Perspectives of pregnant women on broadening the scope of noninvasive prenatal testing from screening for foetal aneuploidies to prediction of adverse pregnancy outcomes: A qualitative study.

OBJECTIVE: To explore the perspectives of pregnant women on broadening the scope of noninvasive prenatal testing (NIPT) from screening for foetal aneuploidies to prediction of adverse pregnancy outcomes. METHODS: Four online focus groups (n = 23 participants) and 14 individual semi-structured interviews were conducted. Participants included pregnant women with and without a history of adverse pregnancy outcomes. RESULTS: Both women at low and high risk of adverse pregnancy outcomes had a positive attitude towards using NIPT to predict adverse pregnancy outcomes. Perceived benefits included the possibility to potentially improve maternal and foetal outcomes by taking risk-reducing measures and/or intensified monitoring during pregnancy and the ability to mentally prepare for the potential adverse outcome. Perceived concerns included anxiety and stress caused by a high-risk test result, a false sense of control over pregnancy, and potential false reassurance. Additionally, women reasoned that broadening the scope of NIPT could increase the complexity of prenatal screening and raised concerns on the combined screening aims in one test (prediction of adverse pregnancy outcomes to improve foetal and maternal health vs. screening for foetal aneuploidies to increase reproductive autonomy). On a societal level, considerations on the risk of medicalising pregnancy and overall pressure to opt for NIPT were mentioned. CONCLUSION: In general, pregnant women have a positive attitude towards broadening the scope of NIPT to the prediction of pregnancy outcomes, although some concerns are acknowledged.

Fetal fraction of cell-free DNA in noninvasive prenatal testing and adverse pregnancy outcomes: a nationwide retrospective cohort study of 56,110 pregnant women.

BACKGROUND: Noninvasive prenatal testing by cell-free DNA analysis is offered to pregnant women worldwide to screen for fetal aneuploidies. In noninvasive prenatal testing, the fetal fraction of cell-free DNA in the maternal circulation is measured as a quality control parameter. Given that fetal cell-free DNA originates from the placenta, the fetal fraction might also reflect placental health and maternal pregnancy adaptation. OBJECTIVE: This study aimed to assess the association between the fetal fraction and adverse pregnancy outcomes. STUDY DESIGN: We performed a retrospective cohort study of women with singleton pregnancies opting for noninvasive prenatal testing between June 2018 and June 2019 within the Dutch nationwide implementation study (Trial by Dutch Laboratories for Evaluation of Non-Invasive Prenatal Testing [TRIDENT]-2). Multivariable logistic regression analysis was used to assess associations between fetal fraction and adverse pregnancy outcomes. Fetal fraction was assessed as a continuous variable and as <10th percentile, corresponding to a fetal fraction <2.5%. RESULTS: The cohort comprised 56,110 pregnancies. In the analysis of fetal fraction as a continuous variable, a decrease in fetal fraction was associated with increased risk of hypertensive disorders of pregnancy (adjusted odds ratio, 2.27 [95% confidence interval, 1.89-2.78]), small for gestational age neonates <10th percentile (adjusted odds ratio, 1.37 [1.28-1.45]) and <2.3rd percentile (adjusted odds ratio, 2.63 [1.96-3.57]), and spontaneous preterm birth from 24 to 37 weeks of gestation (adjusted odds ratio, 1.02 [1.01-1.03]). No association was found for fetal congenital anomalies (adjusted odds ratio, 1.02 [1.00-1.04]), stillbirth (adjusted odds ratio, 1.02 [0.96-1.08]), or neonatal death (adjusted odds ratio, 1.02 [0.96-1.08]). Similar associations were found for adverse pregnancy outcomes when fetal fraction was <10th percentile. CONCLUSION: In early pregnancy, a low fetal fraction is associated with increased risk of adverse pregnancy outcomes. These findings can be used to expand the potential of noninvasive prenatal testing in the future, enabling the prediction of pregnancy complications and facilitating tailored pregnancy management through intensified monitoring or preventive measures.

Association between low fetal fraction in cell-free DNA screening and fetal chromosomal aberrations: A systematic review and meta-analysis.

OBJECTIVE: To perform a systematic review and meta-analysis of the available literature on low fetal fraction (LFF) in cell-free DNA (cfDNA) screening and the risk of fetal chromosomal aberrations. METHOD: We searched articles published between January 2010 and May 2021 in PubMed and EMBASE databases. Risk of bias was assessed using QUADAS-2. RESULTS: Twenty-seven studies met the inclusion criteria, comprising data of 243,700 singleton pregnancies. Compared to normal fetal fraction, LFF was associated with a higher risk of trisomy 13 (OR 5.99 [3.61-9.95], I 2 of heterogeneity = 0%, n = 22 studies), trisomy 18 (OR 4.46 [3.07-6.47], I 2  = 0%, n = 22 studies), monosomy X (OR 5.88 [2.34-14.78], I 2  = 18%, n = 10 studies), and triploidy (OR 36.39 [9.83-134.68], I 2  = 61%, n = 6 studies), but not trisomy 21 (OR 1.25 [0.76-2.03], I 2  = 36%, n = 23 studies). LFF was also associated with a higher risk of various other types of fetal chromosomal aberrations (OR 4.00 [1.78-9.00], I 2  = 2%, n = 11 studies). Meta-analysis of proportions showed that absolute rates of fetal chromosomal aberrations ranged between 1% and 2% in women with LFF. A limitation of this review is the potential risk of ascertainment bias because of differences in outcome assessment between pregnancies with LFF and those with normal fetal fraction. Heterogeneity in population characteristics or applied technologies across included studies may not have been fully addressed. CONCLUSION: An LFF test result in cfDNA screening is associated with an increased risk of fetal trisomy 13, trisomy 18, monosomy X, and triploidy, but not trisomy 21. Further research is needed to assess the association between LFF and other specific types of fetal chromosomal aberrations.

Variability in Fetal Fraction Estimation: Comparing Fetal Fractions Reported by Noninvasive Prenatal Testing Providers Globally.

BACKGROUND: Fetal fraction (FF) measurement is considered important for reliable noninvasive prenatal testing (NIPT). Using minimal FF threshold as a quality parameter is under debate. We evaluated the variability in reported FFs of individual samples between providers and laboratories and within a single laboratory. METHODS: Genomic quality assessment and European Molecular Genetics Quality Network provide joint proficiency testing for NIPT. We compared reported FFs across all laboratories and stratified according to test methodologies. A single sample was sequenced repeatedly and FF estimated by 2 bioinformatics methods: Veriseq2 and SeqFF. Finally, we compared FFs by Veriseq and SeqFF in 87 351 NIPT samples. RESULTS: For each proficiency test sample we observed a large variability in reported FF, SDs and CVs ranging from 1.7 to 3.6 and 17.0 to 35.8, respectively. FF measurements reported by single nucleotide polymorphism-based methods had smaller SDs (0.5 to 2.4) compared to whole genome sequencing-based methods (1.8 to 2.9). In the internal quality assessment, SDs were similar between SeqFF (SD 1.0) and Veriseq v2 (SD 0.9), but mean FF by Veriseq v2 was higher compared to SeqFF (9.0 vs 6.4, P 0.001). In patient samples, reported FFs were on average 1.12-points higher in Veriseq than in SeqFF (P 0.001). CONCLUSIONS: Current methods do not allow for a reliable and consistent FF estimation. Our data show estimated FF should be regarded as a laboratory-specific range, rather than a precise number. Applying strict universal minimum thresholds might result in unnecessary test failures and should be used with caution.

Association between low fetal fraction in cell-free DNA testing and adverse pregnancy outcome: A systematic review.

OBJECTIVE: Low fetal fraction (LFF) in prenatal cell-free DNA (cfDNA) testing is an important cause of test failure and no-call results. LFF might reflect early abnormal placentation and therefore be associated with adverse pregnancy outcome. Here, we review the available literature on the relationship between LFF in cfDNA testing and adverse pregnancy outcome. METHOD: A systematic literature search was conducted in MEDLINE and EMBASE up to November 1, 2020. RESULTS: Five studies met the criteria for inclusion; all were retrospective observational cohort studies. The cohort sizes ranged from 370 to 6375 pregnancies, with all tests performed in the first trimester or early second trimester. A 4% cutoff for LFF was used in two studies, two studies used the 5th and 25th percentiles, respectively, and one study used a variety of cutoff values for LFF. LFF in prenatal cfDNA testing was observed to be associated with hypertensive disease of pregnancy, small for gestational age neonates, and preterm birth. Conflicting results were found regarding the association between LFF and gestational diabetes mellitus. CONCLUSIONS: LFF in cfDNA testing is associated with adverse pregnancy outcome,specifically pregnancy-related hypertensive disorders, preterm birth, and impaired fetal growth related to placental dysfunction. Since the available evidence is limited, a large prospective cohort study on the relationship between fetal fraction and pregnancy outcomes is needed.

Low fetal fraction in cell-free DNA testing is associated with adverse pregnancy outcome: Analysis of a subcohort of the TRIDENT-2 study.

OBJECTIVES: To assess the association between low fetal fraction (FF) in prenatal cell-free DNA (cfDNA) testing and adverse pregnancy outcomes. METHODS: We conducted a retrospective cohort study of participants of the TRIDENT-2 study (Dutch nationwide government-supported study offering cfDNA screening for fetal aneuploidies) who received a failed test result due to low FF (<4%) between April 2017 until February 2018. Outcome measures included pregnancy-induced hypertension (PIH), pre-eclampsia (PE), small for gestational age neonates (SGA), spontaneous preterm birth (sPTB), gestational diabetes mellitus (GDM), chromosomal aberrations, and congenital structural anomalies. RESULTS: Test failure due to low FF occurred in 295 women (1.12% of tests performed). Information regarding pregnancy outcomes was available for 96.3% of these women. The incidence of PIH, PE, SGA, sPTB, and GDM was 11.2%, 4.1%, 7.3%, 5.1%, and 14.8%, respectively. The prevalence of chromosomal aberrations and congenital structural anomalies was 1.4% and 4.1%, respectively. Incidences of PIH, PE ≥ 34 weeks of gestation, GDM, and prevalence of aneuploidy and congenital structural anomalies were higher in women with low FF compared to the general Dutch obstetric population. CONCLUSION: Low FF is associated with adverse pregnancy outcomes. The value of FF in the prediction of these outcomes needs to be further established.