Efficiency of non-invasive prenatal screening in pregnant women at advanced maternal age

Clinical value of screening prenatal ultrasound combined with chromosomal microarrays in prenatal diagnosis of chromosomal abnormalities

OBJECTIVE

To evaluate the clinical value of ultrasound findings in the screening of fetal chromosomal abnormalities and the analysis of risk factors for chromosome microarray analysis (CMA) abnormalities.

METHODS

We retrospectively analyzed the datasets of 15,899 pregnant women who underwent prenatal evaluations at Affiliated Maternity and Child Health Care Hospital of Nantong University between August 2018 and December 2022. Everyone underwent ultrasound screening, and those with abnormal findings underwent CMA to identify chromosomal abnormalities.

RESULTS

The detection rates for isolated ultrasound anomalies and combined ultrasound and CMA anomalies were 11.81% (1877/15,899) and 2.40% (381/15,899), respectively. Among all ultrasound abnormalities, detection rates for isolated ultrasound soft marker anomalies, isolated structural abnormalities, and both ultrasound soft marker anomalies with structural abnormalities were 82.91% (1872/2258), 15.99% (361/2258), and 1.11% (25/2258), respectively. The detection rate of abnormal chromosomes in pregnant women with abnormal ultrasound results was 16.87% (381/2258). The detection rates were 13.33% in cases with two or more ultrasound soft markers anomalies, 47.37% for two or more structural anomalies, and 48.00% for concomitant ultrasound soft marker and structural anomalies.

CONCLUSIONS

Enhanced detection rates of chromosomal anomalies in fetal malformations are achieved with specific ultrasound findings (NT thickening, cardiovascular abnormalities, and multiple soft markers) or when combined with high-risk factors (advanced maternal age, familial history, parental chromosomal anomalies, etc.). When the maternal age is over 35 and with ≥2 ultrasound soft marker anomalies accompanied with any high-risk factors, CMA testing can aid in the diagnosis of prenatal chromosomal abnormalities.

Spatiotemporal trends and geographic disparities in spatial accessibility to maternal and child health services in Nanning, China: impact of two-child policies

BACKGROUND

China's family planning policies have experienced stages of one-child policy, partial two-child policy, and universal two-child policy. However, the impact of these policy shifts on the spatial accessibility to maternal and child health (MCH) services for women and children remains uncertain. This study aimed to evaluate the spatiotemporal trends and geographic disparities in spatial accessibility to MCH services in the context of two-child polices.

METHODS

This study was conducted in Nanning prefecture, China, from 2013 to 2019. Data on the transportation networks, MCH institutes, the annual number of newborns, and the annual number of pregnant women in Nanning prefecture were collected. Gaussian two-step floating catchment area (Ga2SFCA) method was employed to measure the spatial accessibility to MCH services at county, township, and village levels. Temporal trends in spatial accessibility were analyzed using Joinpoint regression analysis. Geographic disparities in spatial accessibility were identified using geographic information system (GIS) mapping techniques.

RESULTS

Overall, the spatial accessibility to MCH services showed an upward trend from 2013 to 2019 at county, town, and village levels, with the average annual percent change (AAPC) being 5.04, 4.73, and 5.39, respectively. Specifically, the spatial accessibility experienced a slight downward trend during the period of partial two-child policy for both parents only children (i.e., 2013-2014), a slight upward trend during the period of partial two-child policy for either parent only child (i.e., 2014-2016) and the early stages of universal two-child policy (i.e., 2016-2018), and a large upward trend in the later stages of universal two-child policy (i.e., 2018-2019). Spatial accessibility to MCH services gradually decreased from central urban areas to surrounding rural areas. Regions with low spatial accessibility were predominantly located in remote rural areas.

CONCLUSION

With the gradual opening of the two-child policies, the spatial accessibility to MCH services for women and children has generally improved. However, significant geographic disparities have persisted throughout the stages of the two-child policies. Comprehensive measures should be considered to improve equity in MCH services for women and children.

Prospective prenatal cell-free DNA screening for genetic conditions of heterogenous etiologies

Prenatal cell-free DNA (cfDNA) screening uses extracellular fetal DNA circulating in the peripheral blood of pregnant women to detect prevalent fetal chromosomal anomalies. However, numerous severe conditions with underlying single-gene defects are not included in current prenatal cfDNA screening. In this prospective, multicenter and observational study, pregnant women at elevated risk for fetal genetic conditions were enrolled for a cfDNA screening test based on coordinative allele-aware target enrichment sequencing. This test encompasses the following three of the most frequent pathogenic genetic variations: aneuploidies, microdeletions and monogenic variants. The cfDNA screening results were compared to invasive prenatal or postnatal diagnostic test results for 1,090 qualified participants. The comprehensive cfDNA screening detected a genetic alteration in 135 pregnancies with 98.5% sensitivity and 99.3% specificity relative to standard diagnostics. Of 876 fetuses with suspected structural anomalies on ultrasound examination, comprehensive cfDNA screening identified 55 (56.1%) aneuploidies, 6 (6.1%) microdeletions and 37 (37.8%) single-gene pathogenic variants. The inclusion of targeted monogenic conditions alongside chromosomal aberrations led to a 60.7% increase (from 61 to 98) in the detection rate. Overall, these data provide preliminary evidence that a comprehensive cfDNA screening test can accurately identify fetal pathogenic variants at both the chromosome and single-gene levels in high-risk pregnancies through a noninvasive approach, which has the potential to improve prenatal evaluation of fetal risks for severe genetic conditions arising from heterogenous molecular etiologies. ClinicalTrials.gov registration: ChiCTR2100045739 .

Noninvasive Prenatal Screening for Common Fetal Aneuploidies Using Single-Molecule Sequencing

Amplification biases caused by next-generation sequencing (NGS) for noninvasive prenatal screening (NIPS) may be reduced using single-molecule sequencing (SMS), during which PCR is omitted. Therefore, the performance of SMS-based NIPS was evaluated. We used SMS-based NIPS to screen for common fetal aneuploidies in 477 pregnant women. The sensitivity, specificity, positive predictive value, and negative predictive value were estimated. The GC-induced bias was compared between the SMS- and NGS-based NIPS methods. Notably, a sensitivity of 100% was achieved for fetal trisomy 13 (T13), trisomy 18 (T18), and trisomy 21 (T21). The positive predictive value was 46.15% for T13, 96.77% for T18, and 99.07% for T21. The overall specificity was 100% (334/334). Compared with NGS, SMS (without PCR) had less GC bias, a better distinction between T21 or T18 and euploidies, and better diagnostic performance. Overall, our results suggest that SMS improves the performance of NIPS for common fetal aneuploidies by reducing the GC bias introduced during library preparation and sequencing.

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.

Study on the Clinical Value of Noninvasive Prenatal Testing in Screening the Chromosomal Abnormalities of the Fetus in the Elderly Pregnant Women

Introduction

To explore the clinical value of noninvasive prenatal testing (NIPT) in screening the chromosomal abnormalities of the fetus in the elderly pregnant women.

Materials and Methods

Between January 2020 and December 2021, 1949 elderly pregnant women underwent NIPT in our hospital. At the same time, 236 elderly pregnant women received invasive prenatal diagnosis, and the pregnancy outcomes were followed-up.

Results

When NIPT was used for prenatal screening of fetal chromosomal aneuploidy, its diagnostic coincidence rate for trisomy 21 was the highest, with a coincidence rate of 90.00%, and the diagnostic coincidence rate for other chromosomal abnormalities was the lowest, only 22.22%. The sensitivity, specificity, positive predictive rate, and negative predictive rate for T21 by NIPT were 100%, 99.97%, 94.28%, and 100%; for T18 were 100%, 99.92%, 72.22%, and 100%, respectively; and for T13 were 100%, 99.95%, 50%, and 100%, respectively. Patients with high risks according to NIPT results further received invasive prenatal diagnosis, and 18 cases were excluded from the follow-up. For the remaining 1933 cases in the NIPT group, there was an incidence of 2.28% of adverse pregnancy outcomes. For the remaining 234 cases in the Amniocentesis group, there was an incidence of 1.28% of adverse pregnancy outcomes. There was no significant difference between the two groups (P > 0.05). The diagnostic rate of fetal chromosomal abnormalities in pregnant women under 40 years old was about 0.39-0.79%; however, the risk for people over 40 is relatively high at 1.32-4.44%.

Conclusion

The noninvasive prenatal screening of fetal DNA in the second trimester of pregnancy for elderly pregnant women has high application value in the prediction of pregnancy outcome. The high risk of pregnancy can be determined by detecting trisomy 21, 18, and 13 syndromes, and the probability of adverse pregnancy outcome increases.

Genome-Wide Copy Number Variant and High-Throughput Transcriptomics Analyses of Placental Tissues Underscore Persisting Child Susceptibility in At-Risk Pregnancies Cleared in Standard Genetic Testing

Several studies have shown that children from pregnancies with estimated first-trimester risk based on fetal nuchal translucency thickness and abnormal maternal serum pregnancy protein and hormone levels maintain a higher likelihood of adverse outcomes, even if initial testing for known genetic conditions is negative. We used the Finnish InTraUterine cohort (ITU), which is a comprehensively characterized perinatal cohort consisting of 943 mothers and their babies followed throughout pregnancy and 18 months postnatally, including mothers shortlisted for prenatal genetic testing but cleared for major aneuploidies (cases: n = 544, 57.7%) and control pregnancies (n = 399, 42.3%). Using genome-wide genotyping and RNA sequencing of first-trimester and term placental tissue, combined with medical information from registry data and maternal self-report data, we investigated potential negative medical outcomes and genetic susceptibility to disease and their correlates in placenta gene expression. Case mothers did not present with higher levels of depression, perceived stress, or anxiety during pregnancy. Case children were significantly diagnosed more often with congenital malformations of the circulatory system (4.12 (95% CI [1.22−13.93]) higher hazard) and presented with significantly more copy number duplications as compared to controls (burden analysis, based on all copy number variants (CNVs) with at most 10% frequency, 823 called duplications in 297 cases versus 626 called duplications in 277 controls, p = 0.01). Fifteen genes showed differential gene expression (FDR < 0.1) in association with congenital malformations in first-trimester but not term placenta. These were significantly enriched for genes associated with placental dysfunction. In spite of normal routine follow-up prenatal testing results in early pregnancy, case children presented with an increased likelihood of negative outcomes, which should prompt vigilance in follow-up during pregnancy and after birth.

A Critical Evaluation of Validation and Clinical Experience Studies in Non-Invasive Prenatal Testing for Trisomies 21, 18, and 13 and Monosomy X

Non-invasive prenatal testing (NIPT) for trisomies 21, 18, 13 and monosomy X is widely utilized with massively parallel shotgun sequencing (MPSS), digital analysis of selected regions (DANSR), and single nucleotide polymorphism (SNP) analyses being the most widely reported methods. We searched the literature to find all NIPT clinical validation and clinical experience studies between January 2011 and January 2022. Meta-analyses were performed using bivariate random-effects and univariate regression models for estimating summary performance measures across studies. Bivariate meta-regression was performed to explore the influence of testing method and study design. Subgroup and sensitivity analyses evaluated factors that may have led to heterogeneity. Based on 55 validation studies, the detection rate (DR) was significantly higher for retrospective studies, while the false positive rate (FPR) was significantly lower for prospective studies. Comparing the performance of NIPT methods for trisomies 21, 18, and 13 combined, the SNP method had a higher DR and lower FPR than other methods, significantly so for MPSS, though not for DANSR. The performance of the different methods in the 84 clinical experience studies was consistent with validation studies. Clinical positive predictive values of all NIPT methods improved over the last decade. We conclude that all NIPT methods are highly effective for fetal aneuploidy screening, with performance differences across methodologies.

Association between cesarean section rate and maternal age in twin pregnancies

OBJECTIVES

To evaluate the effect of maternal age to the cesarean section rate of twin pregnancies in late preterm and term gestation.

METHODS

A retrospective study was performed on twin pregnancies delivered at Seoul National University Bundang Hospital from June 2003 to December 2020. Preterm births before 34 weeks of gestation were excluded, and only live births were analyzed. The patients were classified into four groups according to maternal age (<30, 30-34, 35-39, and ≥40 years). The primary outcome was the rate of cesarean section.

RESULTS

The median value of maternal body mass index, the rate of assisted reproductive technology, dichorionic twin pregnancy, preeclampsia, and gestational diabetes increased significantly according to the maternal age group (all p<0.05). Among a total of 2,075 twin pregnancies, the rates of cesarean section were 65, 74, 80, and 95% for groups with maternal age under 30, 30-34, 35-39, and ≥40 years, respectively (p<0.001). The cesarean section rates after a trial of labor were 22, 22, 28, and 63%, respectively (p=0.032). Maternal old age was an independent risk factor for cesarean section after a trial of labor in both nulliparous and multiparous women after adjusting for confounding factors.

CONCLUSIONS

The rate of cesarean section in twin pregnancies significantly increased as maternal age increased, even in multiparous women.