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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., (© 2021 Nordic Federation of Societies of Obstetrics and Gynecology (NFOG). Published by John Wiley & Sons Ltd.)

Objective: To evaluate time of diagnosis of 22q11.2 deletion and 22q11.2 duplication as well as trisomies 21, 13, and 18 before and after introduction of a prenatal screening program including combined first-trimester screening (cFTS) for the trisomies in Denmark in 2004., Method: Cross-sectional, population-based register study employing The Danish Cytogenetic Central Register. Proportions of cases diagnosed 1998-2004 and 2005-2017 were compared before 14 +0 and 22 +0 weeks and birth (prenatal cases) or up to 1 or 10 years of age (postnatal cases)., Results: In total, 4562 cases were included. From 1998-2004 to 2005-2017, the proportion of 22q11.2 deletion cases identified prenatally increased from 4.3% (95% CI: 0.9-12.0%) to 27.3% (21.2-34.0%), while for 22q11.2 duplication an increase from 0/6 to 26/87 (prenatal cases/all cases) was observed. Similarly, proportions of trisomies 21, 13, and 18 detected before birth increased. A greater proportion of the studied conditions was identified earlier in pregnancy, but not generally earlier in the postnatal course., Conclusion: Proportions of 22q11.2 deletion and 22q11.2 duplication identified prenatally increased after introduction of a prenatal screening program not aimed specifically to identify these conditions,. A greater proportion of all cases were detected earlier in pregnancy, but not earlier postnatally, following introduction of screening., (© 2020 John Wiley & Sons Ltd.)

Aim: To examine the performance of the combined First Trimester Screening (cFTS) algorithm when outliers of 4 risk parameters (maternal age, nuchal translucency (NT) thickness, PAPP-A and β-hCG) were included in the classification of "high-risk"., Methods: A retrospective analysis of singleton pregnancies undergoing cFTS between 2008 and 2011 in Denmark. Abnormal karyotypes were classified as trisomy 21 (T21), trisomy 13 (T13) and trisomy 18 (T18), sex chromosome aberrations and atypical abnormal karyotypes., Results: cFTS was completed in 193,638 pregnancies. In 10,205 (5.3%) cases, cytogenetic or molecular analysis was performed pre- or postnatally. An abnormal karyotype was seen in 1,122 (11.0%). The algorithm identified 87% of T21, 80% of T13, 75% of T18, 79% of sex chromosome aberrations and 35% of atypical abnormal karyotypes. Additional classification of a single risk parameter outlier (low PAPP-A or free β-hCG (< 0.2 MoMs), high β-hCG (≥5.0 MoMs), maternal age ≥45 years or NT ≥3.5 mm) as being at high-risk would have improved detection rates to 88, 80, 81, 81 and 37% respectively. The screen positive rate increased from 4.4 to 4.8%., Discussion: Addition of outliers of the 4 parameters used in cFTS algorithm will lead to a statistically significant increase in detection rates for chromosomal abnormality., (© 2018 S. Karger AG, Basel.)