Risk of miscarriage following amniocentesis or chorionic villus sampling: systematic review of literature and updated meta-analysis

Noninvasive prenatal diagnosis by genome-wide haplotyping of cell-free plasma DNA

PURPOSE

Whereas noninvasive prenatal screening for aneuploidies is widely implemented, there is an increasing need for universal approaches for noninvasive prenatal screening for monogenic diseases. Here, we present a cost-effective, generic cell-free fetal DNA (cffDNA) haplotyping approach to scan the fetal genome for the presence of inherited monogenic diseases.

METHODS

Families participating in the preimplantation genetic testing for monogenic disorders (PGT-M) program were recruited for this study. Two hundred fifty thousand single-nucleotide polymorphisms (SNPs) captured from maternal plasma DNA along with genomic DNA from family members were massively parallel sequenced. Parental genotypes were phased via an available genotype from a close relative, and the fetal genome-wide haplotype and copy number were determined using cffDNA haplotyping analysis based on estimation and segmentation of fetal allele presence in the maternal plasma.

RESULTS

In all families tested, mutational profiles from cffDNA haplotyping are consistent with embryo biopsy profiles. Genome-wide fetal haplotypes are on average 97% concordant with the newborn haplotypes and embryo haplotypes.

CONCLUSION

We demonstrate that genome-wide targeted capture and sequencing of polymorphic SNPs from maternal plasma cell-free DNA (cfDNA) allows haplotyping and copy-number profiling of the fetal genome during pregnancy. The method enables the accurate reconstruction of the fetal haplotypes and can be easily implemented in clinical practice.

Decisions Parents Make When Faced With Potentially Life-Limiting Fetal Diagnoses and the Importance of Perinatal Palliative Care

When parents face a potentially life-limiting fetal diagnosis in pregnancy, they then have a series of decisions to make. These include confirmatory testing, termination, and additional choices if they choose to continue the pregnancy. A perinatal palliative team provides a safe, compassionate, and caring space for parents to process their emotions and discuss their values. In a shared decision-making model, the team explores how a family's faith, experiences, values, and perspectives shape the goals for care. For some families, terminating a pregnancy for any reason conflicts with their faith or values and pursuing life prolonging treatments in order to give their baby the best chances for survival is the most important. For others, having a postnatal confirmatory diagnosis of a life limiting or serious medical condition gives them the assurance they need to allow their child a natural death. Others want care to be comfort-focused in order to maximize the time they have to be together as a family. Through this journey, a perinatal palliative team can provide the support and encouragement for families to express their goals and wishes, as well as find meaning and hope.

First-trimester screening-biomarkers and cell-free DNA

Background: The introduction of cell-free DNA into clinical practice has changed the screening approach. Healthcare professionals and future parents tend to overestimate NIPT (noninvasive prenatal testing) capabilities despite its relatively high cost and limited information.Objective: In this review, our aim was to survey how various countries have introduced contingent screening models and to discuss the advantages and disadvantages of the combined screening test and the use of NIPT.Data source: The Web of Science, PubMed database and institutional websites were searched for information regarding screening approaches and the implementation in different countries.Results: There are nine countries and regions that have already approved contingent screening test, while others (e.g. Australia) are discussing the implementation of contingent screening versus universal use of NIPT. There are several recent meta-analyses debating whether to use NIPT for universal screening for trisomies and other fetal conditions.Conclusions: NIPT is a reasonable option as an advanced screening test for trisomy 21, 18 and 13 only. Introducing screening by NIPT instead of a first-trimester screening will cause the loss of other valuable information including accurate dating of pregnancy, diagnosing major structural fetal abnormalities and multiple pregnancies at an early gestational age. Additionally, the opportunity to screen for early preeclampsia will be lost. Currently, the price for NIPT is still high adding extra strain on publicly funded health systems.

Procedure-related risk of miscarriage following chorionic villus sampling and amniocentesis

OBJECTIVES

To estimate the procedure-related risks of miscarriage following chorionic villus sampling (CVS) and amniocentesis in a large unselected screened population, and to determine whether these risks are consistent with those reported in systematic reviews and meta-analyses.

METHODS

This was a retrospective cohort study carried out on data obtained from a large fetal medicine unit in the UK between January 2009 and May 2018. We included all women with singleton pregnancy who booked for pregnancy care at our unit before 20 weeks' gestation, after excluding those with multiple pregnancy, major fetal defect, pregnancy termination and loss to follow-up. We estimated the risk of miscarriage in women who underwent a CVS or amniocentesis as well as in those who did not have an invasive procedure. The procedure-related risk of miscarriage was estimated as risk difference (95% CI) between the two groups. Univariate and multivariate regression analyses were used to derive odds ratios (95% CI) and determine which maternal and pregnancy characteristics provided a significant contribution in the prediction of miscarriage and whether CVS or amniocentesis provided a significant independent contribution.

RESULTS

During the study period, 45 120 singleton pregnancies were booked for pregnancy care at our hospital, of which 1546 had an invasive procedure. We excluded 1429 (3.2%) pregnancies due to fetal defects, termination of pregnancy or missing outcomes. Of the 43 691 pregnancies included in the study population, 861 underwent CVS and 375 amniocentesis. In pregnancies that underwent CVS, the risk of miscarriage was 1.5% (13/861), compared with 1.2% (476/39 152) in pregnancies that had first-trimester combined screening and did not have an invasive procedure (P = 0.437). In pregnancies that underwent an amniocentesis, the risk of miscarriage was 0.8% (3/375), compared with 1.2% (491/42 463) in those that did not undergo an invasive procedure (P = 0.520). Univariate and multivariate regression analysis demonstrated that there was no significant contribution in the prediction of the risk of miscarriage from CVS (P = 0.399 and P = 0.592, respectively) or amniocentesis (P = 0.543 and P = 0.550, respectively). The risk of procedure-related loss attributed to CVS was 0.29% (95% CI, -0.53 to 1.12%) and that following amniocentesis was -0.36% (95% CI, -1.26 to 0.55%), which was not significantly different from the risk in women who did not have any procedure.

CONCLUSIONS

The procedure-related risks of miscarriage following CVS and amniocentesis in our study are considerably lower than those currently quoted and are consistent with the estimates of such risks reported by systematic reviews and meta-analyses. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Indications for genetic testing leading to termination of pregnancy

PURPOSE

In this study, we aimed to assess the distribution of genetic abnormalities leading to termination of pregnancy and its fluctuation during the past 8 years in light of those technical advances.

METHODS

Our cohort consisted of all pregnant women who underwent termination of pregnancy because of genetic aberrations in their fetuses from January 2010 through April 2018 in our medical center. The information that was gathered included: maternal age, results of the nuchal scan, results of the first- and second-trimester biochemical screening, ultrasonographic findings, reasons for conducting a genetic evaluation, gestational age at which termination of pregnancy was carried out, and the type of genetic aberration.

RESULTS

816 women underwent termination of pregnancy at our institution due to genetic aberrations, most of them because of positive biochemical screening (n = 297, 36%) or because of maternal anxiety (n = 283, 35%). Findings in chromosomal microarray led to termination of pregnancy in 100 women (100/816, 12%). Chromosomal microarray had been performed due to maternal choice and not because of accepted medical indications among most of the women who underwent termination of pregnancy due to findings on chromosomal microarray (69/100, 69%).

CONCLUSION

Performing chromosomal microarray on a structurally normal fetus and identifying abnormal copy number variants may give the parents enough information for deciding on the further course of the pregnancy.

Performance of semiconductor sequencing platform for non-invasive prenatal genetic screening for fetal aneuploidy: results from a multicenter prospective cohort study in a clinical setting

OBJECTIVE

To validate and evaluate the performance metrics of the high-throughput semiconductor sequencing platform, Ion Proton®, in non-invasive prenatal genetic screening (NIPS) for common fetal aneuploidies in a clinical setting.

METHODS

This prospective cohort study included 2505 pregnant women from eight academic genetics laboratories (695 high risk for trisomy 21 (risk ≥ 1/250) pregnancies in a validation study, and 1810 such pregnancies, without ultrasound anomalies, in a real-life NIPS clinical setting). Outcome was available for all cases in the validation cohort and for 521 in the clinical cohort. Cell-free DNA from plasma samples was sequenced using the Ion Proton sequencer, and sequencing data were analyzed using the open-access software, WISECONDOR. Performance metrics for detection of trisomies 21, 18 and 13 were calculated based on either fetal karyotype result or clinical data collected at birth. We also evaluated the failure rate and compared three methods of fetal fraction quantification (RASSF1A assay, and DEFRAG and SANEFALCON software).

RESULTS

Results from both cohorts were consistent and their gestational age was not significantly different so their data were combined to increase the sample size for analysis. Sensitivities and specificities, respectively, were as follows: for trisomy 21, 98.3% (95% CI, 93.5-99.7%) and 99.9% (95% CI, 99.4-100%); for trisomy 18, 96.7% (95% CI, 80.9-99.8%) and 100% (95% CI, 99.6-100%); and for trisomy 13, 94.1% (95% CI, 69.2-99.7%) and 100% (95% CI, 99.6-100%). Our failure rate was 1.2% initially and as low as 0.6% after retesting some of the failed samples. Fetal fraction estimation by the RASSF1A assay was consistent with DEFRAG results, and both were adequate for routine diagnosis.

CONCLUSIONS

We describe one of the largest studies evaluating Ion Proton-based NIPS and the first clinical study reporting pregnancy outcome in a large series of patients. This platform is highly efficient in detecting the three most common trisomies. Our protocol is robust and can be implemented easily in any medical genetics laboratory. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.