 1.6 Mb, mainly involving the STS gene and flanking segments". Xp22.3 microdeletion in male fetuses is associated with X-linked ichthyosis (XLI, OMIM 308100). We also found that the PPV of X-chromosome CNV abnormalities was as high as 76% (19/25) in the population with abnormal serological screening as the NIPT indication, and 75% (6/8) in cases with abnormal serological multiple of the median (MoM) values. This suggests that X-chromosome CNV abnormalities may be associated with serological indicators, which is consistent with the finding by Langlois et al. [ 35 ] that maternal serum unconjugated estriol (uE3) MoM value < 0.25 is correlated with Xp22.3 microdeletion. This may be because fetal Xp22.3 microdeletion may cause loss of the STS gene, which impairs sulfatase activity in the placenta and further leads to decreased uE3 concentration in amniotic fluid [ 36 ] . In conclusion, NIPT has a relatively high PPV for fetal X-chromosome CNV abnormalities, especially in the population with abnormal serological screening, which can provide a reference for clinical genetic counseling. 3.4 Pregnancy outcome choices for fetuses with SCA abnormalities Follow-up of pregnancy outcomes for fetuses with SCAs showed that after excluding lost-to-follow-up cases, the live birth rates of 47,XXX, 47,XYY, X-chromosome CNV, 45,X and 47,XXY abnormalities were 80.00%, 73.33%, 63.89%, 36.20% and 23.29%, respectively. We found that pregnant women carrying fetuses with 47,XXX or 47,XYY were more likely to choose to continue the pregnancy. Multiple factors influence pregnancy decision-making, including conception method, adverse pregnancy and childbirth history, parental age, educational level, religious belief, social culture, economic status, fertility, number of existing children, expectation, parental perception of the anticipated disease, and even emotional stability during decision-making [ 37 ] , among which the severity of clinical phenotype is the most critical. 47,XXX and 47,XYY are associated with relatively mild phenotypes, while 45,X and 47,XXY often present with severe clinical phenotypes such as abnormal sexual development, reduced fertility and abnormal secondary sexual characteristic development, which are less acceptable to parents. The severity of clinical phenotypes of X-chromosome CNV abnormalities depends on the size and pathogenicity of the deleted/duplicated fragments. In this study, most X-chromosome CNV abnormalities were Xp22.31 region deletions with small fragment sizes and mild clinical phenotypes, resulting in a relatively high live birth rate. Therefore, NIPT reports are recommended to specify the SCA subtype, and provide fragment size if X-chromosome CNV abnormalities are involved, to assist pregnancy decision-making for pregnant women. 3.5 Incidentally detected CNV abnormalities In this study, 18 cases of autosomal CNV abnormalities were incidentally detected by prenatal diagnosis among NIPT-indicated SCA high-risk cases. Among the pregnancy outcomes, 1 case had fetal death due to multiple fetal anomalies, 1 case underwent induced labor, and the remaining cases achieved live birth with no obvious neonatal abnormalities. Of these 18 SCA high-risk cases, 13 were NIPT-indicated for sex chromosome loss, further indicating a high false positive rate of NIPT for sex chromosome loss. However, clinicians should not abandon further prenatal diagnosis for this group due to the high false positive rate. 3.6 Conclusion In summary, NIPT has high clinical value in screening fetal sex chromosomal abnormalities, especially for sex chromosome 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 fetal sex chromosomal abnormalities. In this retrospective analysis of the detection efficacy of NIPT for fetal SCAs, we included X-chromosome CNV abnormalities in the analysis, which fills the domestic and international data gap of NIPT in this field. However, this study is a single-center research with a relatively small sample size, and the findings need to be verified by multicenter, large-sample studies. Declarations Ethics approval and consent to participate This study involving human participants was conducted in accordance with the ethical standards of the Medical Ethics Committee of Hangzhou Women’s Hospital Ethics Committee (No. 2019-084-01) and the 1964 Helsinki Declaration. As this was a retrospective study,writteninformed consent was obtained from patients at the time of clinical care, and all data were analyzed anonymously. Consent for publication Not applicable. Funding ARTICLE IN PRESS Medical and Health Research Project of Meizhou City (No.2024-B-27). Author Contribution Qiuhong Huang:Project development, Data Collection, Manuscript writing. FengdanLai: Data analysis, Liubing Lan: Data Collection,Qiuhong Huang:Manuscript editing. Acknowledgements Not applicable. Data Availability The datasets used during the present study are available from the correspondingauthor upon reasonable request. References Boyd PA, Loane M, Garne E, Boyd PA, Loane M, Garne E, et al. 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Expert Rev Mol Diagn. 2019;19(6):537–42. Johnston M, Warton C, Pertile MD, Johnston M, Warton C, Pertile MD et al. Ethical issues associated with prenatal screening using non–invasive prenatal testing for sex chromosome aneuploidy[J].Prenat Diagn, 2023, 43(2): 226–34. Bowman–Smart H, Savulescu J, Gyngell C, et al. Sex selection and non–invasive prenatal testing: a review of current practices, evidence, and ethical issues[J]. Prenat Diagn. 2020;40(4):398–407. National Health and Family Planning Commission of the People's Republic of China. Technical specifications for noninvasive prenatal screening and diagnosis using cell-free fetal DNA. 2016-10–27. Juvet LK, Ormstad SS. Stoinska༧Schneider A,etal.NIPH systematic reviews:executive summaries.Non-invasive prenatal test(NIPT) for identification of trisomy 21,18 and 13[M].Oslo,Norway: Knowledge Centre for the Health Services at The Norwegian Institute of Public Health(NIPH) Copyrightź2016 by The Norwegian Institute of PublicHealth(NIPH).2016. Lu Guohui. Prenatal Diagnosis of Genetic Diseases [M]. Guangzhou: Guangdong Science and Technology; 2002. ChenYB. YuQ,MaoXY,etal.Non-invasive prenatal testing for chromosome aneuploidies and subchromosomal microdeletions/microduplications in a cohort of 42910 single pregnancies with different clinical features[J]. Hum Genomics. 2019;13(1):60. Shear MA, Swanson K, Garg R, Shear MA, Swanson K, Garg R, et al. A systematic review and meta-analysis of cell-free DNA testing for detection of fetal sex chromosome aneuploidy[J]. Prenat Diagn. 2023;43(2):133–43. Guan Xinlei H, Ruijie Z, Xueying, et al. Karyotype analysis of fetal chromosomes in 1104 pregnant women with different prenatal diagnostic indications [J]. Chin J Med Genet. 2024;41(1):5–21. Wang Yousheng Z, Cuicui C, Chanhui, et al. Correlation analysis between advanced maternal age and fetal chromosomal abnormalities [J]. Chin J Med Genet. 2021;38(1):96–103. Guo Fenglian Z, Rui L. The value of non-invasive prenatal genetic testing in screening for fetal chromosomal aneuploidies [J]. Chin J Practical Med. 2024;51(9):73–6. He Lin M, Duan D, Tao. Clinical Genetics [M]. Shanghai: Shanghai Scientific and Technical; 2013. pp. 61–88. CAROTHERS A D, COLLYER S, DE MEY R, CAROTHERS A D, COLLYER S, DE MEY R, et al. Parental age and birth order in the aetiology of some sex chromosome aneuploidies. Ann Hum Genet. 1978;41(3):277–87. FERGUSON-SMITH M A, YATES JR. Maternal age specific rates for chromosome aberrations and factors influencing them: report of a collaborative european study on 52965 amniocenteses[J]. Prenat Diagn, 1984, 4 Spec No: 5–44. SCHREINEMACHERS D M, CROSS P K, HOOK EB. Rates of trisomies 21, 18, 13 and other chromosome abnormalities in about 20000 prenatal studies compared with estimated rates in live births. Hum Genet. 1982;61(4):318–24. Elmerdahl Frederiksen L, Ølgaard SM, Roos L, Petersen OB, Rode L, Hartwig T, Ekelund CK, Danish Central Cytogenetics Registry Study Group, Vogel I. Maternal age and the risk of fetal aneuploidy: A nationwide cohort study of more than 500 000 singleton pregnancies in Denmark from 2008 to 2017. Acta Obstet Gynecol Scand. 2024;103(2):351–9. Lei Y, Dong M. [Association of maternal age with fetal sex chromosome aneuploidies]. Zhejiang Da Xue Xue Bao Yi Xue Ban. 2019;48(4):409–13. Li Y, Yang X, Zhang Y, Lou H, Wu M, Liu F, Chang W, Zhao X, Li Y, Yang X, Zhang Y, Lou H, Wu M, Liu F, Chang W, Zhao X. The detection efficacy of noninvasive prenatal genetic testing (NIPT) for sex chromosome abnormalities and copy number variation and its differentiation in pregnant women of different ages. Heliyon. 2024;10(e24155):1–10. Zhao Xiaoxi W, Aining Y, Rongcai, et al. Analysis of chromosomal abnormalities in pregnant women at high risk of non-invasive prenatal gene testing in Inner Mongolia Autonomous Region [J]. Chin J Obstet Gynecol (Electronic Edition). 2018;14(2):224–9. Hu H, Wang L, Wu J, Hu H, Wang L, Wu J, et al. Noninvasive prenatal testing for chromosome aneuploidies and subchromosomal microdeletions/microduplications in a cohort of 8,141 single pregnancies[J]. Hum Genomics. 2019;13(1):14. Wang C, Tang J, Tong K, Wang C, Tang J, Tong K, et al. Expanding the application of non-invasive prenatal testing in the detection of foetal chromosomal copy number variations[J]. BMC Med Genomics. 2021;14(1):292. Tang Lingfang L, Anping L. The application value of non-invasive prenatal testing technology in screening for fetal sex chromosome aneuploidy in singleton pregnancy [J]. J Guangxi Med Univ. 2020;37(11):2059–62. Tang LF, Liang AP, Li Y, Tang LF,Liang AP, Li Y et al. Application value of noninvasive prenatal testing in screening for sex chromosome aneuploidy abnormalities in singleton pregnancies[J]. J Guangxi Med Univ 2020,37(11):2059–62. Zhang B, Lu BY, Yu B, Zhang B, Lu BY, Yu B, et al. Noninvasive prenatal screening for fetal common sex chromosome aneuploidies from maternal blood. J Int Med Res. 2017;45(2):621–30. Zhu Y, Lu S, Bian X, Wang H, Zhu B, Wang H, Xu Z, Xu L, Yan W, Zeng Y, Chen Z, Tang S, Shen G, Miao Z. A multicenter study of fetal chromosomal abnormalities in Chinese women of advanced maternal age. Taiwan J Obstet Gynecol. 2016;55(3):379–84. Mavridi A, Ntali G, Theodora M, Stamatelopoulos K, Michala L. A spontaneous pregnancy in a patient with turner syndrome with 45, X/47, XXX Mosaicism: a case report and review of the literature. J Pediatr Adolesc Gynecol. 2018;31(6):651–4. Xu Y, Chen L, Liu Y, Hao Y, Xu Z, Deng L, Xie J. Screening, prenatal diagnosis, and prenatal decision for sex chromosome aneuploidy. Exp Rev Mol Diagnost. 2019;19(6):537–42. Lu X, Wang C, Sun Y, Tang J, Tong K, Zhu J, Wang C, Sun Y, Tang J, Tong K, Zhu J. Noninvasive prenatal testing for assessing foetal sex chromosome aneuploidy: a retrospective study of 45,773 cases. Mol Cytogenet. 2021;14(1):1–8. Jimenez Vaca AL, Valdes-Flores Mdel R, Rivera-Vega MR, Jimenez Vaca AL, Valdes-Flores Mdel R, Rivera-Vega MR, et al. Deletion pattern of the STS gene in X-linked ichthyosis in a Mexican population[J]. Mol Med. 2001;7(12):845–9. Langlois S, Armstrong L, Gall K, et al. Steroid sulfatase deficiency and contiguous gene deletion syndrome amongst pregnant patients with low serum unconjugated estriols [J]. Prenat Diagn. 2009;29(10):966–74. Zeng Y, Jianjun Z. Research progress of Xp22.3 microdeletion/microduplication [J]. Chin J Med Genet. 2020;37(5):584–7. Liang Chengchu W, Yousheng L, Jian Y, Jiexia W, Xingwang C, Hanbiao Y, Aihua. Prenatal diagnostic indications, pregnancy outcomes and influencing factors in 1 372 pregnant women with fetal sex chromosome aneuploidy [J]. Chin J Perinat Med. 2022;25(12):942–7. Additional Declarations No competing interests reported. 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Numerical abnormalities of sex chromosomes are mainly sex chromosome aneuploidies, the most common of which are 45,X (Turner syndrome), 47,XXY (Klinefelter syndrome), 47,XXX, 47,XYY and mosaic sex chromosome aneuploidies. The incidence of sex chromosome aneuploidies is approximately 1/400, nearly twice that of trisomy 21\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. Structural abnormalities of sex chromosomes are mostly manifested as deletion, duplication, inversion and translocation of chromosomal segments, and fetal pregnancy outcomes and clinical symptoms caused by different types of structural abnormalities vary accordingly. SCAs present diverse clinical phenotypes, which not only involve the structure and function of the reproductive system, but may also be accompanied by structural and functional abnormalities of other organs, intellectual developmental disorders, mental and neurological dysfunctions \u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eWith the development of high-throughput sequencing technology, non-invasive prenatal testing (NIPT) based on cell-free fetal DNA in maternal peripheral blood has been widely applied in the prenatal screening of trisomy 21, trisomy 18 and trisomy 13. With a false positive rate of \u0026lt;\u0026thinsp;0.5%, its positive predictive value is \u0026gt;\u0026thinsp;50%, and the detection rate for trisomy 21 is \u0026gt;\u0026thinsp;95% \u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn recent years, the screening scope of NIPT has shown an expanding trend. The positive predictive value (PPV) of NIPT for screening sex chromosome aneuploidies ranges from 35% to 56%, which is evaluated as moderate, among which the PPV for 47,XXY and 47,XYY is higher than that for 45,X and 47,XXX\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. Given that NIPT screening for sex chromosome aneuploidies is associated with a relatively high false positive rate, along with issues such as the potential increase in invasive prenatal diagnosis, relatively mild phenotypic manifestations of the diseases, a relatively high rate of continued pregnancy, and the possible risk of sex selection\u003csup\u003e[\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e, there is no definitive conclusion on whether sex chromosome aneuploidies should be included in routine prenatal screening. For NIPT screening of structural sex chromosome abnormalities (e.g., X-chromosome deletion or duplication), most reports are case-based, and large-scale data analysis remains lacking.\u003c/p\u003e \u003cp\u003eBased on prenatal diagnosis results, this study retrospectively analyzed the genetic diagnosis results and pregnancy outcomes of fetuses with NIPT-indicated high risk of sex chromosomal abnormalities, especially X-chromosome copy number variations (CNVs). We aimed to investigate the overall PPV of NIPT for fetal SCAs in our region, so as to provide evidence for clinical genetic counseling.\u003c/p\u003e"},{"header":"1. Subjects and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e1.1 Subjects\u003c/h2\u003e \u003cp\u003eA total of 649 pregnant women who voluntarily underwent non-invasive prenatal testing (NIPT, including standard NIPT and NIPT-Plus) at the Prenatal Diagnosis Center of Hangzhou Obstetrics and Gynecology Hospital for various clinical indications from February 2015 to February 2025, and subsequently received invasive prenatal diagnosis due to NIPT-indicated high risk of sex chromosomal abnormalities (SCA), were enrolled as research subjects (501 cases of standard NIPT and 148 cases of NIPT-Plus). The demographic characteristics of the subjects were as follows: age ranged from 19 to 43 years, with 185 cases of advanced maternal age; 632 cases were spontaneous pregnancies and 17 cases were assisted reproductive technology (ART) pregnancies, all of which were singleton pregnancies. All subjects underwent amniotic fluid cell karyotyping and single nucleotide polymorphism array (SNP array) testing after prenatal genetic counseling and signing informed consent forms. Ineligible subjects were excluded in accordance with the Technical Specification for Prenatal Screening and Diagnosis of Fetal Cell-free DNA in Maternal Peripheral Blood (2016)\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. This study was approved by the Hangzhou Women\u0026rsquo;s Hospital Ethics Committee (No. 2019-084-01), and all pregnant women signed informed consent forms strictly in accordance with ethical requirements.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e1.2 Methods\u003c/h2\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e1.2.1 Standard NIPT Detection\u003c/h2\u003e \u003cp\u003eA total of 5 mL of peripheral venous blood was collected from pregnant women, and cell-free fetal DNA (cffDNA) was extracted from maternal plasma for library construction. High-throughput gene sequencing and data analysis were performed using the semiconductor sequencing technology on the Ion Proton platform (Thermo Fisher Scientific, USA) with the BioelectronSeq4000 sequencer to predict the fetal risk ratio of chromosomal abnormalities. The results were expressed as Z-score risk assessment (normal range: -3 to 3). A Z-score\u0026thinsp;\u0026ge;\u0026thinsp;3 or \u0026le; -3 indicated high risk, and a Z-score between \u0026minus;\u0026thinsp;3 and 3 indicated low risk.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e1.2.2 NIPT-Plus Detection\u003c/h2\u003e \u003cp\u003eA total of 10 mL of maternal peripheral blood was collected into EDTA anticoagulant tubes, and plasma was obtained by centrifugation. Plasma cffDNA was isolated and extracted via magnetic bead separation method. After library construction and quantification, high-throughput sequencing was conducted using the NextSeq 550AR sequencer (Illumina, USA). Software-based sequence alignment and analysis were performed; the proportion of each chromosome was calculated by increasing sequencing depth and optimizing algorithms to achieve the detection of chromosomal aneuploidy and microdeletion/microduplication. The results were also evaluated by Z-score risk assessment.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e1.2.3 Amniotic Fluid Cell Chromosomal Karyotyping\u003c/h2\u003e \u003cp\u003eCollected amniotic fluid samples were cultured with the flask culture method for 7\u0026ndash;10 days. Amniotic fluid cells were harvested, processed for slide preparation and G-banding following routine procedures. A total of 30 metaphase chromosome karyotypes were manually analyzed for each sample. Chromosomal karyotype description and diagnosis were performed in accordance with the International System for Human Cytogenomic Nomenclature (ISCN, 2020).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e1.2.4 Single Nucleotide Polymorphism (SNP) Array Analysis\u003c/h2\u003e \u003cp\u003eGenomic DNA was extracted and subjected to whole-genome amplification, labeling, hybridization and scanning using the Cytoscan 750K SNP array whole-genome chip (Affymetrix, USA) in strict accordance with the manufacturer\u0026rsquo;s operating manual. Scanning results were analyzed by GenomeStudio software (Affymetrix, USA).\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e1.3 Statistical Methods\u003c/h2\u003e \u003cp\u003eData were processed using the SPSS 26.0 statistical software. Count data were presented as frequency and percentage. The chi-square (χ\u0026sup2;) test was used for intergroup comparison, and a P value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e1.4 Follow-up of Pregnancy Outcomes\u003c/h2\u003e \u003cp\u003eAll pregnant women were followed up by reviewing medical records, accessing the Hangzhou Community Health Information System and conducting telephone interviews. Follow-up contents included fetal prenatal ultrasound findings, method of pregnancy termination, birth defects, gestational age at delivery, fetal sex and postnatal growth and development status. Routine follow-up was completed within 3 months after pregnancy termination or delivery.\u003c/p\u003e \u003c/div\u003e"},{"header":"2.Results","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n \u003ch2\u003e2.1 Prenatal Diagnosis Results\u003c/h2\u003e\n \u003cp\u003eAll 649 pregnant women with NIPT-indicated high risk of SCA underwent amniotic fluid karyotyping and SNP array testing, and 321 cases were confirmed with SCAs. Among them:328 cases were NIPT-indicated high risk of 45,X, of which 83 cases were confirmed as 45,X abnormality and 13 cases as other chromosomal abnormalities by prenatal diagnosis;252 cases were NIPT-indicated high risk of sex chromosome gain, of which 189 cases were confirmed as sex chromosome gain abnormality and 2 cases as other chromosomal abnormalities; among the 189 confirmed sex chromosome gain cases, 101 cases were NIPT-indicated high risk of 47,XXY (96 cases confirmed as 47,XXY), 90 cases were NIPT-indicated high risk of 47,XXX (56 cases confirmed as 47,XXX and 1 case as other chromosomal abnormalities), and 61 cases were NIPT-indicated high risk of 47,XYY (39 cases confirmed as 47,XYY and 1 case as other chromosomal abnormalities);69 cases were NIPT-indicated high risk of X-chromosome copy number variation (CNV), of which 47 cases were confirmed as X-chromosome CNV abnormality and 3 cases as other chromosomal abnormalities.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n \u003ch2\u003e2.2 Positive Predictive Value (PPV) of NIPT\u003c/h2\u003e\n \u003cp\u003eAmong the 649 pregnant women with NIPT-indicated high risk of SCA, 321 cases were true positive, with an overall PPV of 49.46%. The PPV of NIPT for high risk of sex chromosome aneuploidy loss and gain was 25.30% (83/328) and 75.79% (191/252), respectively. The PPV of the sex chromosome aneuploidy gain group was significantly higher than that of the sex chromosome aneuploidy loss group (75.79% vs 25.30%, \u0026chi;\u0026sup2;=116.6, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The PPV of the X-chromosome gain group was significantly higher than that of the X-chromosome loss group (78.39% [156/199] vs 28.02% [109/389], \u0026chi;\u0026sup2;=114.6, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\n \u003cp\u003eFurther subgroup analysis showed that the PPV of NIPT for high risk of 45,X, 47,XXY, 47,XXX, 47,XYY and X-chromosome CNV was 25.30%, 95.05%, 62.22%, 63.93% and 68.12%, respectively (see Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eEfficacy evaluation of NIPT for screening fetal sex chromosomal abnormalities\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"6\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSCA type\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNIPT positive\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePrenatal diagnosis confirmed abnormal\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eConfirmed normal\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDiscordant abnormalities\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePPV(%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45,X\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e328\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e232\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25.30%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47,XXX\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e62.22%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47,XYY\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e63.93%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47,XXY\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e101\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e95.05%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eX chromosome CNV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e68.12%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e649\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e321\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e310\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e49.46%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eIn addition, 18 cases with discordant results between prenatal diagnosis and NIPT were identified incidentally, including 2 cases of pathogenic variants (1 de novo variant verified by parental peripheral blood SNP array testing) and 16 cases of variants of uncertain clinical significance (VOUS). Further parental peripheral blood SNP array verification was performed for 7 cases, revealing 2 de novo variants and 5 maternally inherited variants (see Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eDetails of 18 cases with discordant results between NIPT and fetal SNP array detection\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003enumber\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNIPT bear fruit\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSNP bear fruit\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePrenatal diagnosis conclusion\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003epregnancy outcome\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNIPT result\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSNP array result\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePrenatal diagnosis conclusion\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePregnancy outcome\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2q37.2q37.3 deletion (1.9 Mb), de novo variant\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVariant of uncertain clinical significance (VOUS)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA female infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15q11.2q13.1 duplication (5.3 Mb), de novo variant\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA female infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17p13.3dup780.5Kb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA female infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16p11.2 deletion (761.4 Kb), maternally inherited\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA male infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9p24.1 duplication (646.0 Kb), double duplication\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA male infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8q21.3 deletion (486 Kb)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA female infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1q21.1 duplication (2.644 Mb) and 1q21.2 duplication (1.282 Mb)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFetal death, multiple fetal anomalies (suspected fetal tuberous sclerosis), cardiac rhabdomyoma\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16p13.11 duplication (307.7 Kb), maternally inherited\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA female infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7q21.11 duplication (314.4 Kb), maternally inherited\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA female infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome gain\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5p15.2 duplication (949.5 Kb)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA male infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003echrX:dup:2M-12M\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15q14 duplication (608.7 Kb)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA male infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16p13.11 duplication (827.2 Kb)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA female infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2q31.2 duplication (561.5 Kb)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA female infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6q16.1 duplication (2.1 Mb), maternally inherited\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA female infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10q21.1 deletion (1.6 Mb)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA female infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome gain\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1q43 duplication (171.2 Kb)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA male infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex chromosome gain\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16p11.2 duplication (804 Kb)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVOUS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA male infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eXp22.33-p22.31del7Mb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17q12 duplication (1.9 Mb), maternally inherited\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003epathogenic variation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA male infant was delivered with normal growth and development\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e\n \u003ch2\u003e2.2.1 Stratification by maternal age\u003c/h2\u003e\n \u003cp\u003eAmong the 649 pregnant women with NIPT-indicated high risk of SCA, the maternal age distribution showed 185 cases of advanced maternal age (AMA, defined as gestational age at delivery\u0026thinsp;\u0026ge;\u0026thinsp;35 years) and 464 cases of non-advanced maternal age (non-AMA). The number of non-AMA pregnancies with NIPT-indicated high risk of SCA was relatively higher than that of AMA pregnancies.\u003c/p\u003e\n \u003cp\u003eFurther prenatal diagnosis confirmed positive cases in 100 AMA cases and 219 non-AMA cases, with a PPV of 54.05% (100/185) and 47.20% (219/464), respectively. Chi-square test was performed to analyze the correlation between the AMA and non-AMA groups, and no statistically significant difference was observed between the two groups (\u0026chi;\u0026sup2;=1.998, P\u0026thinsp;\u0026asymp;\u0026thinsp;0.157\u0026thinsp;\u0026gt;\u0026thinsp;0.05).Subgroup analysis by SCA subtype revealed the following PPVs in the AMA vs. non-AMA groups:45,X: 22.37% (17/76) vs. 26.19%(66/252);47,XXY:95.47%(45/47)vs.94.44%(51/54);X-chromosome gain: 79.52% (66/83) vs. 78.45% (91/116);X-chromosome loss: 27.59% (24/87) vs. 33.77% (102/302).No statistically significant differences were identified between the AMA and non-AMA groups in all the above subgroups.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e\n \u003ch2\u003e2.2.2 Stratification by clinical indication for NIPT testing\u003c/h2\u003e\n \u003cp\u003eThe clinical indications for NIPT testing in the 649 pregnant women with NIPT-indicated high risk of fetal SCA were ranked in descending order as follows: abnormal serological screening for Down syndrome, advanced maternal age, voluntary request for NIPT testing, and abnormal ultrasound soft markers, accounting for 43.61% (222/509), 27.70% (141/509), 18.27% (93/509) and 6.48% (33/509), respectively.The number of cases confirmed with abnormalities by further prenatal diagnosis in each group was 97, 74, 43 and 20, with corresponding PPVs of 43.69% (97/222), 52.48% (74/141), 46.24% (43/93) and 60.61% (20/33), respectively. No statistically significant differences were found among all the above groups (see Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003eTable 3 Detection efficiency of NIPT for various SCA subtypes stratified by clinical indications Panel A\u003c/p\u003e\n \u003cdiv align=\"center\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"608\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNIPT indication\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOverall\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e45.X\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 40px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e47.XXY\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHigh-risk\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTrue positive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPV\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHigh-risk\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTrue positive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPV\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHigh-risk\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTrue positive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 40px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPV\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003eAdvanced maternal age (\u0026gt;35 years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e185\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e54.05%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e22.37%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 40px;\"\u003e\n \u003cp\u003e95.74%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003eAbnormal serological screening results\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e247\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e112\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e45.34%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e142\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e26.06%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 40px;\"\u003e\n \u003cp\u003e92.59%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003eAbnormal soft ultrasound markers\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e63.41%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e43.48%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 40px;\"\u003e\n \u003cp\u003e100.00%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003evoluntary request\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e176\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e46.02%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e21.84%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 40px;\"\u003e\n \u003cp\u003e95.45%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 40px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e649\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e319\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e49.15%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e328\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 63px;\"\u003e\n \u003cp\u003e25.30%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 43px;\"\u003e\n \u003cp\u003e101\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 55px;\"\u003e\n \u003cp\u003e96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 40px;\"\u003e\n \u003cp\u003e95.05%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003ePanel B (Continued)\u003c/p\u003e\n \u003cdiv align=\"center\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"612\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNIPT indication\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 39px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e47,XXX\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e47,XYY\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eX-chromosome CNV\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHigh-risk\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTrue positive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPV\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHigh-risk\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTrue positive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPV\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHigh-risk\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTrue positive\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePPV\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003eAdvanced maternal age (\u0026gt;35 years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e60.61%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e66.67%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e57.14%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003eAbnormal serological screening results\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e58.06%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e42.86%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e78.79%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003eAbnormal soft ultrasound markers\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e100.00%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e85.71%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e66.67%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003evoluntary request\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e65.22%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e60.00%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e57.89%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 134px;\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 39px;\"\u003e\n \u003cp\u003e62.22%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e63.93%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 46px;\"\u003e\n \u003cp\u003e69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 60px;\"\u003e\n \u003cp\u003e68.12%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\u003c/table\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec16\" class=\"Section3\"\u003e\n \u003ch2\u003e2.2.3 Efficacy evaluation of NIPT in screening fetal X-chromosome copy number variations (CNVs)\u003c/h2\u003e\n \u003cp\u003eAmong the 649 cases with NIPT-indicated high risk of SCA, 69 cases were identified with high risk of X-chromosome CNV abnormalities, of which 47 cases were confirmed as X-chromosome CNV abnormalities and an additional 3 cases as other chromosomal abnormalities by further prenatal diagnosis.\u003c/p\u003e\n \u003cp\u003eOf the 69 NIPT-indicated high-risk cases for X-chromosome CNVs, 61 cases were high risk of X-chromosomal segment deletion, with 43 cases confirmed abnormal by prenatal diagnosis, yielding a PPV of 70.49% (43/61); 8 cases were high risk of X-chromosomal segment duplication, with 4 cases confirmed abnormal by prenatal diagnosis, with a PPV of 50.00% (4/8).\u003c/p\u003e\n \u003cp\u003eAmong the 43 cases confirmed with X-chromosomal deletion by prenatal diagnosis, the abnormalities included 27 cases of Xp22.31 segment deletion, 8 cases of Xp22.33 deletion (including 3 cases of mosaic Xp22.31 segment deletion), and 8 cases of other X-chromosomal segment deletions. The deletion fragment size of the Xp22.31 segment was concentrated at approximately 1.68 Mb, and that of the Xp22.33 segment ranged from 21.5 to 58.3 Mb. The remaining 8 cases of other X-chromosomal segment deletions involved the Xq26.1q28, Xq22.1q22.3, Xq23q28 and Xq26.2q28 regions, as well as three large-segment deletions in the long and short arms of the X chromosome. The 4 cases confirmed with X-chromosomal segment duplication included the Xq11.1q28, Xp22.33 and Xp22.31 regions, all of which were pathogenic variants.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\n \u003ch2\u003e2.4 Pregnancy outcomes\u003c/h2\u003e\n \u003cp\u003eAll 649 pregnant women with NIPT-indicated high risk of SCA were successfully followed up with no lost to follow-up cases. Among the 321 true positive cases, 155 cases underwent induced labor, and 166 cases achieved live birth with normal neonatal growth and development.\u003c/p\u003e\n \u003cp\u003eAmong the 18 cases with discordant results between NIPT and prenatal diagnosis, 1 case underwent induced labor, 1 case suffered fetal death due to multiple fetal anomalies, and 16 cases had normal delivery; the neonates showed normal growth and development at the 6-month postnatal follow-up.\u003c/p\u003e\n \u003cp\u003eAmong the 310 false positive cases, 5 cases underwent induced labor, including 2 cases due to subsequent abnormal ultrasound findings, 1 case due to homozygous mutation of fetal deafness gene detected by amniocentesis, 1 case due to severe preeclampsia, and 1 case for personal reasons. One neonate was diagnosed with multiple anomalies after birth, including anal atresia, ventricular septal defect, atrial septal defect, micrognathia, high-arched palate and glossoptosis. The remaining 304 cases had normal delivery with normal growth and development.\u003c/p\u003e\n \u003cp\u003eAmong the 321 cases with confirmed SCAs, the live birth rates of 47,XXX, 47,XXY, 45,X, 47,XYY and X-chromosome CNV abnormalities were 80.36% (45/56), 20.83% (20/96), 48.19% (40/83), 76.92% (30/39) and 63.83% (30/47), respectively. These results indicated that pregnant women carrying fetuses with 47,XYY, 47,XXX and X-chromosome CNV abnormalities were more likely to choose to continue the pregnancy compared with those with 45,X and 47,XXY abnormalities.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"3 Discussion","content":"\u003cp\u003eAs a high-throughput, non-invasive detection method with high sensitivity and specificity for trisomy 21 (T21), trisomy 18 (T18) and trisomy 13 (T13)\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e, non-invasive prenatal testing (NIPT) has become one of the most commonly used prenatal screening technologies at present. Besides common chromosomal aneuploidies, sex chromosomal abnormalities (SCAs) represent another major category of genetic factors leading to birth defects. The incidence of fetal sex chromosome aneuploidies in human embryos is higher than that of trisomy 21, among which 45,X has the highest incidence of 1%\u0026ndash;1.5%\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. As a first- or second-line screening strategy for common fetal trisomies, NIPT exhibits high sensitivity and specificity, and it is also capable of detecting SCAs (including rare abnormalities)\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. This study retrospectively analyzed 649 cases with NIPT-indicated high risk of SCA in our center, where 47,XXY, 47,XXX, 47,XYY, 45,X and X-chromosome copy number variation (CNV) abnormalities were the major subtypes. The results showed an overall positive predictive value (PPV) of 49.46%, with 47,XXY presenting the highest PPV, which is consistent with the findings of previous studies\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Proportion and clinical significance of different NIPT indications\u003c/h2\u003e \u003cp\u003eIn terms of clinical indications for NIPT, abnormal serological screening and advanced maternal age (AMA) accounted for the highest proportions. A total of 247 cases with NIPT-indicated high risk of SCA were identified in pregnant women with abnormal maternal serological screening (including high risk, critical risk and abnormal biochemical indicators) as the primary indication, accounting for 38.06% (247/649), among which 114 cases were confirmed positive by further prenatal diagnosis with a PPV of 46.15% (114/247). A total of 185 cases with NIPT-indicated high risk of SCA were found in pregnant women with AMA as the primary indication, accounting for 28.51% (185/649), with 100 confirmed positive cases and a PPV of 54.05% (100/185). These results were consistent with numerous previous studies\u003csup\u003e[\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e, directly reflecting that these two populations are the core target groups for SCA screening by NIPT, which is mainly attributed to the matching between the design of prenatal screening system and the risk characteristics of the population.\u003c/p\u003e \u003cp\u003eThe high proportion of abnormal serological screening as an indication is primarily due to the relatively high false positive rate of serological screening; however, abnormal results prompt most pregnant women to choose NIPT for further examination, and this high conversion rate leads to a large volume of NIPT tests in this population. In addition, serological screening is widely used as an initial clinical screening method, resulting in a much larger base of pregnant women with abnormal screening results than other indications. Precisely because of the high proportion of maternal serological screening, NIPT, as a highly accurate screening method, can further improve the detection rate of SCAs in pregnant women with abnormal serological screening results.\u003c/p\u003e \u003cp\u003eThe high proportion of AMA as an indication is mainly due to the positioning of AMA pregnant women as a high-risk group for overall chromosomal abnormalities and their low acceptance of invasive prenatal diagnosis, leading to a higher density of NIPT screening in this population. Studies have shown that AMA exerts differential effects on different types of SCAs\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e: for instance, the incidence of 45,X and 47,XYY is unrelated to maternal age, while AMA significantly increases the fetal incidence of 47,XXX and 47,XYY\u003csup\u003e[\u003cspan additionalcitationids=\"CR19 CR20 CR21\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. Therefore, in clinical genetic counseling, personalized risk assessment should be provided based on different SCA subtypes, combined with maternal age and screening indications.\u003c/p\u003e \u003cp\u003eIn the data of this study, we also found 41 cases with abnormal ultrasound soft markers as the clinical indication among NIPT high-risk cases, and 26 fetuses were finally diagnosed with SCAs, with a PPV of 63.41%, which was superior to other indications. Further subtype analysis revealed that the PPV of the sex chromosome gain group in this indication reached as high as 93.33% (14/15). Thus, for NIPT-positive pregnant women with this indication, we recommend early acceptance of further prenatal diagnosis to avoid missed diagnosis.\u003c/p\u003e \u003cp\u003eAccordingly, we conclude that pregnant women with abnormal serological screening and AMA are the main target groups for fetal SCA screening by NIPT, and abnormal ultrasound soft markers can serve as an important auxiliary method for fetal SCA screening.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Positive predictive value (PPV)\u003c/h2\u003e \u003cp\u003eIn this study, among 649 cases with NIPT-indicated high risk of fetal SCA, prenatal diagnosis confirmed 321 true positive cases, with an overall PPV of 49.46% (321/649), which was basically consistent with the 40%\u0026ndash;77% reported in the literature\u003csup\u003e[\u003cspan additionalcitationids=\"CR24\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e. The PPV of NIPT varied across different SCA subtypes: previous studies reported a PPV of approximately 47.8%\u0026ndash;55.56% for 47,XXX, 17.50%\u0026ndash;32.43% for 45,X, 56.52%\u0026ndash;60% for 47,XXY, and 50%\u0026ndash;87.50% for 47,XYY\u003csup\u003e[\u003cspan additionalcitationids=\"CR27\" citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e. In this study, the PPV of 47,XXY was as high as 95.05%, and the PPVs for 47,XXX, 47,XYY and X-chromosome CNV abnormalities were 62.22%, 63.93% and 68.12%, respectively. In contrast, the PPV of 45,X was only 25.30%, indicating that NIPT performs better in predicting sex chromosome trisomies than X monosomy. This may be attributed to the following reasons\u003csup\u003e[\u003cspan additionalcitationids=\"CR30 CR31\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e: the X chromosome harbors 1098 genes and the Y chromosome 78 genes, among which 58 are homologous genes on both sex chromosomes, and most of these genes (29 genes) are located at the terminal regions of sex chromosomes; the low guanine-cytosine (GC) content of the X chromosome leads to highly variable amplification of the X chromosome; non-random X-chromosome inactivation in placental tissues may account for the low PPV of Turner syndrome (45,X), with the paternal X chromosome tending to be inactivated in XX female trophoblast cells. In addition, age-related X-chromosome loss has been reported in leukocytes of normal women, which may affect the accuracy of fetal 45,X prediction by NIPT\u003csup\u003e[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eFurthermore, in this study, the PPV of NIPT for high risk of sex chromosome loss and gain was 25.30% (83/328) and 75.79% (191/252), respectively (χ\u0026sup2;=145.7, P\u0026lt;0.001), indicating that NIPT has a better predictive value for sex chromosome gain than loss. The PPV of NIPT for high risk of X-chromosome loss and gain was 32.39% (126/389) and 78.39% (156/199), respectively (χ\u0026sup2;=111.6, P\u0026lt;0.001), demonstrating a superior predictive value for X-chromosome gain over loss. In view of the high PPV of NIPT for screening sex chromosome gain and X-chromosome CNV abnormalities, as well as the high false positive rate for 45,X, we recommend that NIPT reports provide specific SCA subtypes to facilitate appropriate clinical counseling and recommendations based on different subtypes.\u003c/p\u003e \u003cp\u003eAdditionally, although the overall PPV of the AMA group was slightly higher than that of the non-AMA group (54.05% vs 47.63%, χ\u0026sup2;=1.96, P\u0026thinsp;\u0026asymp;\u0026thinsp;0.161\u0026thinsp;\u0026gt;\u0026thinsp;0.05), no statistically significant difference was observed. There were no significant differences in the PPV of each SCA subtype between the AMA and non-AMA groups, suggesting that maternal age is not a major influencing factor for NIPT prediction of SCAs, which is consistent with previous research\u003csup\u003e[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/sup\u003e. No significant differences in the PPV of NIPT for SCAs were found among populations with different clinical indications, and further analysis of the PPV for each SCA subtype also revealed no notable disparities. Therefore, the PPV of NIPT for SCA screening has no significant correlation with clinical detection indications.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003e3.3 X-chromosome copy number variation (CNV) abnormalities\u003c/h2\u003e \u003cp\u003eThis study specifically analyzed data of NIPT-indicated high risk of X-chromosome CNV abnormalities and found a PPV of 67.92% (36/53), second only to 47,XYY, with most cases being X-chromosome microdeletion abnormalities (PPV\u0026thinsp;=\u0026thinsp;69.39%, 34/49). Analysis of 36 true positive cases with X-chromosome CNV abnormalities showed that the abnormalities mainly involved deletions in the Xp22.31 and Xp22.33 regions, all of which were pathogenic variants with variable deletion fragment sizes. Phenotypic abnormal syndromes associated with Xp22.3 depend on the range and nature of deleted or duplicated genes. The loci of Xp22.3 microdeletions/microduplications were almost identical, a phenomenon known as recurrent copy number variations. In this study, the deletion fragment size of the Xp22.31 region was concentrated at approximately 1.68 Mb, which is consistent with previous research\u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e reporting that \"approximately 70% of Xp22.3 microdeletions are recurrent Xp22.3 microdeletions with a fragment size of about 1.6 Mb, mainly involving the STS gene and flanking segments\". Xp22.3 microdeletion in male fetuses is associated with X-linked ichthyosis (XLI, OMIM 308100).\u003c/p\u003e \u003cp\u003eWe also found that the PPV of X-chromosome CNV abnormalities was as high as 76% (19/25) in the population with abnormal serological screening as the NIPT indication, and 75% (6/8) in cases with abnormal serological multiple of the median (MoM) values. This suggests that X-chromosome CNV abnormalities may be associated with serological indicators, which is consistent with the finding by Langlois et al.\u003csup\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e that maternal serum unconjugated estriol (uE3) MoM value\u0026thinsp;\u0026lt;\u0026thinsp;0.25 is correlated with Xp22.3 microdeletion. This may be because fetal Xp22.3 microdeletion may cause loss of the STS gene, which impairs sulfatase activity in the placenta and further leads to decreased uE3 concentration in amniotic fluid\u003csup\u003e[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn conclusion, NIPT has a relatively high PPV for fetal X-chromosome CNV abnormalities, especially in the population with abnormal serological screening, which can provide a reference for clinical genetic counseling.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Pregnancy outcome choices for fetuses with SCA abnormalities\u003c/h2\u003e \u003cp\u003eFollow-up of pregnancy outcomes for fetuses with SCAs showed that after excluding lost-to-follow-up cases, the live birth rates of 47,XXX, 47,XYY, X-chromosome CNV, 45,X and 47,XXY abnormalities were 80.00%, 73.33%, 63.89%, 36.20% and 23.29%, respectively. We found that pregnant women carrying fetuses with 47,XXX or 47,XYY were more likely to choose to continue the pregnancy. Multiple factors influence pregnancy decision-making, including conception method, adverse pregnancy and childbirth history, parental age, educational level, religious belief, social culture, economic status, fertility, number of existing children, expectation, parental perception of the anticipated disease, and even emotional stability during decision-making\u003csup\u003e[\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]\u003c/sup\u003e, among which the severity of clinical phenotype is the most critical. 47,XXX and 47,XYY are associated with relatively mild phenotypes, while 45,X and 47,XXY often present with severe clinical phenotypes such as abnormal sexual development, reduced fertility and abnormal secondary sexual characteristic development, which are less acceptable to parents. The severity of clinical phenotypes of X-chromosome CNV abnormalities depends on the size and pathogenicity of the deleted/duplicated fragments. In this study, most X-chromosome CNV abnormalities were Xp22.31 region deletions with small fragment sizes and mild clinical phenotypes, resulting in a relatively high live birth rate. Therefore, NIPT reports are recommended to specify the SCA subtype, and provide fragment size if X-chromosome CNV abnormalities are involved, to assist pregnancy decision-making for pregnant women.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Incidentally detected CNV abnormalities\u003c/h2\u003e \u003cp\u003eIn this study, 18 cases of autosomal CNV abnormalities were incidentally detected by prenatal diagnosis among NIPT-indicated SCA high-risk cases. Among the pregnancy outcomes, 1 case had fetal death due to multiple fetal anomalies, 1 case underwent induced labor, and the remaining cases achieved live birth with no obvious neonatal abnormalities. Of these 18 SCA high-risk cases, 13 were NIPT-indicated for sex chromosome loss, further indicating a high false positive rate of NIPT for sex chromosome loss. However, clinicians should not abandon further prenatal diagnosis for this group due to the high false positive rate.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Conclusion\u003c/h2\u003e \u003cp\u003eIn summary, NIPT has high clinical value in screening fetal sex chromosomal abnormalities, especially for sex chromosome 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 fetal sex chromosomal abnormalities.\u003c/p\u003e \u003cp\u003eIn this retrospective analysis of the detection efficacy of NIPT for fetal SCAs, we included X-chromosome CNV abnormalities in the analysis, which fills the domestic and international data gap of NIPT in this field. However, this study is a single-center research with a relatively small sample size, and the findings need to be verified by multicenter, large-sample studies.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003e This study involving human participants was conducted in accordance with the ethical standards of the Medical Ethics Committee of Hangzhou Women\u0026rsquo;s Hospital Ethics Committee (No. 2019-084-01) and the 1964 Helsinki Declaration. As this was a retrospective study,writteninformed consent was obtained from patients at the time of clinical care, and all data were analyzed anonymously.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eARTICLE IN PRESS\u003c/p\u003e \u003cp\u003eMedical and Health Research Project of Meizhou City (No.2024-B-27).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eQiuhong Huang:Project development, Data Collection, Manuscript writing. FengdanLai: Data analysis, Liubing Lan: Data Collection,Qiuhong Huang:Manuscript editing.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used during the present study are available from the correspondingauthor upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBoyd PA, Loane M, Garne E, Boyd PA, Loane M, Garne E, et al. Sex chromosome trisomies in Europe: prevalence, prenatal detection and outcome of pregnancy[J]. Eur J Hum Genet. 2011;19(2):231\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVisootsak J, Graham JM. Klinefelter syndrome and other sex chromosomal aneuploidies[J]. Orphanet J Rare Dis. 2006;1:42.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePieters JJ, Verhaak CM, Braat DD, Pieters JJ, Verhaak CM, Braat DD, et al. 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J Pediatr Adolesc Gynecol. 2018;31(6):651\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXu Y, Chen L, Liu Y, Hao Y, Xu Z, Deng L, Xie J. Screening, prenatal diagnosis, and prenatal decision for sex chromosome aneuploidy. Exp Rev Mol Diagnost. 2019;19(6):537\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLu X, Wang C, Sun Y, Tang J, Tong K, Zhu J, Wang C, Sun Y, Tang J, Tong K, Zhu J. Noninvasive prenatal testing for assessing foetal sex chromosome aneuploidy: a retrospective study of 45,773 cases. Mol Cytogenet. 2021;14(1):1\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJimenez Vaca AL, Valdes-Flores Mdel R, Rivera-Vega MR, Jimenez Vaca AL, Valdes-Flores Mdel R, Rivera-Vega MR, et al. Deletion pattern of the STS gene in X-linked ichthyosis in a Mexican population[J]. Mol Med. 2001;7(12):845\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLanglois S, Armstrong L, Gall K, et al. Steroid sulfatase deficiency and contiguous gene deletion syndrome amongst pregnant patients with low serum unconjugated estriols [J]. Prenat Diagn. 2009;29(10):966\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZeng Y, Jianjun Z. Research progress of Xp22.3 microdeletion/microduplication [J]. Chin J Med Genet. 2020;37(5):584\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang Chengchu W, Yousheng L, Jian Y, Jiexia W, Xingwang C, Hanbiao Y, Aihua. Prenatal diagnostic indications, pregnancy outcomes and influencing factors in 1 372 pregnant women with fetal sex chromosome aneuploidy [J]. Chin J Perinat Med. 2022;25(12):942\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Non-invasive prenatal testing, Copy number variation, Pregnancy outcomes, Positive predictive value, Prenatal diagnosis, Karyotype analysis, Chromosomal microarray analysis","lastPublishedDoi":"10.21203/rs.3.rs-8509814/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8509814/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eTo 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.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA 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.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAmong 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%, χ\u0026sup2;=111.6, P\u0026lt;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%, χ\u0026sup2;=1.96, P\u0026thinsp;\u0026asymp;\u0026thinsp;0.161\u0026thinsp;\u0026gt;\u0026thinsp;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.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eNIPT 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.\u003c/p\u003e","manuscriptTitle":"Prenatal diagnosis and pregnancy outcome of 649 high-risk fetuses with noninvasive prenatal testing for sex chromosome abnormalities","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-02 18:47:51","doi":"10.21203/rs.3.rs-8509814/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-14T15:28:16+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-11T10:10:47+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-10T22:17:33+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-12T19:30:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"211988127024241288667874647564225791849","date":"2026-02-11T07:01:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"267563550210792735573680628557858349646","date":"2026-02-09T11:43:28+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-08T20:08:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"295610221373128006803434170319915085626","date":"2026-02-08T19:56:56+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-08T19:09:45+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"268264660386072494156848319151624951497","date":"2026-02-07T11:35:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"294199101678579722710097116862553899621","date":"2026-02-06T19:38:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"237894870093868502285122482639921796992","date":"2026-02-06T19:07:51+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-29T11:46:07+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-01-06T12:08:50+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-06T10:03:08+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-06T10:01:28+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pregnancy and Childbirth","date":"2026-01-04T02:36:33+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"1a19d888-483f-4883-a75d-f9ebc4ae1477","owner":[],"postedDate":"February 2nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-04-14T15:40:56+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-02 18:47:51","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8509814","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8509814","identity":"rs-8509814","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}