Approach and Management of Pregnancies with Risk Identified by Non-Invasive Prenatal Testing

This study represents our second investigation into NIPT, involving a more extensive patient cohort with a specific emphasis on the high-risk group. The high-risk group was subsequently divided into two further groups to compare confirmed cases versus unconfirmed via direct methods. The methodology encompassed the analysis of 1400 consecutive cases from a single genetic center in western Romania, where NIPT was used to assess the risk of specific fetal chromosomal abnormalities. All high-risk cases underwent validation through direct analysis of fetal cells obtained via invasive methods, including chorionic villus sampling and amniocentesis. The confirmation process utilized QF-PCR, karyotyping, and SNP-Array methods customized to each case. Results: A high risk of aneuploidy at NIPT was identified in 36 out of 1400 (2.57%) cases and confirmed in 28 cases. The study also detected an increased risk for copy number variations (CNVs) in 1% of cases, confirmed in two instances involving one large microdeletion and one large microduplication. Trisomy 21 was the exclusive anomaly where NIPT confirmed all cases with identified risk. High-risk NIPT results which were not validated by invasive methods, were classified as false positives; parents in these cases determined to continue the pregnancy. In conclusion, NIPT can serve as a screening method for all pregnancies; however, in high-risk cases, an invasive confirmation test is strongly recommended.

Prenatal diagnosis, pregnancy determination and follow up of sex chromosome aneuploidy screened by non-invasive prenatal testing from 122 453 unselected singleton pregnancies: A retrospective analysis of 7-year experience

The phenotype of SCA patients are diversities, make prenatal counseling and parental decision-making following the prenatal diagnosis of SCA more complicated and challenging. NIPT has higher sensitivity and specificity in screening trisomy 21 syndrome, but the effectiveness of NIPT in detecting SCA is still controversial. This study is a large-scale retrospective cohort of positive SCA screened from unselected singleton pregnancies by non-invasive prenatal testing (NIPT) from a single prenatal center of a tertiary hospital. Clinical information, indications, diagnostic results, ultrasound findings, pregnancy determinations, and follow-up were reviewed and analyzed. 596 cases of SCA positive were screened out of 122 453, giving a positive detection rate of 0.49%. 510 cases (85.6%) conducted with amniocentesis to detect fetal chromosome, of which 236 were confirmed as true positive of SCA with PPV of 46.3% (236/510). Of the 236 cases confirmed as true positive SCA, 114 cases (48.3%)chose to terminate the pregnancy (93.0%, 65.3%, 15.4% and 10.9% for 45,X, 47,XXY, 47,XXX and 47,XYY, respectively), 122 cases (51.7%) elected to continue the pregnancy. In conclusions, NIPT as a first-tier routine method for screening autosomal aneuploidies, also could play an important role in screening SCA. Low-risk pregnant women are the main indication for the detection of SCA as NIPT test provides to non-selective population. For 47,XXX and 47,XYY with mild phenotype, couples would like to continue the pregnancy. But for 45,X and 47,XXY, parents apt to terminate pregnancy no matter ultrasound abnormalities were found or not.

Innovative insights into extrachromosomal circular DNAs in gynecologic tumors and reproduction

Originating but free from chromosomal DNA, extrachromosomal circular DNAs (eccDNAs) are organized in circular form and have long been found in unicellular and multicellular eukaryotes. Their biogenesis and function are poorly understood as they are characterized by sequence homology with linear DNA, for which few detection methods are available. Recent advances in high-throughput sequencing technologies have revealed that eccDNAs play crucial roles in tumor formation, evolution, and drug resistance as well as aging, genomic diversity, and other biological processes, bringing it back to the research hotspot. Several mechanisms of eccDNA formation have been proposed, including the breakage-fusion-bridge (BFB) and translocation-deletion-amplification models. Gynecologic tumors and disorders of embryonic and fetal development are major threats to human reproductive health. The roles of eccDNAs in these pathological processes have been partially elucidated since the first discovery of eccDNA in pig sperm and the double minutes in ovarian cancer ascites. The present review summarized the research history, biogenesis, and currently available detection and analytical methods for eccDNAs and clarified their functions in gynecologic tumors and reproduction. We also proposed the application of eccDNAs as drug targets and liquid biopsy markers for prenatal diagnosis and the early detection, prognosis, and treatment of gynecologic tumors. This review lays theoretical foundations for future investigations into the complex regulatory networks of eccDNAs in vital physiological and pathological processes.

First Trimester Contingent Screening for Aneuploidies with Cell-Free Fetal DNA in Singleton Pregnancies - a Swiss Single Centre Experience

Introduction

Switzerland was amongst the first countries to offer cell-free fetal DNA (cffDNA) testing covered by the health insurance to pregnant women with a risk ≥ 1:1000 for trisomies at first trimester combined screening (FTCS). The aim of this study is to evaluate the implementation of this contingent model in a single tertiary referral centre and its effect on gestational age at diagnosing trisomy 21.

Materials and Methods

Between July 2015 and December 2020 all singleton pregnancies at 11-14 weeks of gestation without major fetal malformation were included and stratified according to their risk at FTCS. Statistical analysis was performed by GraphPad Version 9.1 for Windows.

Results

4424 pregnancies were included. Of 166 (3.8%) pregnancies with a NT ≥ 3.5 mm and/or a risk ≥ 1:10 at FCTS, 130 (78.3%) opted for direct invasive testing. 803 (18.2%) pregnancies had an intermediate risk, 692 (86.2%) of them opted for cffDNA first. 3455 (78.1%) pregnancies had a risk < 1:1000. 63 fetuses were diagnosed with trisomy 21, 47 (74.6%) directly by invasive procedures after FTCS, 16 (25.4%) by cffDNA first.

Conclusions

Most women choose cffDNA or invasive testing as second tier according to national guidelines. Despite the delay associated with cffDNA testing after FCTS, 75% of all trisomy 21 are still diagnosed in the first trimester with this contingent screening model.

Clinical value of positive CNVs results by NIPT without fetal ultrasonography-identified structural anomalies

OBJECTIVE

To evaluate the clinical value of positive copy number variations (CNVs) results by non-invasive prenatal testing (NIPT) without fetal ultrasonography-identified structural anomalies, especially with several known CNVs results.

METHODS

A total of 135,981 results of NIPT performed between April 1, 2017, and March 31, 2020, enrolled in the free NIPT service program implemented by the local government were retrospectively analyzed. Of these, 87 cases with positive NIPT screens for CNVs and no fetal ultrasonography-identified anomalies were recalled and provided genetic counseling. After obtaining full informed consent, these cases were provided invasive prenatal diagnosis by karyotyping and chromosomal microarray analysis (CMA)/copy number variation sequencing (CNV-seq) with follow-up. One case was lost, while 86 cases were successfully followed up.

RESULTS

A total of 44 (50.6%) cases underwent invasive prenatal diagnosis, of which six cases were detected with abnormal karyotype. CMA/CNV-Seq revealed 11 fetuses with positive results for CNVs, among whom eight were consistent with NIPT results, two were partially consistent, one was inconsistent, and positive predictive value (PPV) was 22.7% (10/44). For known CNVs, PPVs were 20% (15q11.2-q13 microdeletion) and 33.3% (5p end deletions). Among 11 pregnant women with positive prenatal diagnosis, seven were confirmed to have pathogenic CNVs in their fetuses; four had CNVs of unknown clinical significance.

CONCLUSIONS

Even in pregnancies without ultrasonography-identified anomalies, a positive NIPT screen for CNVs must be interpreted with caution and validated by additional diagnostic study.

[Non-Invasive Prenatal Testing:Results in 3733 Cases of Twin Pregnancy and Association With Factors Such as Age]

Objective To explore the clinical significance of non-invasive prenatal testing(NIPT)for fetal chromosomal abnormalities in the cases of twin pregnancy and its relationship with age and other related factors.Methods A total of 3733 women with twin pregnancy of 12-26+6 weeks who voluntarily underwent NIPT in the Ningbo Women and Children's Hospital from January 2018 to December 2022 were selected.The results of NIPT and amniocentesis were compared and all the participants were followed up.The detection rate of chromosomal abnormalities by NIPT was calculated,and its correlations with age,gestational weeks,chorionicity,and pregnancy type were analyzed.Results Among the 3733 cases,71 cases of fetal chromosome abnormality were indicated by NIPT,including 13 cases of trisomy 21,19 cases of trisomy 18,5 cases of trisomy 13,18 cases of sex chromosome abnormality,and 16 cases of chromosome microdeletion/duplication(excluding 21,18,13,and sex chromosomes),among which 34 cases were true positive and 37 cases were false positive.The overall sensitivity,specificity,and positive predictive value(PPV)of NIPT for chromosomal abnormalities in the cases of twin pregnancy were 100%,98.99%,and 47.89%(34/71),respectively.NIPT showed the sensitivity,specificity,and PPV of 100%,99.78%,and 78.38%(29/37)for trisomy 21,18,and 13,100%,99.56%,and 16.67%(3/18)for sex chromosome abnormalities,and 100%,99.62%,and 12.5%(2/16)for chromosome microdeletion/duplication,respectively.In the age group of ≥40 years,the NIPT for chromosomal abnormalities showed the PPV of 66.67%,the sensitivity of 100%,and the misdiagnosis rate of 30%。However,the NIPT for trisomy 21,18,and 13 showed the PPV of 100%,the misdiagnosis rate of 0,and the sensitivity and specificity of 100%.In terms of grouping based on gestational weeks,the NIPT for chromosomal abnormalities showed the highest PPV(51.28%)in the women with twin pregnancy for 14-17+6 weeks,followed by that(50.00%)in the women with twin pregnancy for 22-26+6 weeks;the NIPT for trisomy 21,18,and 13 showed the highest PPV of 94.74% in the gestation group of 14-17+6 weeks,followed by that(83.33%)in the gestation group of 18-21+6 weeks.The rate of dichorionic diamniotic twins was higher in assisted pregnancies than in natural pregnancies,and NIPT showed the same detection efficiency for dichorionic diamniotic twins and monochorionic diamniotic twins and the same detection efficiency for different pregnancy types.Conclusions NIPT has high accuracy in the diagnosis of twin pregnancy and high sensitivity and high specificity for different ages and gestational weeks,especially for trisomy 21,18,and 13.NIPT is suitable for assisted pregnancy and natural pregnancy,and it is of high value in clinical application.However,extensive application needs a large population-based study.

Epigenetic phenotype of plasma cell-free DNA in the prediction of early-onset preeclampsia

BACKGROUND

In the current study, we sought to characterise the methylation haplotypes and nucleosome positioning patterns of placental DNA and plasma cell-free DNA of pregnant women with early-onset preeclampsia using whole genome bisulphite sequencing (WGBS) and methylation capture bisulphite sequencing (MCBS) and further develop and examine the diagnostic performance of a generalised linear model (GLM) by incorporating the epigenetic features for early-onset preeclampsia.

METHODS

This case-control study recruited pregnant women aged at least 18 years who delivered their babies at our Hospital. In addition, non-pregnant women with no previous history of diseases were included. Placental samples of the villous parenchyma were taken at the time of delivery and venous blood was drawn from pregnant women during non-invasive prenatal testing at 12-15 weeks of pregnancy and nonpregnant women during the physical check-up. WGBS and MCBS were carried out of extracted genomic DNA. Then, we established the GLM by incorporating preeclampsia-specific methylation haplotypes and nucleosome positioning patterns and examined the diagnostic performance of the model by receiver operating characteristic (ROC) curve analysis.

RESULTS

The study included 135 pregnant women and 50 non-pregnant women. Our high-depth MCBS revealed notably different DNA methylation and nucleosome positioning patterns between women with and without preeclampsia. Preeclampsia-specific hypermethylated sites were found predominantly in the promoter regions and particularly enriched in CTCF on the X chromosome. Totally, 2379 preeclampsia-specific methylation haplotypes were found across the entire genome. ROC analysis showed that the area under the ROC curve (AUC) was 0.938 (95%CI 0.877, 1.000). At a GLM cut-off of 0.341, the AUC was the maximum, with a sensitivity of 95.6% and a specificity of 89.7%.

CONCLUSION

Pregnant women with early-onset preeclampsia exhibit DNA methylation and nucleosome positioning patterns in placental and plasma DNA.

Evaluation of pre-test counselling offered for non-invasive prenatal testing (NIPT) as a primary screening tool

The increasing popularity and expansion of non-invasive prenatal testing (NIPT) to screen for rare conditions beyond common trisomies prompts evaluation of pre-test counselling currently offered. We conducted a prospective survey to assess women's knowledge of NIPT in those who had undergone NIPT (study group) and those who were planning to have NIPT (control group). Out of the 189 questionnaires analysed, the study group did not show a higher knowledge score compared to the control group (P = 0.097). 44% misunderstood that NIPT can identify more conditions than invasive testing, 69.8% were unaware of the recommended need for nuchal translucency measurement and 52.6% were unaware of the possibility of incidental findings. 31% even considered discussing termination of pregnancy as one of the next steps if NIPT shows high risk for Down syndrome. This study shows that current pre-test counselling is inadequate. Service providers should address these knowledge gaps and assist women to make informed choices.Impact StatementWhat is already known on this subject? Pre-test counselling for non-invasive prenatal testing (NIPT) should be conducted to assist women in making an informed consent.What do the results of this study add? Our results show that a significant proportion of women are unaware of the limitations of NIPT.What are the implications of these findings for clinical practice and/or further research? Service providers should improve their pre-test counselling focusing on areas of knowledge deficiencies and misunderstanding on NIPT identified in this study.

Women's preferences for NIPT as a first-line test in England and France: Challenges for genetic counseling practices

Non-invasive prenatal testing (NIPT) is provided in the private and public sectors worldwide as a first- or second-tier test. In England and France, NIPT is fully funded and offered as a contingent strategy with different probability cut-offs (1:150 and 1:1000). These different approaches to define the target population for NIPT have implications for how women experience their antenatal care. The paper explores and compares the perceptions and difficulties of women in England and France who took NIPT as a second-tier screening test. It is based on a semi-structured qualitative interview study with 17 women in England and France conducted between September 2021 and May 2022. The interviews were cross-analyzed using thematic analysis. Our findings show that most women express a preference for the offer of NIPT as a first-line screening test. Some issues with the contingent model, related to the access to information and termination of pregnancy (TOP), the disparities of NIPT uptake, and risks of generating anxiety with combined first-trimester screening (cFTS), could be addressed by a universal strategy for T21, T13, and T18. Nevertheless, this strategy could present some challenges for genetic counseling due to: women's understanding and expectations of NIPT; adequate information and counseling about the scope and limits of NIPT; concerns about the routinization of NIPT in the first-line offer; limitations and uncertainties associated with the provision of expanded NIPT in France; the remaining importance of other screening tests; and associated costs.

Understanding knowledge, perception, and willingness of non-invasive prenatal testing for fetal aneuploidy: a survey among Chinese high-risk pregnant women

Objectives

Non-invasive prenatal testing (NIPT) is utilized for screening the likelihood of fetal aneuploidy, presenting the benefits of non-invasiveness, high sensitivity, and specificity. Its application in prenatal screening has become ubiquitous. The inquiry into how pregnant women comprehend and determine NIPT screening strategies is paramount. Regrettably, there has been a dearth of research on this subject in China. Consequently, this study scrutinizes pregnant women's cognizance and perspectives concerning NIPT, furnishing a foundation for advancing its judicious implementation.

Methods

From February 2021 to December 2022, a questionnaire survey was conducted among pregnant women receiving prenatal care and screening at the Women's Hospital, School of Medicine, Zhejiang University, who were randomly selected from a pool of individuals exhibiting a high risk of fetal aneuploidy on serological screening. The survey aimed to gather data on participant characteristics, knowledge, perception, and willingness concerning NIPT. The study employed chi-square and Kruskal Wallis tests to analyze subgroup differences.

Results

A total of 226 valid questionnaires were obtained. 83.2% of women pregnant women identified as high risk by serological screening would opt for NIPT, with 66.4% indicating that they would prefer NIPT for fetal aneuploidy screening in future pregnancies. These findings suggest a notable willingness among pregnant women to undergo NIPT. Additionally, the results suggest that various factors, including place of residence, educational level, family income, causes of abortion, and conception method, influence pregnant women's knowledge about NIPT Accordingly, the level of NIPT knowledge varies among pregnant women.

Conclusion

The survey generally revealed that pregnant women were strongly inclined to select NIPT; however, expectant Chinese mothers possess limited knowledge and perception regarding this screening method for fetal aneuploidy. Therefore, the government must implement effective measures to augment public awareness of fetal aneuploidy screening and encourage the judicious utilization of NIPT.

Incidence of sex chromosome aneuploidy in a prenatal population: 27-year longitudinal study in Northern Italy

OBJECTIVES

The availability of cell-free (cf) DNA as a prenatal screening tool affords an opportunity for non-invasive identification of sex chromosome aneuploidy (SCA). The aims of this longitudinal study were to investigate the evolution and frequency of both invasive prenatal diagnostic testing, using amniocentesis and chorionic villus sampling (CVS), and the detection of SCA in cfDNA samples from a large unselected cohort in Northern Italy.

METHODS

The results of genetic testing from CVS and amniotic fluid samples received from public and private centers in Italy from 1995 to 2021 were collected. Chromosomal analysis was performed by routine Q-banding karyotype. Regression analyses and descriptive statistics were used to determine population data trends regarding the frequency of prenatal diagnostic testing and the identification of SCA, and these were compared with the changes in indication for prenatal diagnostic tests and available screening options.

RESULTS

Over a period of 27 years, there were 13 939 526 recorded births and 231 227 invasive procedures were performed, resulting in the prenatal diagnosis of 933 SCAs. After the commercial introduction of cfDNA use in 2015, the frequency of invasive procedures decreased significantly (P = 0.03), while the frequency of prenatal SCA detection increased significantly (P = 0.007). Between 2016 and 2021, a high-risk cfDNA result was the indication for 31.4% of detected sex chromosome trisomies, second only to advanced maternal age.

CONCLUSIONS

Our findings suggest that the inclusion of SCA in prenatal cfDNA screening tests can increase the prenatal diagnosis of affected individuals. As the benefits of early ascertainment are increasingly recognized, it is essential that healthcare providers are equipped with comprehensive and evidence-based information regarding the associated phenotypic differences and the availability of targeted effective interventions to improve neurodevelopmental and health outcomes for affected individuals. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

A Novel Paradigm for Non-Invasive Prenatal Genetic Screening: Trophoblast Retrieval and Isolation from the Cervix (TRIC)

As the prevalence of pregnancies with advanced maternal age increases, the risk of fetal chromosomal abnormalities is on the rise. Therefore, prenatal genetic screening and diagnosis have become essential elements in contemporary obstetrical care. Trophoblast retrieval and isolation from the cervix (TRIC) is a non-invasive procedure that can be utilized for prenatal genetic diagnosis. The method involves the isolation of fetal cells (extravillous trophoblasts) by transcervical sampling; along with its non-invasiveness, TRIC exhibits many other advantages such as its usefulness in early pregnancy at 5 weeks of gestation, and no interference by various fetal and maternal factors. Moreover, the trophoblast yields from TRIC can provide valuable information about obstetrical complications related to abnormal placentation even before clinical symptoms arise. The standardization of this clinical tool is still under investigation, and the upcoming advancements in TRIC are expected to meet the increasing need for a safe and accurate option for prenatal diagnosis.

Investigating the "Fetal Side" in Recurrent Pregnancy Loss: Reliability of Cell-Free DNA Testing in Detecting Chromosomal Abnormalities of Miscarriage Tissue

(1) Background: The aim of our study is to evaluate whether cell-free DNA testing can overlap the genetic testing of miscarriage tissue in women with early pregnancy loss (EPL) and length of recurrent pregnancy loss (RPL); (2) Methods: We conducted a prospective cohort study at the Pregnancy Loss Unit of the Fondazione Policlinico Universitario A. Gemelli (IRCCS), Rome, Italy between May 2021 and March 2022. We included women with EPL and length of RPL. Gestational age was >9 weeks + 2 days and <12 weeks + 0 days of gestation corresponding to a crown rump length measurement of >25 and <54 mm. Women underwent both dilation and curettage for the collection of miscarriage tissue and for blood sample collection. Chromosomal microarray analysis (CMA) on miscarriage tissues was performed by oligo-nucleotide- and single nucleotide polymorphisms (SNP)-based comparative genomic hybridization (CGH+SNP). Maternal blood samples were analyzed by Illumina VeriSeq non-invasive prenatal testing (NIPT) to evaluate the cell-free fetal DNA (cfDNA) and the corresponding fetal fraction and the presence of genetic abnormalities; (3) Results: CMA on miscarriage tissues revealed chromosome aneuploidies in 6/10 cases (60%), consisting of trisomy 21 (5 cases) and monosomy X (one case). cfDNA analysis was able to identify all cases of trisomy 21. It failed to detect monosomy X. A large 7p14.1p12.2 deletion concomitant to trisomy 21 was, in one case, detected by cfDNA analysis but it was not confirmed by CMA on miscarriage tissue. (4) Conclusions: cfDNA largely reproduces the chromosomal abnormalities underlying spontaneous miscarriages. However, diagnostic sensitivity of cfDNA analysis is lower with respect to the CMA of miscarriage tissues. In considering the limitations when obtaining biological samples from aborted fetuses suitable for CMA or standard chromosome analysis, cfDNA analysis is a useful, although not exhaustive, tool for the chromosome diagnosis of both early and recurrent pregnancy loss.

Clinical Experience with Genome-Wide Noninvasive Prenatal Screening in a Large Cohort of Twin Pregnancies

Non-invasive prenatal screening (NIPS) in twin gestations has been shown to have high detection rates and low false-positive rates for trisomy 21, as seen in singleton pregnancies, although there have been few large cohort twin studies, genome-wide studies in particular, to date. In this study, we looked at the performance of genome-wide NIPT in a large cohort consisting of 1244 twin pregnancy samples collected over a two-year period in a single laboratory in Italy. All samples underwent an NIPS for common trisomies, with 61.5% of study participants choosing to undergo genome-wide NIPS for additional fetal anomalies (namely, rare autosomal aneuploidies and CNVs). There were nine initial no-call results, all of which were resolved upon retest. Based on our NIPS results, 17 samples were at high risk for trisomy 21, one for trisomy 18, six for a rare autosomal aneuploidy, and four for a CNV. Clinical follow-up was available for 27 out of 29 high-risk cases; a sensitivity of 100%, a specificity of 99.9%, and a PPV of 94.4% were noted for trisomy 21. Clinical follow-up was also available for 1110 (96.6%) of the low-risk cases, all of which were true negatives. In conclusion, we found that NIPS was a reliable screening approach for trisomy 21 in twin pregnancies.

Non-Invasive prenatal testing with rolling circle amplification: Real-world clinical experience in a non-molecular laboratory

BACKGROUND

Non-invasive prenatal testing (NIPT) using cell-free DNA (cfDNA) circulating in maternal blood provides a sensitive and specific screening technique for common fetal aneuploidies, but the high cost and workflow complexity of conventional methodologies limit its widespread implementation. A unique rolling circle amplification methodology reduces cost and complexity, providing a promising alternative for increased global accessibility as a first-tier test.

METHODS

In this clinical study, 8160 pregnant women were screened on the Vanadis system for trisomies 13, 18, and 21, and positive results were compared to clinical outcomes where available.

RESULTS

The Vanadis system yielded a 0.07% no-call rate, a 98% overall sensitivity, and a specificity of over 99% based on available outcomes.

CONCLUSION

The Vanadis system provided a sensitive, specific, and cost-effective cfDNA assay for trisomies 13, 18, and 21, with good performance characteristics and low no-call rate, and it eliminated the need for either next-generation sequencing or polymerase chain reaction amplification.

A Case Report of a Feto-Placental Mosaicism Involving a Segmental Aneuploidy: A Challenge for Genome Wide Screening by Non-Invasive Prenatal Testing of Cell-Free DNA in Maternal Plasma

Non-invasive prenatal testing (NIPT) using cell-free DNA can detect fetal chromosomal anomalies with high clinical sensitivity and specificity. In approximately 0.1% of clinical cases, the NIPT result and a subsequent diagnostic karyotype are discordant. Here we report a case of a 32-year-old pregnant patient with a 44.1 Mb duplication on the short arm of chromosome 4 detected by NIPT at 12 weeks' gestation. Amniocentesis was carried out at 18 weeks' gestation, followed by conventional and molecular cytogenetic analysis on cells from the amniotic fluid. SNP array analysis found a de novo deletion of 1.2 Mb at chromosome 4, and this deletion was found to be near the critical region of the Wolf-Hirschhorn syndrome. A normal 46,XY karyotype was identified by G-banding analysis. The patient underwent an elective termination and molecular investigations on tissues from the fetus, and the placenta confirmed the presence of type VI true fetal mosaicism. It is important that a patient receives counselling following a high-risk call on NIPT, with appropriate diagnostic analysis advised before any decisions regarding the pregnancy are taken. This case highlights the importance of genetic counselling following a high-risk call on NIPT, especially in light of the increasing capabilities of NIPT detection of sub-chromosomal deletions and duplications.

Haplotype-based non-invasive prenatal diagnosis of recessive dystrophic epidermolysis bullosa via targeted capture sequencing of maternal plasma

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare and severe hereditary skin disease, caused by mutations in the COL7A1. However, whether non-invasive prenatal testing (NIPT) can be used for this monogenic genodermatosis remains unknown. Accordingly, we conducted a study in which one couple at high risk of having a fetus with RDEB were recruited and tested by haplotyping-based NIPT. Next-generation sequencing-based multi-gene panel testing was carried out in this couple and their first child as proband who was affected with RDEB. We deduced parental haplotypes via single nucleotide polymorphism (SNP)-based haplotype linkage analysis. Then the maternal plasma cell-free DNA was also sequenced to determine the fetal haplotypes using a parental haplotype-assisted hidden Markov model (HMM) analysis. Results show that the fetus was only a heterozygous mutation carrier in COL7A1 and the identical results were obtained after birth. These results demonstrate that haplotyping-based NIPT is a feasible method for NIPT of RDEB.

Factors related to indecisive attitudes toward non-invasive prenatal testing among women of reproductive age in Japan

AIM

This study aimed to investigate the factors related to indecisive attitudes toward noninvasive prenatal testing (NIPT) among nonpregnant women of reproductive age.

METHODS

We conducted an online survey involving nonpregnant Japanese women aged 20-49 years. The questionnaires consisted of a hypothetical question about whether they would decide to undergo NIPT if they were to become pregnant, and responses with "unsure" were defined as indecisive attitudes.

RESULTS

Of 1250 participants, 412 (33%) held indecisive attitudes on whether to undergo NIPT. Multivariable logistic regression analysis demonstrated indecisive attitudes were related to a low level of knowledge about prenatal testing (adjusted odds ratio [AOR] 3.89) and preferences for family-driven decisions (AOR 1.44) instead of provider-driven.

CONCLUSION

Even though the NIPT is widespread, many nonpregnant women of reproductive age are unable to decide whether to undergo the NIPT or not. Hence, indecisive women toward NIPT require adequate information and communication about future NIPT among their families prior to conception. Therefore, preconception support of providing adequate information about testing and facilitating communication regarding future NIPT among women and their family members may help indecisive women make autonomous decisions on NIPT.

Experiences of receiving an increased chance of sex chromosome aneuploidy result from non-invasive prenatal testing in Australia: "A more complicated scenario than what I had ever realized"

Many non-invasive prenatal testing (NIPT) platforms screen for sex chromosome aneuploidy (SCA) and SCA analysis is generally included in Australia where NIPT is available as a self-funded test. Little is known about the experience of receiving an NIPT result indicating an increased chance of SCA. This study aimed to explore the experiences of people who received this result and their perspectives on the information, care, and support they received from healthcare practitioners (HCPs). Semi-structured interviews were conducted with people who received an NIPT result indicating an increased chance of SCA and continued their pregnancy. Most participants only had contact with a genetic counselor after receiving their result. Transcribed data were analyzed using rigorous thematic analysis to identify important patterns and themes. Participants (18 women, 2 male partners) described embarking on NIPT, primarily based on advice from their HCP and without much consideration. Consequently, participants expressed feeling unprepared for the unanticipated complexity of their NIPT result and were faced with making a time-sensitive decision about a condition they had not previously considered. While more pre-test information was desired, timely access to genetic counseling post-test assisted with adjustment to the result. These findings suggest that routinization of NIPT may be compromising informed decision-making, resulting in unpreparedness for an increased chance result. Given the increasing uptake and expanding scope of NIPT, resources should be dedicated to educating HCPs offering NIPT and ensuring timely access to genetic counseling post-result. With appropriate funding, genetics services may be able to play a central role in offering information and support to both people who undertake NIPT and their HCPs ordering the testing. Implementing a publicly funded screening program in Australia could assist with standardizing prenatal screening care pathways and consequently better access to appropriate resources.

Accuracy of Non-Invasive Prenatal Testing for Duchenne Muscular Dystrophy in Families at Risk: A Systematic Review

BACKGROUND

Methodological advancements, such as relative haplotype and relative mutation dosage analyses, have enabled non-invasive prenatal diagnosis of autosomal recessive and X-linked diseases. Duchenne muscular dystrophy (DMD) is an X-linked recessive disease characterized by progressive proximal muscular dystrophy and a high mortality rate before the age of twenty. We aimed to systematically present obtainable data regarding a non-invasive prenatal diagnosis of DMD and provide a comprehensive resume on the topic. The emphasis was given to the comparison of different available protocols and molecular methods used for fetal inheritance deduction, as well as their correlation with prognostic accuracy.

METHODS

We searched the Scopus and PubMed databases on 11 November 2022 and included articles reporting a non-invasive prenatal diagnosis of DMD in families at risk using relative dosage analysis methods.

RESULTS

Of the 342 articles identified, 7 met the criteria. The reported accuracy of NIPT for DMD was 100% in all of the studies except one, which demonstrated an accuracy of 86.67%. The combined accuracy for studies applying indirect RHDO, direct RHDO, and RMD approaches were 94.74%, 100%, and 100%, respectively. Confirmatory results by invasive testing were available in all the cases. Regardless of the technological complexity and low prevalence of the disease that reduces the opportunity for systematic research, the presented work demonstrates substantial accuracy of NIPT for DMD.

CONCLUSIONS

Attempts for its implementation into everyday clinical practice raise many ethical and social concerns. It is essential to provide detailed guidelines and arrange genetic counseling in order to ensure the proper indications for testing and obtain informed parental consent.

Inconsistency between non-invasive prenatal testing (NIPT) and conventional prenatal diagnosis due to confined placental and fetal mosaicism: Two case reports

We aimed to identify the causes of inconsistent results between non-invasive prenatal testing (NIPT) and invasive testing methods for trisomy 21. In the first case, NIPT was performed at 11 weeks of pregnancy, and the result showed a high risk of trisomy 21 [fetal fraction (FF) = 6.98%, 21 chromosome Z-score = 3.6]. The patient underwent quantitative fluorescent (QF)-PCR and karyotyping at 14 + 0 weeks of pregnancy through CVS showing mosaicism of 47, XX, + 21[11] and 46, XX [39] in karyotyping. The patient underwent amniocentesis at 15 + 6 weeks, showing a normal pattern in QF-PCR and 46, XX karyotyping in long term culture. The second case underwent NIPT at 16 + 5 weeks of pregnancy (FF = 7.52%, 21 chromosome Z-score = 2.503). She underwent an invasive test at 19 weeks through amniotic fluid sampling. As a result, trisomy 21 was detected by QF-PCR, and mosaicism of XX, +21[22]/46, XX [4] was identified by karyotyping. Despite significant advances in fetal chromosome analysis using NIPT, invasive testing is still needed as placenta-derived DNA does not reflect 100% fetal genetic information. Placental mosaicism can be detected by NIPT, but more research is needed to increase its sensitivity. Therefore, if the NIPT result is positive, an invasive test can confirm the result, and continuous monitoring is required even if the NIPT result is negative.

Clinician views and experiences of non-invasive prenatal genetic screening tests in Australia

BACKGROUND

Non-invasive prenatal screening (NIPS) is being increasingly used by expectant parents. Much provision of this test in Australia is occurring in clinical settings where specialised genetic counselling is unavailable, such as general practice. Potential psychosocial consequences from this kind of prenatal genetic screening remain largely unexplored.

AIMS

To explore clinicians' experiences with NIPS for aneuploidy, their perspectives of the benefits and harms of NIPS, clinicians' information needs, and their perceptions of the needs of expectant parents.

MATERIALS AND METHODS

Qualitative, semi-structured interviews with 17 health professionals (clinical geneticists, obstetricians, genetic counsellors and general practitioners) who request and counsel for NIPS in Australian hospital and private practice settings, conducted between June 2019 and February 2020.

RESULTS

Five themes were identified relating to clinicians' perceptions and experiences of NIPS in their practice: perceived benefits of NIPS, perceived harms of NIPS (with two subthemes: clinical harms and psychosocial harms), financial and equity-related concerns, counselling as a protective buffer against perceived harms, and clinicians' unmet education needs. While clinicians view NIPS as a useful and high-quality screening test, especially for detection of common trisomies, many participants had concerns about how NIPS has been implemented in practice, particularly the quality (and often absence) of pre-/post-test counselling and the routinisation of testing for sex chromosome aneuploidies, microdeletion and microduplication syndromes.

CONCLUSION

These findings support the need for targeted clinician training around NIPS, and for a shared decision-making approach to support expectant parents' autonomous decisions about NIPS.

Combined Model-Based Prediction for Non-Invasive Prenatal Screening

The risk of chromosomal abnormalities in the child increases with increasing maternal age. Although non-invasive prenatal testing (NIPT) is a safe and effective prenatal screening method, the accuracy of the test results needs to be improved owing to various testing conditions. We attempted to achieve a more accurate and robust prediction of chromosomal abnormalities by combining multiple methods. Here, three different methods, namely standard Z-score, normalized chromosome value, and within-sample reference bin, were used for 1698 reference and 109 test samples of whole-genome sequencing. The logistic regression model combining the three methods achieved a higher accuracy than any single method. In conclusion, the proposed method offers a promising approach for increasing the reliability of NIPT.

Does a High-Risk (>1/50) Result for First-Trimester Combined Screening Always Entail Invasive Testing? Which Patients from This Group Might Benefit from cfDNA Testing?

Currently, cell-free DNA (cfDNA) is offered as part of a contingent screening for patients with a first-trimester combined test (FCT) risk between 1/50 and 1/250. However, most aneuploidies are within the group of patients with a risk above 1/10. An observational, retrospective, and multi-centric study was carried out, to evaluate the theorical performance of lowering the cut-off point for the high-risk group from 1/50 to 1/10. Out of the 25,920 patients included, 25,374 (97.9%) consented to the cfDNA contingent screening for aneuploidies. With the proposed strategy, knowing that the detection rate (DR) of cfDNA testing for trisomy 21 is 99.7%, the DR for trisomy 21 would have stayed in a 93.2%, just as it was with the current strategy. In this instance, 267 (1.1%) invasive tests would have been performed, while the current strategy had a total of 307 (1.2%). The false positive rate (FPR) rate would have stayed at 5.2% in both scenarios. In conclusion, the contingent screening of aneuploidies based in the result of the FCT, offering the analysis of cfDNA to patients with an intermediate risk after lowering the cut-off point from 1/50 to 1/10, is a valid alternative that might maintain the current detection rates and avoid the complications associated with invasive testing.

Validity and Utility of Non-Invasive Prenatal Testing for Copy Number Variations and Microdeletions: A Systematic Review

Valid data on prenatal cell-free DNA-based screening tests for copy number variations and microdeletions are still insufficient. We aimed to compare different methodological approaches concerning the achieved diagnostic accuracy measurements and positive predictive values. For this systematic review, we searched the Scopus and PubMed databases and backward citations for studies published between 2013 and 4 February 2022 and included articles reporting the analytical and clinical performance of cfDNA screening tests for CNVs and microdeletions. Of the 1810 articles identified, 32 met the criteria. The reported sensitivity of the applied tests ranged from 20% to 100%, the specificity from 81.62% to 100%, and the PPV from 3% to 100% for cases with diagnostic or clinical follow-up information. No confirmatory analysis was available in the majority of cases with negative screening results, and, therefore, the NPVs could not be determined. NIPT for CNVs and microdeletions should be used with caution and any developments regarding new technologies should undergo strict evaluation before their implementation into clinical practice. Indications for testing should be in correlation with the application guidelines issued by international organizations in the field of prenatal diagnostics.

Controversies in implementing non-invasive prenatal testing in a public antenatal care program

Women's autonomy and an inclusive society for all individuals are highly valued in Norway. The Norwegian Biotechnology Act changed in 2020 allowing first-trimester screening and cell-free DNA for common trisomies to all pregnant women. However, implementing non-invasive prenatal testing (NIPT) in a public antenatal care program is difficult, because many patients, politicians, and medical professionals do not consider trisomy 21 a severe medical disease. Screening for trisomies at an early gestation might inevitably lead to an increase in pregnancy terminations and making cost-benefit calculations is ethically challenging. Moreover, offering NIPT to all pregnant women is debatable because of the lower prevalence of fetal trisomies in younger women. Therefore, appropriate genetic pre-test counseling is essential. Furthermore, organizing the service between private institutions and public hospitals poses another debate and challenges both quality and equal access to health services for women across the country.

Simulated confined placental mosaicism proportion (SCPMP) based on cell-free fetal DNA fraction enrichment can reduce false-positive results in non-invasive prenatal testing

OBJECTIVE

To decrease the false-positive rate of NIPT using cell-free fetal DNA (cffDNA) fraction enrichment and the simulated confined placental mosaicism proportion (SCPMP) threshold application via cffDNA quantification.

METHOD

Using a cffDNA enrichment method, 303 plasma samples with positive NIPT results (Z-score > 3.0; 200 true-positive and 103 false-positive cases) were re-sequenced. A method to calculate the SCPMP based on the quantified cffDNA fraction was developed; the SCPMP threshold between true- and false-positive NIPT results was determined and used for re-analyses.

RESULTS

With enrichment, the fetal fraction of the 303 samples was 26.9 ± 8.4%, compared to 11.0 ± 3.2% without enrichment. The optimized threshold method with double determination using the Z-value-defined SCPMP can reduce the false-positive rates for trisomies 21, 18, and 13 by 87%, 80%, and 88.9%, respectively.

CONCLUSION

Our optimized method can decrease the false-positive rate of NIPT results. This article is protected by copyright. All rights reserved.

Confirmed non-invasive prenatal testing for foetal Rh blood group genotyping along with bi-allelic short insertion/deletion polymorphisms as a positive internal control

BACKGROUND

Determination of foetus rhesus blood group at risk of hemolytic disease has potential application for early non-invasive prenatal testing (NIPT). There are several challenges in developing NIPT rhesus blood group genotyping assays by using cell-free foetal DNA (cff-DNA) in plasma of RhD-negative pregnant women. So, the aim of this study was optimization of Real-time PCR assay for NIPT rhesus genotyping and development of Bi-allelic short insertion/deletion polymorphisms (INDELs) as internal control to optimise and validate rhesus genotyping based on Real-time PCR to avoid false or negative results.

MATERIAL AND METHODS

NIPT Rhesus genotyping including RHD (exon 7), RHCc, and RHEe genes were performed by TaqMan Real-time PCR on 104 maternal samples at different gestation ages (12 to ≥40 weeks) from 51 alloimmunized pregnant women. The sensitivity protocol was confirmed with standard DNA samples. Eight selected INDELs were designed and used to detectable cff-DNA in maternal plasma. INDELs frequency and inheritance were determined on 6 family and 61 unrelated individuals. Finally, multiplex Real-time PCR was performed for each sample with INDELs pairs and Rh probes.

RESULTS

The results showed 100% accuracy rhesus typing for RHD, RHC and RHE assays and 95.7% accuracy for RHc. Also, eight selected INDELs as internal control for NIPT were 100% concordance for typed samples.

CONCLUSION

The Real-time PCR assay is a suitable method with high sensitivity and specificity for rhesus typing as NIPT for prediction of hemolytic disease in foetuses. The INDELs described here are suitable internal control for confirmation of NIPT on cff-DNA.

Lipid Metabolism Affects Fetal Fraction and Screen Failures in Non-invasive Prenatal Testing

Objective: To assess the association between lipid metabolism and fetal fraction, which is a critical factor in ensuring a highly accurate non-invasive prenatal testing (NIPT), and on the rate of screen failures or “no calls” in NIPT.

Methods: A total of 4,514 pregnant women at 12–26 weeks of gestation underwent NIPT sequencing and serum lipid measurements. Univariate analysis and multivariate regression models were used to evaluate the associations of serum lipid concentrations with the fetal fraction and the rate of screen failures.

Results: The fetal fraction decreased with increased low-density lipoprotein cholesterol and triglyceride (TG) levels, which were significant factors (standardized coefficient: −0.11). Conversely, high-density lipoprotein cholesterol and the interval between the two tests were positively correlated with the fetal fraction. The median fetal fraction was 10.88% (interquartile range, 8.28–13.89%) and this decreased with TG from 11.56% at ≤1.10 mmol/L to 9.51% at >2.30 mmol/L. Meanwhile, multivariate logistic regression analysis revealed that increased TG levels were independently associated with the risk of screen failures. The rate of screen failures showed an increase with TG levels from 1.20% at ≤1.70 mmol/L to 2.41% at >2.30 mmol/L.

Conclusions: The fetal fraction and the rate of screen failures in NIPT are affected by TG levels. Meanwhile, in pregnant women with high TG levels, delaying the time between NIPT blood collections can significantly increase the fetal fraction.

Is Cell-free fetal DNA testing a safe option for women in a high-risk population after combined first-trimester testing?

OBJECTIVES

Our study aimed to examine the relevance of cell-free fetal DNA (cfDNA) testing on the screening of chromosomal defects and the issue of pregnancies in patients with a risk over 1:50 after the first-trimester combined test.

METHODS

This is a retrospective monocentric study. We included all consecutive patients with a singleton pregnancy between January 2015 and December 2020 attending our fetal medicine centre because the estimated risk for trisomy 21 after the first-trimester combined screening was over 1:50. The patients could either choose to have invasive testing or cell-free DNA testing. We collected data about the patient, the tests results (cfDNA, karyotype) and the pregnancy outcome (born alive, medical termination, miscarriage or intrauterine fetal death).

RESULTS

We included 98 patients with an estimated risk for trisomy 21 over 1:50. We found a total of 14 major chromosomal abnormalities (14/98; 14.3%), of which: thirteen trisomies 21 and one triploidy 69, XXY. A cfDNA testing was chosen by 34 (34/98; 34.7%) patients. Among the pathological results of invasive testing, 5 (5/64; 7.8%) couldn't be targeted by cfDNA testing. Two of them were placental mosaicism, one a triploidy 69, XXY, and two defects inherited from a parent and considered benign. There was no miscarriage linked to an invasive test in the population study.

CONCLUSION

In our monocentric cohort, a third of the patients choose cfDNA in a case of a risk over 1:50 after combined testing. Even if this cohort is too small to draw definitive conclusions, cfDNA could be safe in a high-risk population after combined testing. None of the chromosomal abnormalities found at the karyotype and non-detectable by cfDNA was a loss of information that impacted pregnancy follow-up. Further study could explore the input of Genome-Wide cfDNA and chromosomal micro-array in this population.

Initial Clinical Experience with NIPT for Rare Autosomal Aneuploidies and Large Copy Number Variations

OBJECTIVE

Amniocentesis, chorionic villi sampling and first trimester combined testing are able to screen for common trisomies 13, 18, and 21 and other atypical chromosomal anomalies (ACA). The most frequent atypical aberrations reported are rare autosomal aneuploidies (RAA) and copy number variations (CNV), which are deletions or duplications of various sizes. We evaluated the clinical outcome of non-invasive prenatal testing (NIPT) results positive for RAA and large CNVs to determine the clinical significance of these abnormal results.

METHODS

Genome-wide NIPT was performed on 3664 eligible patient samples at a single genetics center. For patients with positive NIPT reports, the prescribing physician was asked retrospectively to provide clinical follow-up information using a standardized questionnaire.

RESULTS

RAAs and CNVs (>7 Mb) were detected in 0.5%, and 0.2% of tested cases, respectively. Follow up on pregnancies with an NIPT-positive result for RAA revealed signs of placental insufficiency or intra-uterine death in 50% of the cases and normal outcome at the time of birth in the other 50% of cases. We showed that CNV testing by NIPT allows for the detection of unbalanced translocations and relevant maternal health conditions.

CONCLUSION

NIPT for aneuploidies of all autosomes and large CNVs of at least 7 Mb has a low "non-reportable"-rate (<0.2%) and allows the detection of additional conditions of clinical significance.

Genetic Counseling and Management: The First Study to Report NIPT Findings in a Romanian Population

Background and Objectives: Non-invasive prenatal testing (NIPT) has been confirmed as the most accurate screening test for trisomies 21, 18, 13, sex chromosomes aneuploidies and several microdeletions. This study aimed to assess the accuracy of cell free DNA testing based on low-level whole-genome sequencing to screen for these chromosomal abnormalities and to evaluate the clinical performance of NIPT. Materials and Methods: 380 consecutive cases from a single genetic center, from Western Romania were included in this retrospective study. Cell-free nucleic acid extraction from maternal blood, DNA sequencing and analysis of sequenced regions were performed by BGI Hong Kong and Invitae USA to determine the risk of specific fetal chromosomal abnormalities. In high-risk cases the results were checked by direct analysis of fetal cells obtained by invasive methods: 6 chorionic villus sampling and 10 amniocenteses followed by combinations of QF-PCR, karyotyping and aCGH. Results: NIPT results indicated low risk in 95.76% of cases and high risk in 4.23%. Seven aneuploidies and one microdeletion were confirmed, the other results were found to be a false-positive. A gestational age of up to 22 weeks had no influence on fetal fraction. There were no significant differences in fetal fraction across the high and low risk groups. Conclusions: This is the first study in Romania to report the NIPT results. The confirmation rate was higher for autosomal aneuploidies compared to sex chromosome aneuploidies and microdeletions. All cases at risk for trisomy 21 were confirmed. Only one large fetal microdeletion detected by NIPT has been confirmed. False positive NIPT results, not confirmed by invasive methods, led to the decision to continue the pregnancy. The main limitation of the study is the small number of patients included. NIPT can be used as a screening method for all pregnancies, but in high-risk cases, an invasive confirmation test was performed.

Clinical experience with non-invasive prenatal screening for single-gene disorders

OBJECTIVE

To assess the performance of a non-invasive prenatal screening test (NIPT) for a panel of dominant single-gene disorders (SGD) with a combined population incidence of 1 in 600.

METHODS

Cell-free fetal DNA isolated from maternal plasma samples accessioned from 14 April 2017 to 27 November 2019 was analyzed by next-generation sequencing, targeting 30 genes, to look for pathogenic or likely pathogenic variants implicated in 25 dominant conditions. The conditions included Noonan spectrum disorders, skeletal disorders, craniosynostosis syndromes, Cornelia de Lange syndrome, Alagille syndrome, tuberous sclerosis, epileptic encephalopathy, SYNGAP1-related intellectual disability, CHARGE syndrome, Sotos syndrome and Rett syndrome. NIPT-SGD was made available as a clinical service to women with a singleton pregnancy at ≥ 9 weeks' gestation, with testing on maternal and paternal genomic DNA to assist in interpretation. A minimum of 4.5% fetal fraction was required for test interpretation. Variants identified in the mother were deemed inconclusive with respect to fetal carrier status. Confirmatory prenatal or postnatal diagnostic testing was recommended for all screen-positive patients and follow-up information was requested. The screen-positive rates with respect to the clinical indication for testing were evaluated.

RESULTS

A NIPT-SGD result was available for 2208 women, of which 125 (5.7%) were positive. Elevated test-positive rates were observed for referrals with a family history of a disorder on the panel (20/132 (15.2%)) or a primary indication of fetal long-bone abnormality (60/178 (33.7%)), fetal craniofacial abnormality (6/21 (28.6%)), fetal lymphatic abnormality (20/150 (13.3%)) or major fetal cardiac defect (4/31 (12.9%)). For paternal age ≥ 40 years as a sole risk factor, the test-positive rate was 2/912 (0.2%). Of the 125 positive cases, follow-up information was available for 67 (53.6%), with none classified as false-positive. No false-negative cases were identified.

CONCLUSIONS

NIPT can assist in the early detection of a set of SGD, particularly when either abnormal ultrasound findings or a family history is present. Additional clinical studies are needed to evaluate the optimal design of the gene panel, define target populations and assess patient acceptability. NIPT-SGD offers a safe and early prenatal screening option. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

WisecondorFF: Improved Fetal Aneuploidy Detection from Shallow WGS through Fragment Length Analysis

In prenatal diagnostics, NIPT screening utilizing read coverage-based profiles obtained from shallow WGS data is routinely used to detect fetal CNVs. From this same data, fragment size distributions of fetal and maternal DNA fragments can be derived, which are known to be different, and often used to infer fetal fractions. We argue that the fragment size has the potential to aid in the detection of CNVs. By integrating, in parallel, fragment size and read coverage in a within-sample normalization approach, it is possible to construct a reference set encompassing both data types. This reference then allows the detection of CNVs within queried samples, utilizing both data sources. We present a new methodology, WisecondorFF, which improves sensitivity, while maintaining specificity, relative to existing approaches. WisecondorFF increases robustness of detected CNVs, and can reliably detect even at lower fetal fractions (<2%).

Do non-invasive prenatal tests promote discrimination against people with Down syndrome? What should be done?

By implementation of non-invasive prenatal testing (NIPT) for the diagnosis of Down syndrome (DS) in maternity care, an ethical debate is newly inflamed how to deal with this information. Fears of the consequences of an increased use of NIPT are justified with the same arguments when amniocentesis and preimplantation genetic diagnosis (PGD) were introduced decades ago. It can be expected that the prevalence of people with DS would significantly increase in Western societies as a result of the increasing age of pregnant women and the improved medical care for people with DS. The net effect as to whether an increasing uptake of NIPT will result in more abortions of fetuses with trisomy 21 cannot be reliably estimated. This holds true since more and more couples will use results of NIPT for information only, but will not opt for termination of pregnancy. Although parents love their children with DS, in a society where reproductive autonomy is seen as an achievement, access to NIPT cannot be limited. On this background, comprehensive and qualified pretest counseling is vital, also to avoid possible stigmatization of people with DS and as the resulting consequence to avoid feared deterioration in their living conditions, for which, however, there is no evidence to date. The personal view of a mother of a child with DS illustrates the complexity in dealing with NIPT, which does not allow simple answers and must be understood as a challenge for society as a whole.

Liquid biopsy: state of reproductive medicine and beyond

Liquid biopsy is the process of sampling and analyzing body fluids, which enables non-invasive monitoring of complex biological systems in vivo. Liquid biopsy has myriad applications in health and disease as a wide variety of components, ranging from circulating cells to cell-free nucleic acid molecules, can be analyzed. Here, we review different components of liquid biopsy, survey state-of-the-art, non-invasive methods for detecting those components, demonstrate their clinical applications and discuss ethical considerations. Furthermore, we emphasize the importance of artificial intelligence in analyzing liquid biopsy data with the aim of developing ethically-responsible non-invasive technologies that can enhance individualized healthcare. While previous reviews have mainly focused on cancer, this review primarily highlights applications of liquid biopsy in reproductive medicine.

Integrity of cell-free DNA in maternal plasma extracellular vesicles as a potential biomarker for non-invasive prenatal testing

OBJECTIVE

Large proportions of cell-free DNA (cfDNA) in plasma are localized in extracellular vesicles (EVs), which are secreted from placental cells. This study was conducted to reveal the integrity pattern of cfDNA in maternal plasma EVs (evcfDI) across gestation, and explore if evcfDI could be a potential biomarker in screening for aneuploid fetus in non-invasive prenatal testing (NIPT).

METHODS

A total of 180 maternal plasma samples were collected during NIPT. Both evcfDNA and fetal evcfDNA (evcffDNA) were measured by quantitative PCR of LINE1 and SRY gene amplicons with different sizes. The evcfDI was calculated as the ratio of long to short fragments.

RESULTS

evcfDI is not affected by gestational age; whereas evcffDI has a mild decreasing trend with increasing gestational age (P = 0.048). evcfDI is significantly and negatively correlated with maternal body mass index (BMI; calculated as weight in kilograms divided by the square of height in meters: ≤18.5, 18.5-25, and ≥25) (P < 0.01) and age (<35 and ≥35 years) (P < 0.01). Mean evcfDI decreases from 2.113 in euploid controls to 0.681 in those with an aneuploid fetus in NIPT (P = 0.003).

CONCLUSION

Maternal clinical characteristics such as BMI and age could be innovative biomarkers to calibrate evcfDI, which was shown to be a potential indicator of an aneuploid fetus. Analysis of evcfDI based on quantitative PCR could serve as a novel, rapid, and low-cost NIPT strategy, which might facilitate testing at earlier gestations.

Repurposing non-invasive prenatal testing data: Population study of single nucleotide variants associated with colorectal cancer and Lynch syndrome

In our previous work, genomic data generated through non-invasive prenatal testing (NIPT) based on low-coverage massively parallel whole-genome sequencing of total plasma DNA of pregnant women in Slovakia was described as a valuable source of population specific data. In the present study, these data were used to determine the population allele frequency of common risk variants located in genes associated with colorectal cancer (CRC) and Lynch syndrome (LS). Allele frequencies of identified variants were compared with six world populations to detect significant differences between populations. Finally, variants were interpreted, functional consequences were searched for and clinical significance of variants was investigated using publicly available databases. Although the present study did not identify any pathogenic variants associated with CRC or LS in the Slovak population using NIPT data, significant differences were observed in the allelic frequency of risk CRC variants previously reported in genome-wide association studies and common variants located in genes associated with LS. As Slovakia is one of the leading countries with the highest incidence of CRC among male patients in the world, there is a need for studies dedicated to investigating the cause of such a high incidence of CRC in Slovakia. The present study also assumed that extensive cross-country data aggregation of NIPT results would represent an unprecedented source of information concerning human genome variation in cancer research.

Screening for Fetal Aneuploidy and Sex Chromosomal Anomalies in a Pregnant Woman With Mosaicism for Turner Syndrome-Applications and Advantages of Cell-Based NIPT

Background: Cell-free NIPT and cell-based NIPT are risk-free testing options using maternal blood samples to screen for fetal aneuploidies, but the methods differ. For cell-free NIPT, the fetal fraction of cell-free DNA in plasma is analyzed with a high background of maternal DNA. In contrast, for cell-based NIPT, a limited number of the rare, intact fetal cells are isolated for the genetic analysis. This case demonstrates the differences regarding testing for fetal sex-chromosomes anomalies (SCAs) between these two tests. Materials and Methods: A pregnant woman with mosaicism for Turner syndrome opted for NIPT in first trimester. For the cell-free NIPT analysis, DNA extraction, genome-wide massive parallel sequencing, and data analysis were carried out as described by the kit manufacturer (Illumina©, San Diego, CA, USA). For cell-based NIPT, the first sample gave no result, but the woman consented to repeat cell-based NIPT. After whole genome amplification and STR analysis, fetal DNA from three individual fetal cells was subjected to chromosomal microarray (aCGH, Agilent oligoarray, 180 kb). Results: Fetal fraction was 7%, and cell-free NIPT showed 2 copies of chromosomes 13, 18, and 21 and a decreased proportion of chromosome X, suggestive of fetal Turner syndrome. In contrast, the cell-based NIPT result showed no aneuploidy and two X-chromosomes in the fetus. Conclusion: cell-based NIPT may provide a non-invasive testing option to screen for SCAs in women with mosaicism for monosomy-X in blood, where cell-free NIPT cannot discriminate whether the X-loss is maternal or fetal.

Experiences of non-invasive prenatal screening: A survey study

BACKGROUND

In Australia, using non-invasive prenatal testing (NIPT) to screen for fetal abnormalities is becoming more commonplace. However, there is a lack of standardised procedures surrounding pre-test counselling. This holds the potential for variability in pregnant people's experiences when undergoing NIPT, which subsequently may impact their ability to make informed decisions surrounding NIPT results.

AIM

This study sought to characterise the experiences of Australian women undergoing NIPT, including perceptions of informed choice, counselling experiences and decision to undergo NIPT.

MATERIALS AND METHODS

Australian women who had been recently pregnant (n = 94) completed an online survey which assessed: their knowledge of and attitude toward NIPT; satisfaction with counselling; satisfaction with their decision; and decisional conflict to undergo NIPT. The survey also allowed participants to provide qualitative information about their counselling experience and reasons for undergoing NIPT.

RESULTS

Overall, participants had good knowledge of and positive attitudes toward NIPT, experienced low decisional conflict and were overall satisfied with their counselling experience and decision to undergo NIPT. However, some participants expressed dissatisfaction with the lack of information provided, and biased language, by counselling providers. The desire to be informed was the most frequent reason for undergoing NIPT.

CONCLUSION

The provision of accurate and objective information in pre-test counselling is important to reduce decisional conflict and improve satisfaction with the decision to undergo NIPT. It is recommended counselling providers present pregnant people with neutral, objective, and accurate information at the time of pre-test counselling.

Cell-free DNA testing of maternal blood in screening for trisomies in twin pregnancy: updated cohort study at 10-14 weeks and meta-analysis

OBJECTIVE

To expand the limited knowledge on cell-free DNA (cfDNA) analysis of maternal blood for trisomies 21, 18 and 13 in twin pregnancy by updating the data from The Fetal Medicine Foundation (FMF) on prospective first-trimester screening and those identified in a systematic review of the literature.

METHODS

The FMF data were derived from prospective screening for trisomies 21, 18 and 13 in twin pregnancies at 10 + 0 to 14 + 1 weeks' gestation using the Harmony® prenatal test. A search of MEDLINE, EMBASE, CENTRAL (The Cochrane Library), ClinicalTrials.gov and the International Clinical Trials Registry Platform (World Health Organization) was carried out to identify all peer-reviewed publications on clinical validation or implementation of maternal cfDNA testing for trisomies 21, 18 and 13 in twin pregnancy, irrespective of gestational age at testing, in which data on pregnancy outcome were provided for at least 85% of the study population. Meta-analysis was performed using the FMF data and data from the studies identified by the literature search. This review was registered in the PROSPERO international database for systematic reviews RESULTS: In the FMF study, cfDNA testing was carried out in 1442 twin pregnancies and a result was obtained, after first or second sampling, in 1367 (94.8%) cases. In 93.1% (1272/1367) of cases, there was prenatal or postnatal karyotyping or birth of phenotypically normal babies; 95 cases were excluded from further analysis either because the pregnancy ended in termination, miscarriage or stillbirth with no known karyotype (n = 56) or there was loss to follow-up (n = 39). In the 1272 pregnancies included in the study, there were 20 cases with trisomy 21, 10 with trisomy 18, two with trisomy 13 and 1240 without trisomy 21, 18 or 13. The cfDNA test classified correctly 19 (95.0%) of the 20 cases of trisomy 21, nine (90.0%) of the 10 cases of trisomy 18, one (50.0%) of the two cases of trisomy 13 and 1235 (99.6%) of the 1240 cases without any of the three trisomies. The literature search identified 12 relevant studies, excluding our papers because their data are included in the current study. In the combined populations of our study and the 12 studies identified by the literature search, there were 137 trisomy-21 and 7507 non-trisomy-21 twin pregnancies; the pooled weighted detection rate (DR) and false-positive rate (FPR) were 99.0% (95% CI, 92.0-99.9%) and 0.02% (95% CI, 0.001-0.43%), respectively. In the combined total of 50 cases of trisomy 18 and 6840 non-trisomy-18 pregnancies, the pooled weighted DR and FPR were 92.8% (95% CI, 77.6-98.0%) and 0.01% (95% CI, 0.00-0.44%), respectively. In the combined total of 11 cases of trisomy 13 and 6290 non-trisomy-13 pregnancies, the pooled weighted DR and FPR were 94.7% (95% CI, 9.14-99.97%) and 0.10% (95% CI, 0.03-0.39%), respectively.

CONCLUSIONS

In twin pregnancy, the reported DR of trisomy 21 by cfDNA testing is high, but lower than that in singleton pregnancy, whereas the FPR appears to be equally low. The number of cases of trisomy 18 and more so trisomy 13 was too small for accurate assessment of the predictive performance of the cfDNA test. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

From late fatherhood to prenatal screening of monogenic disorders: evidence and ethical concerns

BACKGROUND

With the help of ART, an advanced parental age is not considered to be a serious obstacle for reproduction anymore. However, significant health risks for future offspring hide behind the success of reproductive medicine for the treatment of reduced fertility associated with late parenthood. Although an advanced maternal age is a well-known risk factor for poor reproductive outcomes, understanding the impact of an advanced paternal age on offspring is yet to be elucidated. De novo monogenic disorders (MDs) are highly associated with late fatherhood. MDs are one of the major sources of paediatric morbidity and mortality, causing significant socioeconomic and psychological burdens to society. Although individually rare, the combined prevalence of these disorders is as high as that of chromosomal aneuploidies, indicating the increasing need for prenatal screening. With the help of advanced reproductive technologies, families with late paternity have the option of non-invasive prenatal testing (NIPT) for multiple MDs (MD-NIPT), which has a sensitivity and specificity of almost 100%.

OBJECTIVE AND RATIONALE

The main aims of the current review were to examine the effect of late paternity on the origin and nature of MDs, to highlight the role of NIPT for the detection of a variety of paternal age-associated MDs, to describe clinical experiences and to reflect on the ethical concerns surrounding the topic of late paternity and MD-NIPT.

SEARCH METHODS

An extensive search of peer-reviewed publications (1980-2021) in English from the PubMed and Google Scholar databases was based on key words in different combinations: late paternity, paternal age, spermatogenesis, selfish spermatogonial selection, paternal age effect, de novo mutations (DNMs), MDs, NIPT, ethics of late fatherhood, prenatal testing and paternal rights.

OUTCOMES

An advanced paternal age provokes the accumulation of DNMs, which arise in continuously dividing germline cells. A subset of DNMs, owing to their effect on the rat sarcoma virus protein-mitogen-activated protein kinase signalling pathway, becomes beneficial for spermatogonia, causing selfish spermatogonial selection and outgrowth, and in some rare cases may lead to spermatocytic seminoma later in life. In the offspring, these selfish DNMs cause paternal age effect (PAE) disorders with a severe and even life-threatening phenotype. The increasing tendency for late paternity and the subsequent high risk of PAE disorders indicate an increased need for a safe and reliable detection procedure, such as MD-NIPT. The MD-NIPT approach has the capacity to provide safe screening for pregnancies at risk of PAE disorders and MDs, which constitute up to 20% of all pregnancies. The primary risks include pregnancies with a paternal age over 40 years, a previous history of an affected pregnancy/child, and/or congenital anomalies detected by routine ultrasonography. The implementation of NIPT-based screening would support the early diagnosis and management needed in cases of affected pregnancy. However, the benefits of MD-NIPT need to be balanced with the ethical challenges associated with the introduction of such an approach into routine clinical practice, namely concerns regarding reproductive autonomy, informed consent, potential disability discrimination, paternal rights and PAE-associated issues, equity and justice in accessing services, and counselling.

WIDER IMPLICATIONS

Considering the increasing parental age and risks of MDs, combined NIPT for chromosomal aneuploidies and microdeletion syndromes as well as tests for MDs might become a part of routine pregnancy management in the near future. Moreover, the ethical challenges associated with the introduction of MD-NIPT into routine clinical practice need to be carefully evaluated. Furthermore, more focus and attention should be directed towards the ethics of late paternity, paternal rights and paternal genetic guilt associated with pregnancies affected with PAE MDs.

Non-invasive Prenatal Testing, What Patients Do Not Learn, May Be Due to Lack of Specialist Genetic Training by Gynecologists and Obstetricians?

Platforms for "non-invasive prenatal testing" (NIPT), or also referred to as "non-invasive prenatal screening" (NIPS) have been available for over 10 years, and are the most recent tools available to obtain information about genetic condition(s) of an unborn child. The highly praised advantage of NIPT-screening is that results can provide early hints on the detection of fetal trisomies and gonosomal numerical aberrations as early as the 10th week of gestation onward, without any need for invasive procedures, such as amniocenteses or alternatives. Understandably, the public along with gynecologists and obstetricians eagerly await these early test results. Their general hope for normal (=negative) test results is also justified, as in >95% of the tested cases such an outcome is to be expected. However, pregnant women can be disappointed and confused, particularly regarding the genetic information and proposed care when the results are positive, and these emotions are also common with false-positive and false-negative NIPT results. Finally, such concerns in understanding the advantages and limitations of this routinely ordered screening tool end up at Clinical Geneticists and Genetic counselors. In this review, general background on NIPT, differences of NIPT platforms, advantages and limitations of NIPT, as well as consequences of insufficient counseling before and after NIPT are summarized. To provide comprehensive care in all pregnancies situations, professionals need a careful attitude toward offering NIPT along with specially training and qualifications in counseling for these procedures. Often it is gynecologists and obstetricians who discuss the use of NIPT with patients; however, although these physicians have a highly qualified background and knowledge in their respective specialty area(s), they may lack specific training on the interpretation of NIPT-screening results. These potential knowledge gaps must be closed quickly and comprehensively by the corresponding scientific societies to ensure optimal patient care.

Diagnosis of Fetal Abnormalities during the First Trimester

The quality of prenatal diagnosis of fetal abnormalities has advanced with improved resolution of ultrasound imaging and cytogenetic/molecular analysis. In this article, we briefly review the history of diagnosing fetal abnormalities and the current status of prenatal diagnosis during the first trimester (up to the first 14 weeks' gestation), focusing especially on fetal malformations and chromosomal abnormalities. As for detectable morphological abnormalities, roughly half of all major structural anomalies including those in the central nervous system, cardiovascular system and gastrointestinal system can be detected, if not definitely diagnosed. For screening of chromosomal abnormalities, especially for trisomy 21, ultrasound soft markers such as increased nuchal translucency, maternal serum markers and their combinations have been implemented. More recently, non-invasive prenatal testing, by analyzing cell-free DNA in maternal serum, is now available to detect chromosomal abnormalities with higher predictability. Although invasive chorionic villus sampling offers definite diagnosis for chromosomal abnormalities during the first trimester, non-invasive diagnostic techniques are patient-friendly and promising in the future perspectives on prenatal diagnosis for chromosomal abnormalities.

An assessment of the analytical performance of non-invasive prenatal testing (NIPT) in detecting sex chromosome aneuploidies: 34,717-patient sample in a single prenatal diagnosis Centre in China

OBJECTIVE

The present study aimed to evaluate the efficacy of a non-invasive prenatal test (NIPT) in the detection of the sex chromosome aneuploidies (SCAs) at our prenatal diagnosis centre.

METHODS

Among a cohort of 34,717 pregnancies, maternal plasma samples from our prenatal diagnosis centre were subject to analysis of SCAs using NIPT detection. Pregnant women with NIPT positive results of SCAs were recommended to undergo an invasive prenatal diagnosis (i.e. karyotyping and fluorescence in situ hybridization) to validate the prediction value of NIPT.

RESULTS

From 34,717 clinical pregnancies, 229 (0.66%) pregnancies were identified with SCAs. Of these, 78 (34.1%) cases were positive for 45,X and 151 (65.9%) cases comprised a sex chromosome trisomy. Of the 229 positive NIPT results, 193 (84.3%) cases had accepted an invasive diagnosis involving karyotyping analysis of the amniotic fluid, which confirmed 67 cases (34.7%) as true positive, as well as 126 cases (65.3%) as false positive. The positive predictive values were 23.07%, 50%, 36% and 27.27% respectively. The remaining 36 (15.7%) cases declined a prenatal diagnosis. The termination rates of 45,X, 47,XXY, 47,XXX and 47,XYY were 20.5%,46%,12.9% and 11.5% respectively.

CONCLUSIONS

NIPT demonstrated a lower accuracy in predicting monosomy X than sex chromosome trisomies. After invasive testing, the fetal chromosome with 45,X and 47,XXY were terminated more often than those with 47,XXX, 47,XYY. Because NIPT is a screening test, false positive/negative cases exist, and pre- and post-test counselling is essential for informing patients about the benefits and limitations of the test. Confirmatory testing of abnormal results is recommended prenatally or after birth, and the importance of confirmatory testing and benefits of early diagnosis should be addressed.

Evaluation of repeat testing of a non-sequencing based NIPT test on a Finnish general-risk population

Introduction

To evaluate the effect of repeating test failures using an automated, non‐sequencing based non‐invasive prenatal testing test on a general‐risk population in Finland.

Material and Methods

A total of 545 samples from women who represent the average‐risk population in Oulu, Finland were analyzed with Vanadis^® non‐invasive prenatal testing. Repeat testing of test failures was performed using a second sample. Results before and after repeat testing were compared with the reference outcome, as determined by clinical examination of neonates.

Results

There were eight test failures after first‐pass analysis, representing 1.5% of samples (95% CI 0.6%‐2.9%). Seven out of eight failures could be resolved by analysis of a second sample, thereby reducing the test failure rate from 1.5% to 0.2% (95% CI 0.0%‐1.0%).

Conclusions

Repeating test failures with a second plasma sample could significantly reduce the effective failure rate, thereby providing a way to effectively minimize test failures and further improving clinical utility and test performance.

Expanding the Scope of Non-invasive Prenatal Testing to Detect Fetal Chromosomal Copy Number Variations

Non-invasive prenatal testing (NIPT) for common fetal trisomies is effective. However, the usefulness of cell-free DNA testing to detect other chromosomal abnormalities is poorly understood. We analyzed the positive rate at different read depths in next-generation sequencing (NGS) and identified a strategy for fetal copy number variant (CNV) detection in NIPT. Pregnant women who underwent NIPT by NGS at read depths of 4–6 M and fetuses with suspected CNVs were analyzed by amniocentesis and chromosomal microarray analysis (CMA). These fetus samples were re-sequenced at a read depth of 25 M and the positive detection rate was determined. With the increase in read depth, the positive CNV detection rate increased. The positive CNV detection rates at 25 M with small fragments were higher by NGS than by karyotype analysis. Increasing read depth in NGS improves the positive CNV detection rate while lowering the false positive detection rate. NIPT by NGS may be an accurate method of fetal chromosome analysis and reduce the rate of birth defects.

Clinical utility of expanded non-invasive prenatal screening and chromosomal microarray analysis in high-risk pregnancy

OBJECTIVE

To evaluate the utility of expanded non-invasive prenatal screening (NIPS), compared with chromosomal microarray analysis (CMA), for the detection of chromosomal abnormalities in high-risk pregnancies.

METHODS

This was a multicenter retrospective study of singleton pregnancies at high risk for chromosomal abnormality. Patients who underwent expanded NIPS and CMA sequentially during pregnancy from 2015 to 2019 were included in the analysis. Pregnancies with a positive result for sex chromosome aneuploidy were excluded as the full details could not be retrieved. The utility of expanded NIPS and CMA for detection of chromosomal abnormalities in this cohort was compared by assessing the concordance between the results.

RESULTS

Of the 774 included high-risk pregnancies, 550 (71.1%) had a positive NIPS result, while a positive CMA result was detected in 308 (39.8%) cases. The rate of full or partial concordance between NIPS and CMA was 82.2%, 59.6% and 25.0% for trisomies 21, 18 and 13, respectively. For rare aneuploidies and segmental imbalances, NIPS and CMA results were fully or partially concordant in 7.5% and 33.3% of cases, respectively. Copy-number variants < 5 Mb were detected more often by CMA, with an incidence of 7.9% (61/774) compared with 3.1% (24/774) by NIPS. A genetic aberration was detected by CMA in 1 in 17 (5.8%) high-risk pregnancies that had a negative or non-reportable NIPS result.

CONCLUSION

CMA allows for comprehensive detection of genome-wide chromosomal abnormalities in high-risk pregnancies. CMA should be offered instead of expanded NIPS for high-risk pregnancies. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

National data on the early clinical use of non-invasive prenatal testing in public and private healthcare in Denmark 2013-2017

INTRODUCTION

In Denmark, non-invasive prenatal testing (NIPT) has been used since 2013. We aimed to evaluate the early clinical use of NIPT in Danish public and private healthcare settings before NIPT became an integrated part of the national guidelines on prenatal screening and diagnosis in 2017.

MATERIAL AND METHODS

NIPT data were collected between March 2013 and June 2017 from national public registries and private providers. Results from follow-up samples (chorionic villi, amniotic fluid, postnatal blood or fetal tissue) were included from The Danish Cytogenetics Central Registry and indications and outcome from The Danish Fetal Medicine Database.

RESULTS

A total of 3936 NIPT results were included in the study from public hospitals (n = 3463, 88.0%) and private clinics (n = 473, 12.0%). The total number of prenatal tests was 19 713 during the study period: 20% were NIPT analyses (n = 3936) and 80% invasive procedures (n = 15 777). Twenty-five percent of NIPTs in the private clinics were performed before gestational week 11⁺⁰ , whereas NIPT in public settings was used only after combined first trimester screening (P < .001). Regardless of indication, the national public sensitivity was 96.9% (95% CI 82.0%-99.8%) for trisomy 21, 100% (95% CI 46.3%-100%) for trisomy 18, 100% (95% CI 5.5%-100%) for trisomy 13, and 87.0% (95% CI 74.5%-92.4%) for any fetal chromosomal aberration. Forty-seven true-positive NIPT results included cases of common aneuplodies (trisomy 21, n = 31; trisomy 18, n = 5; and trisomy 13, n = 1), sex chromosomal aberrations (n = 7) and atypical chromosomal aberrations (n = 3). One false-negative NIPT result occurred (trisomy 21). Of 47 cases, 21 (45%) cases with a true-positive NIPT result resulted in live births by choice; 11 of these children had Down and 4 had Edwards syndrome.

CONCLUSIONS

The total number of NIPT analyses was low compared with the number of invasive procedures in the implementation period. In contrast to the generally high termination rate after a positive result following invasive testing in Denmark, a high proportion of true-positive NIPT results from the public setting resulted in live births. NIPT may be an important risk-free alternative to invasive testing for a minority of women in the public setting who wish to use prenatal genetic testing for information only and not for reproductive decision-making.