Cell-free fetal DNA versus maternal serum screening for trisomy 21 in pregnant women with and without assisted reproduction technology: a prospective interventional study

Analysis of retest reliability for pregnant women undergoing cfDNA testing with a no-call result

BACKGROUND

Determining the reasons for unreportable or no-call cell-free DNA (cfDNA) test results has been an ongoing issue, and a consensus on subsequent management is still lacking. This study aimed to explore potential factors related to no-call cfDNA test results and to discuss whether retest results are reliable.

METHODS AND RESULTS

This was a retrospective study of women with singleton pregnancies undergoing cfDNA testing in 2021. Of the 9871 pregnant patients undergoing cfDNA testing, 111 had a no-call result, and their results were compared to those of 170 control patients. The no-call rate was 1.12% (111/9871), and the primary cause for no-call results was data fluctuation (88.29%, 98/111). Medical conditions were significantly more frequent in the no-call group than in the reportable results group (P < 0.001). After retesting, 107 (107/111, 96.40%) patients had a result, and the false-positive rate (FPR) of retesting was 10.09% (10.09%, 11/109). In addition, placental lesions were more frequent in the no-call group than in the reportable results group (P = 0.037), and 4 patients, all in the no-call group, experienced pregnancy loss.

CONCLUSIONS

Pregnant women with medical conditions are more likely to have a no-call result. A retest is suggested for patients with a no-call result, but retests have a high FPR. In addition, pregnant women with a no-call result are at increased risk of adverse pregnancy outcomes. In conclusion, more attention should be given to pregnant women for whom a no-call cfDNA result is obtained.

Preserving women's reproductive autonomy while promoting the rights of people with disabilities?: the case of Heidi Crowter and Maire Lea-Wilson in the light of NIPT debates in England, France and Germany

On July 2021, the UK High Court of Justice heard the Case CO/2066/2020 on the application of Heidi Crowter who lives with Down's syndrome, and Máire Lea-Wilson whose son Aidan has Down's syndrome. Crowter and Lea-Wilson, with the support of the disability rights campaign, 'Don't Screen Us Out', have been taking legal action against the Secretary of State for Health and Social Care (the UK Government) for a review of the 1967 Abortion Act: the removal of section 1(1)(d) making termination of pregnancy lawful for 'severe' fetal indications detected after 24 weeks' gestation. On 23 September 2021, the High Court dismissed the claim. This action came at a time when non-invasive prenatal testing (NIPT) was introduced into the NHS England Fetal Anomaly Screening Programme for the trisomies 21, 13 and 18. The implementation of NIPT has been heavily criticised, in particular by 'Don't Screen Us Out' campaigners, for increasing fetal selection and discrimination of people living with disabilities. The case of Crowter and Lea-Wilson echoes debates in other European countries such as in France and Germany, where the introduction of NIPT in the public healthcare system has provoked equally vehement public reactions and discussions. The comparison between these three countries allows contextualising the public discourses around NIPT and the ground for termination of pregnancy in relation to different socio-cultural and political contexts. We examine how each country, and particularly England, deals with the conflict between the principles of promoting the rights of people living with disabilities and preserving women's reproductive autonomy.

Cell-free fetal DNA testing performance and fetal fraction estimation are not affected in ART-conceived pregnancies

STUDY QUESTION

Does ART-based conception influence fetal fraction (FF) estimation and cell-free fetal DNA (cffDNA) testing performance?

SUMMARY ANSWER

Mode of conception (ART versus natural) does not impact FF estimation or cffDNA test informativity rates.

WHAT IS KNOWN ALREADY

Pregnancies achieved via ART are increasing, and cffDNA testing is displacing traditional prenatal screening methods due to its high sensitivity and specificity and noninvasive nature. However, conflicting data exist on cffDNA testing performance and FF in ART pregnancies compared with natural pregnancies.

STUDY DESIGN, SIZE, DURATION

We performed a case-control study that included 21 558 consecutive pregnancies (spontaneous, n = 15 707; ART, n = 5851). ART-conceived pregnancies were stratified into two groups according to oocyte origin. Samples were collected from April 2015 to September 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study included women from different centers worldwide. Blood samples were drawn from the 10th week of gestation onward. Massive parallel whole-genome sequencing was used to analyze cffDNA content in blood plasma. Two different types of technologies (single-end and paired-end) were applied because of analysis technology changes made by the sequencing provider over time. FF was determined using different methods depending on the type of technology used. Cases with an FF <2% or with failure in any quality control metrics were classified as noninformative. An analysis of covariance model was selected to identify which qualitative (sequencing methodology, mode of conception, type (i.e. multiplicity) of gestation and age (women >35 or <35 years old)) and quantitative (gestational age, BMI) variables were predictors of FF value. Multinomial logistic regression was used to evaluate whether the mode of conception impacted cffDNA testing performance.

MAIN RESULTS AND THE ROLE OF CHANCE

A univariate t-test demonstrated no significant differences in FF values between ART (median FF = 9.2%) and spontaneous pregnancies (median FF = 9.2%). Also, a multivariate analysis showed that the mode of conception, did not strongly impact the percentage of FF. ART-treated women showed a lower incidence of high-risk cffDNA results compared to women who conceived naturally, specifically for trisomy (T)21 (0.7% versus 1.3%, P = 0.001) and T18 (0.1% versus 0.3%, P = 0.001). A multivariate model stratified by type of aneuploidy suggested that these differences were conditioned by oocyte origin, especially for the T21 risk classification (P < 0.0001). False-positive rates (FPRs) were significantly higher in the ART population, mainly for T13 (P = 0.001) and sexual chromosome aneuploidies (SCAs; P < 0.001). A multivariate model suggested that the differences observed in SCAs were caused by sequencing modality rather than by mode of conception. Likewise, ART-treated women who used their own oocytes had a higher probability of a false positive for T13 (P = 0.004).

LIMITATIONS, REASONS FOR CAUTION

Our study lacks follow-up data for low- and high-risk cases of both ART-conceived and naturally conceived pregnancies. Therefore, the results comparing FPR in both populations should be interpreted carefully. Also, collecting information about different ART modalities and regarding preimplantation genetic testing for aneuploidy treatments would help draw definite explanations for the trends observed in this study.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study that demonstrates, with a large sample size, that FF is not influenced by mode of conception, demystifying the notion that patients undergoing ART have a higher probability of noninformative cffDNA testing results. Multivariate models stratified by oocyte origin and type of aneuploidy demonstrated that ART-conceived pregnancies do not have a higher probability of classification as a high-risk pregnancy in prenatal testing. This information is especially valuable to clinicians and genetic counselors when informing patients about the risks and limitations of cffDNA testing in ART pregnancies.

STUDY FUNDING/COMPETING INTEREST(S)

This study was financially supported by Igenomix Lab S.L.U. All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Non-invasive Prenatal Testing in Pregnancies Following Assisted Reproduction

In the decade since non-invasive prenatal testing (NIPT) was first implemented as a prenatal screening tool, it has gained recognition for its sensitivity and specificity in the detection of common aneuploidies. This review mainly focuses on the emerging role of NIPT in pregnancies following assisted reproductive technology (ART) in the light of current evidence and recommendations. It also deals with the challenges, shortcomings and interpretational difficulties related to NIPT in ART pregnancies, with particular emphasis on twin and vanishing twin pregnancies, which are widely regarded as the Achilles' heel of most pre-natal screening platforms. Future directions for exploration towards improving the performance and extending the scope of NIPT are also addressed.

Systematic evidence-based review: The application of noninvasive prenatal screening using cell-free DNA in general-risk pregnancies

PURPOSE

Noninvasive prenatal screening (NIPS) using cell-free DNA has been assimilated into prenatal care. Prior studies examined clinical validity and technical performance in high-risk populations. This systematic evidence review evaluates NIPS performance in a general-risk population.

METHODS

Medline (PubMed) and Embase were used to identify studies examining detection of Down syndrome (T21), trisomy 18 (T18), trisomy 13 (T13), sex chromosome aneuploidies, rare autosomal trisomies, copy number variants, and maternal conditions, as well as studies assessing the psychological impact of NIPS and the rate of subsequent diagnostic testing. Random-effects meta-analyses were used to calculate pooled estimates of NIPS performance (P < .05). Heterogeneity was investigated through subgroup analyses. Risk of bias was assessed.

RESULTS

A total of 87 studies met inclusion criteria. Diagnostic odds ratios were significant (P < .0001) for T21, T18, and T13 for singleton and twin pregnancies. NIPS was accurate (≥99.78%) in detecting sex chromosome aneuploidies. Performance for rare autosomal trisomies and copy number variants was variable. Use of NIPS reduced diagnostic tests by 31% to 79%. Conclusions regarding psychosocial outcomes could not be drawn owing to lack of data. Identification of maternal conditions was rare.

CONCLUSION

NIPS is a highly accurate screening method for T21, T18, and T13 in both singleton and twin pregnancies.

Análisis de concordancia entre la prueba prenatal no invasiva (NIPT) y el cariotipo prenatal para la detección de aneuploidías fetales

Introducción. La prueba prenatal no invasiva (NIPT, por su sigla en inglés) es una prueba de tamización de aneuploidías fetales con una mayor sensibilidad y especificidad que la tamización bioquímica prenatal tradicional. Objetivo. Evaluar la concordancia entre la NIPT y el cariotipo prenatal para la detección de aneuploidías fetales en embarazos de alto riesgo de dichas anomalías Materiales y métodos. Estudio piloto prospectivo realizado entre septiembre de 2019 y diciembre de 2020 en 20 pacientes con gestaciones clasificadas como de alto riesgo para aneuploidías fetales con base en los hallazgos ecográficos y atendidas en Bogotá y Medellín, Colombia. A cada paciente se le realizó una NIPT y una prueba invasiva confirmatoria (cariotipo prenatal). La concordancia entre ambos métodos se determinó mediante el coeficiente kappa de Cohen (nivel de significancia p<0.05), donde valores >0.7 se consideraron como un buen nivel de concordancia. Resultados. En 3 de las 20 gestaciones (15%) se detectaron aneuploidías mediante estudio citogenético invasivo: trisomía 21, trisomía 18 y monosomía X. La NIPT detectó la trisomía 21 y la monosomía X, pero falló en detectar la trisomía 18. Respecto al análisis de concordancia, el coeficiente de kappa de Cohen entre la NIPT y cariotipo prenatal fue 0.77, 1.0 y 0 para trisomía 21, monosomía X, trisomía 18, respectivamente. Además, la NIPT detectó 67% de las aneuploidías. Conclusión. En el presente estudio, primero en realizarse en Colombia, se observó una buena concordancia entre la NIPT y la prueba invasiva (cariotipo prenatal) para la detección de aneuploidías. Sin embargo, los resultados aquí reportados enfatizan la recomendación de utilizar la NIPT como prueba de tamización y no como prueba diagnóstica.

Comparison of the Fetal Fraction of Cell-Free DNA in In-Vitro Fertilization (IVF) Versus Natural Conception Evaluation of the Fetal Fraction With IVF Parameters

Background

As the offspring of assisted reproduction techniques (ARTs) have become a substantial proportion of the population, increased attention has been placed on the safety of ART. Investigators have focused on identifying a tool that combines molecular or biological tests that can predict the outcomes of in-vitro fertilization (IVF) or intracytoplasmic sperm injection and the resulting pregnancy after ART-mediated embryo implantation. This study aimed to answer the following questions: is there a difference between natural conception and IVF pregnancies regarding fetal fraction (FF) of cell-free DNA (cfDNA) in maternal age, birth weight, gender, and gestational age? Is there a difference between FF concentration regarding the parameters of IVF as possible predictive factors affecting the outcomes of IVF?

Methodology

This study included 31 women with singleton pregnancies conceived via IVF who underwent cell-free fetal DNA (cffDNA) screening for trisomy 13, 18, and 21; sex determination; and FF. The control group included 55 women who experienced natural conception. For all women, anthropometric characteristics such as age, weight, height, and body mass index (BMI) were recorded. For the IVF group, early follicular phase values of follicle-stimulating hormone, luteinizing hormone, prolactin, anti-müllerian hormone, thyroid-stimulating hormone, and estradiol were recorded.

Results

The natural conception and IVF groups were similar regarding maternal age, BMI of the mother, gender, birth weight, and gestational age. FF was not significantly different between the natural conception and IVF groups (10 (3.8) vs. 9 (2.6); p = 0.144). The results were similar after adjusting for maternal age via regression analysis. cfDNA was not associated with maternal age, birth weight, gender, or gestational age in the entire study sample or separately for the natural conception and IVF groups. No significant correlation was found between cfDNA and IVF parameters.

Conclusions

The FF is an important factor for non-invasive prenatal testing (NIPT) accuracy. Several studies have found a reduction in FF in pregnancies following ART compared with natural conception, while other studies have presented no differences in the FF. All researchers agree on the importance of NIPT; however, knowledge on how the FF is affected in ART pregnancies compared with naturally conceived pregnancies is very limited. In this study, no difference in FF for the IVF group compared with natural conception women was observed. The cffDNA concentrations in maternal serum do not appear to be affected in IVF conception. We suggest that FF is an independent factor compared with IVF parameters.

The ethical landscape(s) of non-invasive prenatal testing in England, France and Germany: findings from a comparative literature review

Since 2019, England, France and Germany have started offering NIPT as a publicly funded second-tier test for common chromosomal aneuploidies (trisomy 21, 18 and/or 13). Despite these benefits, the introduction of NIPT into routine prenatal care also raises a number of ethical concerns. In this paper, we analyse how these issues are discussed differently across countries, echoing the different socio-political particularities and value-systems that shape the use and regulation of NIPT in a specific country. The international comparison between England, France and Germany shows how each country defines the principle of reproductive autonomy and weighs it against other principles and values, such as, human dignity, disability rights and the duty of care of health professionals. In terms of methodology, our literature review focuses on arguments and regulations of prenatal testing and reproductive choices (specifically on NIPT), through the investigation of regulatory, parliamentary, scientific, medical, association, institutional and media sources. The comparative review helps to better understand ethical questions discussed with regard to NIPT, and, more broadly, to prenatal genomic testing, and the limits associated with reproductive autonomy in the three countries studied. Whereas reproductive autonomy is valued in each country, it is understood and implemented differently depending on the socio-cultural context, and on what other principles are evoked and how they are defined.

Fetal fraction of cell-free DNA in pregnancies after fresh or frozen embryo transfer following assisted reproductive technologies

STUDY QUESTION

Is the fetal fraction (FF) of circulating cell-free DNA (cfDNA) affected in pregnancies following ART treatment with either fresh or frozen embryo transfer (ET) compared with natural conception?

SUMMARY ANSWER

This study shows a significant reduction in the FF in ART patients compared with naturally conceived pregnancies, which seems to be more pronounced after fresh ET compared with frozen ET.

WHAT IS KNOWN ALREADY

Non-invasive prenatal testing (NIPT) is based on cfDNA in maternal blood, of which about 10% is of placental origin and thus represents the fetal karyotype. Validation studies have demonstrated a high sensitivity, specificity and positive predictive value of NIPT for the detection of fetal trisomy 21, 18 and 13. Nevertheless, the FF of cfDNA is an important factor for NIPT test accuracy. Several studies have found a reduction in FF for pregnancies following ART in comparison with natural conception. However, knowledge on how the FF is affected in ART pregnancies after fresh ET compared with frozen ET is very limited.

STUDY DESIGN, SIZE, DURATION

The study was designed as a case-control study. A total of 54 women with an ongoing pregnancy following ART treatment were included. After exclusion for different reasons, statistical analyses were based on 23 NIPT samples from pregnant women treated with fresh ET and 26 NIPT samples from pregnant women treated with frozen-thawed ET in a modified natural cycle. Women were included between February 2018 and November 2018. The results were compared with a control group of 238 naturally conceived pregnancies with a high-risk result from the combined first trimester screening (cFTS).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study included women from the Fertility Clinics at Copenhagen University Hospital Hvidovre and Copenhagen University Hospital Rigshospitalet. Blood samples for NIPT analysis were drawn between 11 + 0 and 14 + 2 weeks of gestation and were all analyzed at the NIPT Center at Copenhagen University Hospital Hvidovre. The NIPT-test was performed by massive-parallel whole-genome sequencing. The FF was determined using the SeqFF algorithm.

MAIN RESULTS AND THE ROLE OF CHANCE

We found a reduction in FF in ART patients compared with naturally conceived pregnancies, and the reduction was more pronounced for ART pregnancies after fresh ET (mean FF = 0.049) compared with frozen ET (mean FF = 0.063) (multivariate analysis adjusted for maternal BMI, P = 0.02). Another multivariate analysis, adjusted for BMI and multiples of median (MoM) values for pregnancy-associated plasma protein-A (PAPP-A), demonstrated a significantly reduced FF for ART pregnancies (mean FF = 0.056) compared with naturally conceived pregnancies (mean FF = 0.072) (P < 0.0001). We found that FF was significantly reduced with increasing maternal BMI (P < 0.0001) and with decreasing MoM values of PAPP-A (P = 0.003).

LIMITATIONS, REASONS FOR CAUTION

A limitation of our study design was the relatively small sample size. Another limitation was that the control group was not matched with the ART-treated women. The majority of the women from the control group had a high risk from cFTS, thereby their biochemical markers were diverging. However, the biochemical markers for the ART-treated women with fresh or frozen ET were not divergent within the subgroups.

WIDER IMPLICATIONS OF THE FINDINGS

Concurrent with other studies demonstrating a reduced FF for singleton pregnancies after ART treatment compared with naturally conceived pregnancies, we found a reduction in FF between the two groups. This is one of the first studies to examine FF in ART pregnancies after fresh ET compared with frozen ET, hence the existing knowledge is limited. We find that FF is even more reduced in pregnancies following fresh ET compared with frozen ET, which might possibly reflect the predisposition of being small for gestational age after fresh ET compared with natural cycle frozen ET.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the A.P. Møller og Hustru Chastine Mc-Kinney Møllers Fond til almene Formaal (the A.P. Møller Foundation for General Purposes). All authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

NA.

Clinical Review of Noninvasive Prenatal Testing: Experience from 551 Pregnancies with Noninvasive Prenatal Testing-Positive Results in a Tertiary Referral Center

A total of 551 pregnancies with positive results for noninvasive prenatal testing (NIPT) using traditional karyotyping and chromosomal microarray analysis were analyzed. Confirmatory results, positive predictive values, etiology exploration of false-positive results, and pregnancy outcomes were recorded. The study demonstrated that NIPT performed better in predicting trisomy 21 and trisomy 18 for pregnancies with advanced maternal age than for pregnancies with young maternal age; as for trisomy 13 and sex chromosomal aneuploidy (SCA) prediction, there was no significant difference between the two groups. The positive predictive values for trisomy 21, trisomy 18, trisomy 13, and SCA showed no significant upward trend when compared based on specific age categories (an interval of 5 years), which suggested that NIPT-positive result deserves equal attention from both providers and patients regardless of maternal age. In addition, the termination rates of 45,X, 47,XXY, 47,XXX, and 47,XYY were 100% (2/2), 92.9% (26/28), 33.3% (5/15), and 9.5% (2/21), respectively, which demonstrated that the decision-making regarding pregnancies varied greatly according to the types of SCAs, and further reinforce the importance of confirmatory prenatal diagnosis. The current study also supported the viewpoint that confined placental mosaicism and maternal mosaicism were the important etiology of false-positive results.

Non-invasive prenatal testing in the context of IVF and PGT-A

The high incidence of chromosome aneuploidy in human gametes and embryos is a major cause of in vitro fertilization (IVF) failure and miscarriage. In order to improve live birth rates with single embryo transfer, the use of preimplantation genetic testing for aneuploidy (PGT-A) has significantly increased. PGT encompasses methods that allow embryos to be tested for inherited conditions or screened for chromosomal abnormalities. However, PGT-A is a screening method and results can never be used to definitively predict the chromosomal status of the embryo and fetus. The objective of this manuscript is to review prenatal screening and diagnostic methods available in pregnancies conceived by IVF-PGT-A.

A Pictorial Ultrasound Essay of Gestational Trophoblastic Disease

Gestational trophoblastic disease (GTD) includes a wide variety of clinical and histopathologic entities that require prompt identification and definition by the integration of clinical, laboratory, and imaging data. Recently, the role of grayscale ultrasound and spectral and power/color Doppler techniques has become pivotal in the diagnosis, staging, and management of GTD, thanks to both technical improvements and the growing expertise of dedicated operators. The aim of this essay is to summarize the most recent data on the ultrasound and Doppler findings of GTD and to provide a pictorial overview, including useful prognostic and therapeutic implications for clinical practice.

Profile of women choosing the Harmony® Prenatal Test

INTRODUCTION

The Harmony® Prenatal Test, a noninvasive cell-free DNA (cfDNA) method for major trisomies has been available since January 2013 at our unit, and tests were sent to the Ariosa Clinical Laboratory Improvement Amendments (CLIA) laboratory in California. From July 2017 onward, prenatal cfDNA has been reimbursed in Belgium for all pregnancies; however, since then samples are sent to a local laboratory. Little data are available on patient's profile and choices toward cfDNA and on the performance of local technology transfer centers. Areas covered: The profiles and choices of women regarding this test were evaluated. Further, the performance of cfDNA at the local laboratory was compared to the one in California. Our results showed that women from the Netherlands, as compared to Belgium, were more likely to undergo cfDNA testing for maternal request and would be less likely to undergo karyotyping if cfDNA were unavailable, therefore are better candidates for cfDNA testing, when this is used as first-line screening. Expert commentary: Our findings highlight the importance of conducting these types of studies, before decisions about clinical implementation are made by national governments and ministries of health.

Autoimmune disorders but not heparin are associated with cell-free fetal DNA test failure

Background

Recent studies have suggested a possible association between heparin treatment at the time of cell-free DNA (cfDNA) testing and a non-reportable result. However, these studies lack of proper methodology and had a low level of proof to firmly incriminate heparin. Our objective was to investigate further the relationship between heparin treatment and cfDNA test results.

Methods

Two complementary approaches were used for the demonstration. First, we conducted a retrospective analysis of a cohort of patients with a singleton pregnancy, screened for aneuploidies by using cfDNA, but with a non-reportable cfDNA result. We included patients between 2013 and 2016 including the patients from the DEPOSA study as controls. CfDNA testing was performed by massive parallel sequencing by using a whole-genome approach. A multiple logistic regression was used to account for the influence of the variables included. Second, we performed in vitro experiments on mimic samples containing increased concentrations of heparin.

Results

Of 9867 singleton pregnancies tested during the inclusion period, 58 (0.59%) had a non-reportable result and were compared to 295 control patients. Fifteen (25.9%) and 20 (6.8%) patients were treated with heparin in the group with a non-reportable cfDNA result and with a successful assay, respectively. In multivariable analysis, an increased calculated risk at the first-trimester combined screening (OR 28.8 CI 9.76–85.15, p < 0.001), maternal weight (OR 1.03, CI 1.01–1.06, p = 0.01), and the presence of an autoimmune disease (OR 10.38, CI 1.62–66.53, p = 0.01) were the only characteristics associated with a non-reportable result. In vitro experiments showed that heparin had no impact on fetal fraction measurement or the final result, no matter what the dose tested.

Conclusions

Treatment by heparin had no impact on cfDNA screening test for aneuploidies, while the presence of an autoimmune disorder is an independent predictor of a non-reportable result.