Danish Fetal Medicine Database Research Articles

Atypicality index as an add-on to combined first-trimester screening for chromosomal aberrations.

To compute a set of atypicality indices based on combined first-trimester screening (cFTS) markers and second-trimester estimated fetal weight (EFW), and to demonstrate their potential in identifying pregnancies at reduced or increased risk of chromosomal aberrations following a low-risk cFTS result. The atypicality index quantifies the unusualness of an individual set of measurements relative to a reference distribution and can be computed from any variables or measurements available. A score of 0% on the atypicality index represents the most typical profiles, while a score of 100% indicates the highest level of atypicality. From the Danish Fetal Medicine Database, we retrieved data on all pregnant women seen for cFTS in the Central Denmark Region between January 2008 and December 2018. All pregnancies with a cytogenetic or molecular analysis obtained prenatally, postnatally or following pregnancy loss or termination were identified. A first-trimester atypicality index (AcFTS) was computed based on nuchal translucency (NT) thickness, maternal serum free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A). Furthermore, a second-trimester index (AcFTS + EFW) was computed from cFTS markers and EFW from a routine second-trimester anomaly scan. All pregnancies were stratified into subgroups based on their atypicality levels and their cFTS risk estimates. The risk of chromosomal aberrations in each subgroup was then compared with the overall prevalence, and a graphical presentation of the multivariate measurement profiles was developed. We retrieved data on 145 955 singleton pregnancies, of which 9824 (6.7%) were genetically examined. Overall, 1 in 122 (0.82% (95% CI, 0.77-0.87%)) of all pregnancies seen for cFTS were affected by a fetal chromosomal aberration, and in screen-negative pregnancies (cFTS trisomy 21 risk < 1 in 100 and/or trisomy 18/13 risk < 1 in 50), 0.41% (95% CI, 0.38-0.44%) were affected. In screen-negative pregnancies with a typical first-trimester profile (AcFTS < 80%), the risk of chromosomal aberrations was significantly reduced (0.28%) compared with the overall risk. The risk of chromosomal aberrations increased with higher atypicality index to 0.49% (AcFTS [80-90%)), 1.52% (AcFTS [90-99%)) and 4.44% (AcFTS ≥ 99%) and was significantly increased in the two most atypical subgroups. The same applied for the second-trimester atypicality index, with risks of chromosomal aberrations of 0.76% and 4.16% in the two most atypical subgroups (AcFTS + EFW [90-99%) and AcFTS + EFW ≥ 99%, respectively). As an add-on to cFTS, the atypicality index identifies women with typical measurement profiles, which may provide reassurance, whereas atypical profiles may warrant specialist referral and further investigation. In pregnancies identified as low risk on cFTS but with a highly atypical distribution of NT, PAPP-A and β-hCG, the risk of a chromosomal aberration is substantially increased. The atypicality index optimizes the interpretation of pre-existing prenatal screening profiles and is not limited to cFTS markers or EFW. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Combined first-trimester screening and invasive diagnostics for atypical chromosomal aberrations: Danish nationwide data on prenatal profiles and detection compared with NIPT.

To examine the prenatal profiles of pregnancies affected by an atypical chromosomal aberration, focusing on pathogenic copy number variants (pCNVs). Further, we wanted to quantify the performance of combined first-trimester screening (cFTS) and a second-trimester anomaly scan in detecting these conditions. Finally, we aimed to estimate the consequences of a policy of using non-invasive prenatal testing (NIPT) rather than invasive testing with chromosomal microarray (CMA) to manage pregnancies identified as high risk from cFTS. A retrospective review of the Danish fetal medicine database identified all pregnant women who had cFTS and a trisomy 21 risk-assessment between January 1, 2008, and December 31, 2018. Chromosomal aberrations diagnosed prenatally, postnatally, or from fetal tissue following pregnancy loss or termination of pregnancy (TOP) were identified. Chromosomal aberrations were grouped into one of six categories: 1) Triploidy; 2) Common trisomies (trisomies 21, 18, and 13); 3) Monosomy X; 4) Other sex chromosome aberrations (SCAs); 5) pCNVs; and 6) Rare autosomal trisomies (RATs) and mosaicisms. The prevalence of each aberration-category was stratified by the individual cFTS markers and risk estimate, and the size of each pCNV diagnosed from CMA was calculated. We included data on 565,708 pregnancies of which 3,982 were diagnosed with a fetal chromosomal aberration (0.70%). cFTS performed well in identifying triploidies (86%), monosomy X (92%), atypical SCAs (58%), and RATs and mosaicisms (70%). pCNVs comprised 28% (n=1,091) of the chromosomal aberrations diagnosed overall, and the prevalence increased during the study period with more prenatal chromosomal microarray analysis being performed. In pregnancies with maternal age <30 years, NT <95th percentile, PAPP-A MoM ≥ 1, or trisomy 21 risk ≥1 in 1000, the prevalence of pCNVs significantly exceeded the prevalence of trisomies 21, 18, and 13. Pregnancies affected by a pCNV had significantly increased nuchal translucency thickness (NT) and decreased maternal biomarkers pregnancy associated plasma protein-A (PAPP-A) and β-human chorionic gonadotropin (β-hCG) compared with unaffected pregnancies. However, only 23% of these pregnancies screened positive from cFTS and 51% were not detected until after birth. Amongst high-risk pregnancies diagnosed with a chromosomal aberration, pCNVs comprised 14% and when other atypical aberrations were considered, conventional NIPT (screening for trisomies 21, 18, and 13, and monosomy X) would miss 28% of all pathogenic aberrations diagnosed following a high-risk cFTS result. Thus, 1 in 26 pregnancies at high-risk following cFTS would be affected by a chromosomal aberration despite a normal conventional NIPT result. In a contingent screening model with NIPT provided for the "intermediate" risk group (T21 risk of 1 in 100-300), 50% of the aberrations would be missed. In our cohort, 80% of the pCNVs diagnosed were <5Mb and therefore not detectable using current forms of "genome wide" NIPT. As a by-product to screening for trisomies 21, 18, and 13, most triploidies and the majority of atypical SCAs, RATs, and mosaicisms are detected before birth. However, only 23% of pCNVs are high-risk from cFTS and only half are diagnosed before birth. Replacing invasive testing with NIPT for high-risk pregnancies would substantially decrease the first-trimester detection of pathogenic chromosomal anomalies. This article is protected by copyright. All rights reserved.

Quadruplet pregnancy outcome with and without fetal reduction: Danish national cohort study (2008-2018) and comparison with dichorionic twins.

To perform a nationwide study of quadrichorionic quadriamniotic (QCQA) quadruplet pregnancies and to compare the pregnancy outcome in those undergoing fetal reduction with non-reduced quadruplets and dichorionic diamniotic (DCDA) twin pregnancies from the same time period. This was a retrospective Danish national register-based study performed using data from the national Danish Fetal Medicine Database, which included all QCQA quadruplets and all non-reduced DCDA twin pregnancies with an estimated due date between 2008 and 2018. The primary outcome measure was a composite of adverse pregnancy outcomes, including pregnancy loss or intrauterine death of one or more fetuses. Secondary outcomes included gestational age at delivery, the number of liveborn children, preterm delivery before 28, 32 and 37 gestational weeks and birth weight. Data on pregnancy complications and baseline characteristics were also recorded. Outcomes were compared between reduced and non-reduced quadruplet pregnancies, and between DCDA pregnancies and quadruplet pregnancies reduced to twins. A systematic literature search was performed to describe and compare previous results with our findings. Included in the study were 33 QCQA quadruplet pregnancies, including three (9.1%) non-reduced pregnancies, 28 (84.8%) that were reduced to twin pregnancy and fewer than three (6.1%) that were reduced to singleton pregnancy, as well as 9563 DCDA twin pregnancies. Overall, the rate of adverse pregnancy outcome was highest in non-reduced quadruplets (66.7%); it was 50% in quadruplets reduced to singletons and 10.7% in quadruplets reduced to twins. The proportion of liveborn infants overall was 91.1% of the total number expected to be liveborn in quadruplet pregnancies reduced to twins. This was statistically significantly different from 97.6% in non-reduced dichorionic twins (P = 0.004), and considerably higher than 58.3% in non-reduced quadruplets. The rates of preterm delivery < 28, < 32 and < 37 weeks were decreased in quadruplets reduced to twins compared with those in non-reduced quadruplet pregnancies. Quadruplets reduced to twins did not achieve equivalent pregnancy outcomes to those of DCDA twins. This national study of QCQA quadruplets has shown that multifetal pregnancy reduction improves pregnancy outcome, including a decreased rate of preterm delivery and higher proportion of liveborn children. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Use of cell-free non-invasive prenatal testing in pregnancies affected by placental mosaicism.

To evaluate cell-free non-invasive prenatal testing (cfNIPT) in pregnancies affected by mosaicism. We assessed paired cfNIPT and chorionic villus sample (CVS) results from the same pregnancies in a case series of mosaicism detected in Central and North Denmark Regions from April 2014 to September 2018. Indications for the clinically obtained CVS, pregnancy markers and outcome were retrieved from The Danish Fetal Medicine Database. Mosaicisms in CVS involved common aneuploidy, n=14; sex chromosomal aneuploidies, n=14; rare autosomal trisomies (RATs), n=16 and copy number variants (CNVs) >5Mb, n=9. Overall, 24/53 (45.3%; CI 95%: 31.8%-59.4%) of cases with mosaicism were detected by cfNIPT; highest for RATs (56%) and lowest for CNVs (22%). CfNIPT more commonly detected high-level than low-level mosaic cases (p=0.000). CfNIPT detected 7/16 (43.8%; CI 95%: 21%-69%) clinically significant mosaic cases, either true fetal mosaicism or confined placental mosaicisms with adverse pregnancy outcome. There was a trend toward a higher risk for adverse outcome in pregnancies where mosaicism was detected by cfNIPT compared to pregnancies where mosaicism was not detected by cfNIPT (p=0.31). CfNIPT has a low detection rate of mosaicism, including pregnancies with clinically significant mosaicism. However, abnormal cfNIPT results may be a predictor of adverse pregnancy outcomes.

Decoding 22q11.2: prenatal profiling and first-trimester risk assessment in Danish nationwide cohort.

To examine the distribution of nuchal translucency thickness (NT), free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) in pregnancies with a fetal 22q11.2 aberration. Furthermore, the performance of combined first-trimester screening (cFTS) and a new risk algorithm targeting 22q11.2 deletions in detecting affected pregnancies was evaluated. Finally, prenatal malformations and pregnancy outcome were assessed. This was a nationwide registry-based cohort study of all pregnancies that underwent prenatal screening with a due date between January 2008 and December 2018 in Denmark. All cases with a fetal 22q11.2 deletion or duplication (hg19 chr22:18.9mio-25.0mio) diagnosed pre- or postnatally or following pregnancy loss or termination of pregnancy were retrieved from the Danish Cytogenetic Central Register and linked with pregnancy data from the Danish Fetal Medicine Database. Fetal and maternal characteristics, including cFTS results and pregnancy outcome, of pregnancies with any 22q11.2 deletion or duplication (LCR22-A to -H) and pregnancies with a classic deletion or duplication (LCR22-A to -D) diagnosed by chromosomal microarray were compared with those of a chromosomally normal reference group. A risk algorithm was developed for assessing patient-specific risks for classic 22q11.2 deletions based on NT, PAPP-A and β-hCG. Detection rates and false-positive rates at different risk cut-offs were calculated. We included data on 143 pregnancies with a fetal 22q11.2 aberration, of which 97 were deletions (54 classic) and 46 were duplications (32 classic). NT was significantly increased in fetuses with a classic deletion (mean, 1.89 mm), those with any deletion (mean, 1.78 mm) and those with any duplication (mean, 1.86 mm) compared to the reference group (mean, 1.65 mm). β-hCG multiples of the median (MoM) was decreased in all 22q11.2 subgroups compared with the reference group (mean, 1.02) and reached significance in pregnancies with a classic deletion and those with any deletion (mean, 0.77 and 0.71, respectively). PAPP-A MoM was significantly decreased in pregnancies with a classic duplication and those with any duplication (mean, 0.57 and 0.63, respectively), and was significantly increased in pregnancies with a classic deletion and those with any deletion (mean, 1.34 and 1.16, respectively), compared to reference pregnancies (mean, 1.01). The screen-positive rate by cFTS was significantly increased in pregnancies with a classic deletion (13.7%), any deletion (12.5%), a classic duplication (46.9%) or any duplication (37.8%) compared to the reference group (4.5%). A risk algorithm targeting classic 22q11.2 deletions more than doubled the prenatal detection rate of classic 22q11.2 deletions, but with a substantial increase in the false-positive rate. Structural malformations were detected in 41%, 35%, 17% and 25% of the pregnancies with a classic deletion, any deletion, classic duplication or any duplication, respectively. Pregnancy loss occurred in 40% of pregnancies with a classic deletion and 5% of those with a classic duplication diagnosed prenatally or following pregnancy loss. The distribution of cFTS markers in pregnancies with a classic 22q11.2 duplication resembles that of the common trisomies, with decreased levels of PAPP-A. However, classic 22q11.2 deletions are associated with increased levels of PAPP-A, which likely limits early prenatal detection using the current cFTS risk algorithm. The scope for improving early detection of classic 22q11.2 deletions using targeted risk algorithms based on NT, PAPP-A and β-hCG is limited. This demonstrates the capability, but also the limitations, of cFTS markers in detecting atypical chromosomal anomalies, which is important knowledge when designing new prenatal screening programs. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Prevalence and detection rate of major congenital heart disease in twin pregnancies in Denmark.

To investigate the national prevalence and prenatal detection rate (DR) of major congenital heart disease (mCHD) in twin pregnancies without twin-to-twin transfusion syndrome (TTTS)-associated CHD in a Danish population following a standardized prenatal screening program. This was a national registry-based study of data collected prospectively over a 10-year period. In Denmark, all women with a twin pregnancy are offered standardized screening and surveillance programs in addition to first- and second-trimester screening for aneuploidies and malformation, respectively: monochorionic (MC) twins every 2 weeks from gestational week 15 and dichorionic (DC) twins every 4 weeks from week 18. The data were retrieved from the Danish Fetal Medicine Database and included all twin pregnancies from 2009-2018, in which at least one fetus had a pre- and/or postnatal mCHD diagnosis. mCHD was defined as CHD requiring surgery within the first year of life, excluding ventricular septal defects. All pregnancy data were pre- and postnatally validated in the local patient files at the four tertiary centers covering the entire country. A total of 60 cases from 59 twin pregnancies were included. The prevalence of mCHD was 4.6 (95% CI, 3.5-6.0) per 1000 twin pregnancies (1.9 (95% CI, 1.3-2.5) per 1000 live births). The prevalences for DC and MC were 3.6 (95%CI, 2.6-5.0) and 9.2 (95%CI, 5.8-13.7) per 1000 twin pregnancies, respectively. The national prenatal DR of mCHD in twin pregnancies for the entire period was 68.3%. The highest DRs were in cases with univentricular hearts (100%) and the lowest with aortopulmonary window, total anomalous pulmonary venous return, Ebstein's anomaly, aortic valve stenosis and coarctation of the aorta (0-25%). Mothers of children with prenatally undetected mCHD had a significantly higher body mass index (BMI) compared to mothers of children with a prenatally detected mCHD (median, 27 kg/m2 and 23 kg/m2 , respectively; P = 0.02). The prevalence of mCHD in twins was 4.6 per 1000 pregnancies and was higher in MC than DC pregnancies. The prenatal DR of mCHD in twin pregnancies was 68.3%. Maternal BMI was higher in cases of prenatally undetected mCHD. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Risk of adverse pregnancy outcome in isolated single umbilical artery diagnosed at the mid-trimester anomaly scan: a large Danish retrospective cohort study

Objective To examine the association of isolated single umbilical artery (iSUA) confirmed at the mid-trimester anomaly scan and adverse pregnancy outcome and congenital malformations with up to 10 years postnatal follow up. Methods This retrospective cohort study included 116,501 singleton pregnancies consecutively enrolled in first trimester screening for aneuploidies and mid-trimester anomaly scan at three University Hospitals in the Capital Region of Copenhagen, Denmark. Data from the Danish Fetal Medicine Database (2008–2017) were verified by manually scrutinizing pre- and postnatal records. The main outcomes of interest were intrauterine fetal demise (IUFD), small for gestational age (SGA), preterm delivery, cesarean section and unrecognized pre- and postnatal congenital malformations. Results In total, 775 pregnancies with iSUA were identified. Isolated SUA were associated with a significantly increased risk of IUFD (OR 4.16, 95% CI 2.06–8.44), SGA < 3rd centile (aOR 2.41, 95% 1.85–3.14) and SGA < 10th centile (aOR 1.84, 95% CI 1.53–2.21), but not with preterm delivery or cesarean section. The laterality of the missing artery was not associated with SGA. In total, 4.3% of pregnancies with iSUA had unrecognized congenital malformations. 1.5% with iSUA had congenital cardiovascular malformations, which were considered minor. Conclusion Isolated SUA is associated with IUFD and SGA, supporting surveillance during third trimester. If, during the mid-trimester scan, the sonographer achieves thorough, extended cardiac views and finds no additional malformation other than SUA, fetal echocardiography seems not to be needed.

First-trimester biomarkers and ultrasound biometries in relation to growth discordance in monochorionic diamniotic twins

Objective The aim of this study was to investigate the association and predictive value between intertwin discordance in first trimester biometries crown-rump length (CRL) and nuchal translucency (NT), and the first trimester biochemical markers PAPP-A and free β-hCG in relation to birth weight discordance (BWD) ≥25% in monochorionic diamniotic (MCDA) twin pregnancies. Methods First trimester screening information and pregnancy outcome data on MCDA twin pregnancies with delivery from July 2008 to July 2017 were retrieved from the Danish Fetal Medicine Database. CRL discordance was divided into: <10% (reference group) and ≥10%. NT discordance was divided into: <20% (reference group) and ≥20%. The twin pregnancies were classified according to BWD into the following groups: <10% (reference group), 10–24.9%, and ≥25% including cases undergoing umbilical cord occlusion due to selective fetal growth restriction (sFGR). The twin pregnancies with the most severe BWD (BWD ≥25%) were subdivided into three groups including cases with only one growth-restricted (<10th centile) infant defined as sFGR, and cases where both twins were <10th centile. Median multiples of the median (MoM) values of PAPP-A and free ß-hCG were compared with the group with BWD <10% using the Wilcoxon two-sample test. The ability of CRL discordance and NT discordance to predict BWD ≥25% was examined by the area under the receiver operator characteristic (ROC) curve. Results A total of 762 MCDA pregnancies were included. The proportion of pregnancies with CRL discordance ≥10% and NT discordance ≥20% was significantly higher in the group with severe BWD discordance (27.0% vs. 4.7% (p < 0.001) and 40.9% vs. 23.9% (p = 0.001), respectively). When examining the three subgroups of severe BWD, we found a significantly higher percentage of pregnancies with CRL discordance ≥10% in the group where umbilical cord occlusion was performed (52.6% vs. 4.7% in the group with BWD <10% (p < 0.001)) and in the group of BWD ≥25% with sFGR (21.7% vs. 4.7% (p < 0.001)). Additionally, a significantly higher percentage of pregnancies with NT discordance ≥20% was found in the group where umbilical cord occlusion was performed (52.6% vs. 23.9% (p = 0.005)) and in the group with both twins <10th centile (66.7% vs. 23.9% (p = 0.003)). No statistically significant differences were found when comparing levels of PAPP-A and free β-hCG MoMs with the group with BWD <10%. In ROC curves, CRL discordance yielded an AUC for prediction of BWD ≥25% of 0.70 (95% CI 0.63–0.76), and for NT discordance AUC was 0.59 (95% CI 0.52–0.66)). OR for any BWD ≥ 25% was 6.7 (95% CI 3.8–12.0) for pregnancies with a CRL discordance ≥10% compared to pregnancies with a CRL discordance <10%. Conclusions This study shows that a discordance in CRL and NT in MCDA twins are both significantly associated with development of BWD. The most important predictor remains CRL discordance ≥10%, thereby suggesting the unequal growth pattern in many cases with BWD is evident already in the first trimester of the pregnancy. No association was found between first trimester biochemical markers and severe BWD.

Prevalence of chromosomal disorders in cases with congenital heart defect: registry-based study from Denmarkbetween 2008 and 2018.

To estimate the prevalence of chromosomal conditions in all fetuses and children with major congenital heart defect (CHD) in Denmark between 2008 and 2018. This was a national registry-based study including all singleton pregnancies with a prenatally or postnatally diagnosed major CHD usually requiring surgery within the first year after birth and a due date between July 2008 and December 2018 in Denmark. Data were retrieved from the Danish Fetal Medicine Database (DFMD) and the Danish Cytogenetic Central Register(DCCR) in October 2020. The DCCR contains information on all prenatal and postnatal genetic analyses, including karyotyping, chromosomal microarray, polymerase chain reaction, multiplex ligation-dependent probe amplification and fluorescence in-situ hybridization. All cases were reviewed by a clinical geneticist, and genetic changes were classified as pathogenic, likely pathogenic, variant of uncertain significance, likely benign or benign. Pathogenic and likely pathogenic variants were considered to be abnormal. Cases with CHD without any registered chromosomal analysis reported were considered genetically normal. Isolated CHD was defined as a case with major CHD without any other structural malformations detected prenatally or postnatally. Results are given as n (%). Comparisons between isolated and non-isolated cases were performed using logistic regression analysis, and data are presented as odds ratios (ORs) with 95% CIs. A total of 8482 cases with any cardiovascular diagnosis were retrieved from the DFMD. Twins (n = 112) and minor CHD cases (n = 6921) were excluded, resulting in 1449 cases with major CHD. Of the included cases, 918 (63.4%) underwent chromosomal analysis. An abnormal test result was found in 187 cases, giving a prevalence of a chromosomal condition of 12.9% (95% CI, 11.2-14.7%) among all cases with major CHD. The highest prevalence of a chromosomal condition was found in cases with pulmonary atresia with intact ventricular septum and those with truncus arteriosus (both 28.6%), while the lowest prevalence was found in cases with transposition of the great arteries(2.2%) and congenitally corrected transposition of the great arteries (0%). In isolated cases of transposition of the great arteries, the prevalence of a chromosomal condition was 0.6%. The overall OR for a chromosomal condition in non-isolated cases compared with isolated cases was 2.72 (95% CI, 1.90-3.88). We found an overall prevalence of a chromosomal condition of 12.9% among cases with major CHD in a national cohort with a high participation rate in first- and second-trimester screening, without employing whole genome and whole exome sequencing. The prevalence of a chromosomal condition varied considerably according to CHD diagnosis and presence of associated extracardiac malformations. These findings are important for prenatal counseling. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

National data on the early clinical use of non-invasive prenatal testing in public and private healthcare in Denmark 2013-2017.

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. 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. 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 19713 during the study period: 20% were NIPT analyses (n=3936) and 80% invasive procedures (n=15777). 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. 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.

Why we succeed and fail in detecting fetal growth restriction: A population-based study.

The objective of this study was to explore the association between detection of fetal growth restriction and maternal-, healthcare provider- and organizational factors. A historical, observational, multicentre study. All women who gave birth to a child with a birthweight <2.3rd centile from 1 September 2012 to 31 August 2015 in Zealand, Denmark, were included. The population was identified through the Danish Fetal Medicine Database. Medical charts were reviewed to obtain data regarding maternal characteristics and information on the healthcare professionals. Date of authorization for the midwives and obstetricians involved was extracted from the Danish Health Authorization Registry. Multivariable Cox regression models were used to identify predictors of antenatal detection of fetal growth restriction, and analyses were adjusted for hospital, body mass index, parity, the presence of at least one risk factor and experience of the first midwife, number of midwife visits, number of visits to a doctor, the experience of the consultant midwife or the educational level of the doctor, the number of scans and gaps in continuity of midwife-care. Antenatal detection was defined as an ultrasound estimated fetal weight <2.3rd centile (corresponding to -2 standard deviations) prior to delivery. Among 78 544 pregnancies, 3069 (3.9%) had a fetal growth restriction. Detection occurred in 31% of fetal growth-restricted pregnancies. Clinical experience (defined as years since graduation) of the first consultation midwife was positively associated with detection, with a hazard ratio [HR] of 1.15, 95% confidence interval [CI] 1.03-1.28), for every 10years of additional experience. The hazard of detection increased with the number of midwife consultations (HR 1.15, 95% CI 1.05-1.26) and with multiparity (HR 1.28, 95% CI 1.03-1.58). After adjusting for all covariates, an unexplained difference between hospitals (P=.01) remained. The low-risk nullipara may constitute an overlooked group of women at increased risk of antenatal non-detection of fetal growth restriction. Being screened by experienced midwives during early pregnancy and having access to multiple midwife consultations may improve future diagnosis.

Associations Between ADHD Medication Use in Pregnancy and Severe Malformations Based on Prenatal and Postnatal Diagnoses: A Danish Registry-Based Study.

Attention-deficit/hyperactivity disorder (ADHD) medications are increasingly used in pregnancy. Studies on the pregnancy safety of these medications that are restricted to live births may underestimate severe teratogenic effects that cause fetal demise or termination of pregnancy. The present study addresses this limitation by including data from both prenatal and postnatal diagnoses of major malformations. A nationwide registry-based study was conducted of 364,012 singleton pregnancies in Denmark from November 1, 2007, to February 1, 2014. Exposures to ADHD medication were obtained from redeemed prescriptions from the Danish Health Services Prescription Database. Outcome data included prenatally diagnosed malformations from the Danish Fetal Medicine Database and postnatally diagnosed malformations from the Danish National Patient Registry. The primary outcome was major malformations overall, and secondary outcomes were malformations of the central nervous system and cardiac malformations. The comparison group was pregnancies with no redeemed prescriptions for ADHD medication. We defined severe cardiac malformations (SCM) as concurrent diagnoses of a cardiac malformation with miscarriage, termination, stillbirth, postnatal death, or cardiac surgery within 1 year of birth. The prevalence of first-trimester exposure to ADHD medication increased during the study period from 0.05% in 2008 to 0.27% in 2013, with the majority (473/569) of the exposures being to methylphenidate. There were 5.1% malformations overall and 2.1% cardiac malformations among the exposed compared to 4.6% and 1.0%, respectively, among the unexposed. For methylphenidate, the adjusted prevalence ratios (PRs) were 1.04 (95% confidence interval [CI], 0.70-1.55) for malformations overall and 1.65 (95% CI, 0.89-3.05) for any cardiac malformations (number needed to harm [NNH] = 92), with septum defects in 10 out of 12 cases. The PR for ventricular septal defect was 2.74 (95% CI, 1.03-7.28) and for SCM, 2.59 (95% CI, 0.98-6.90). Exposure to methylphenidate was not associated with an increased risk of malformations overall in data that included information from both prenatal and postnatal diagnoses of major malformations. There was an increased risk of cardiac malformations with NNH of 92 based on 12 cases among the exposed. More data are needed on other types of ADHD medication.

Performance of first trimester screening for Trisomy 21 in twin pregnancies.

To assess the performance of the Danish first trimester screening program in twin pregnancies. Retrospective, nation-wide, cohort study with data collected from the Danish Fetal Medicine Database (DFMD) and The Danish Central Cytogenetic Registry (DCCR). The cohort included all women with twin pregnancies participating in the national first trimester screening program for Trisomy 21. Risk assessment was based on maternal age, nuchal translucency (NT) thickness and, if available, biochemical markers (β-hCG and PAPP-A). 8812 twin pregnancies including 42 pregnancies with Trisomy 21 had a risk assessment between 2009 and 2017. The detection rate (DR) for pregnancies with a risk assessment based on maternal age and NT only (missing data on biochemical markers, n = 4693) was 69.6% (95% CI: 50.8%-88.4%) for a 6.3% false positive rate (FPR) (95% CI: 5.6%-7.0%), whereas for pregnancies with a risk assessment based on all three parameters (n = 4119) the DR was 89.5% (95% CI: 76.7%-100.0%) for a 7.2% FPR (95% CI: 6.4%-8.0%). The DR of Trisomy 21 in twin pregnancies, seems as high as for singleton pregnancies, when using optimal screening techniques, but the FPR is nearly twice as high.

Prenatally detected isolated ventricular septum defects and the association with chromosomal aberrations-A nationwide register-based study from Denmark.

To evaluate the association between prenatally detected isolated ventricular septum defects (VSDs) and chromosomal aberrations in a nationwide study in Denmark. Nationwide, register-based study with prospectively collected data including all singleton pregnancies from 2014-2018. From the Danish Fetal Medicine Database, we retrieved data on maternal characteristics, first-trimester biomarkers, pre- and postnatal diagnoses, genetic test results, and pregnancy outcomes. VSDs were considered isolated in the absence of other malformations or soft markers, and with a low first-trimester risk assessment for trisomies 21, 18 and 13. All cases of an isolated VSD with a chromosomal anomaly were audited. The genetic tests included karyotyping and chromosomal microarray. We retrieved data on 292 108 singleton pregnancies; 323 registered with a prenatally detected VSD and 697 with a VSD detected postnatally (incidence of 0.35%). Only 1/153 (0.7%, 95% CI 0.02;3.6%) of the isolated prenatally detected VSDs had an abnormal genetic test result (del (8)(q23.1)). Moreover, they had a lower free β-hCG MoM (0.9 MoM vs 0.99 MoM, P = 0.02), and were more likely born small for gestational age (SGA), defined as birthweight 2 or more SD below the mean, compared with the control population (5.2% vs 2.5%, P = 0.03). We found a prevalence of chromosomal aberrations of 0.7% in fetuses with a prenatally detected isolated VSD. Moreover, we found an association between isolated VSDs and a larger proportion being born SGA.

Bacteriuria in Pregnancy in a Danish Contemporary Cohort of Women.

Introduction The purpose of this study is to describe bacteriuria with regard to the uropathogens found in relation to the frequency of urine culture tests in a contemporary cohort of pregnant Danish women. Methods A historical cohort study of 24,817 pregnant women registered in the Danish Fetal Medicine Database at Aarhus University Hospital, from 2010 to 2014. Social security numbers were linked to the microbiological database with the registration of 17,233 urine cultures in 8,807 women. Bacteriuria was defined as 1 × 105 CFU/ml, with a maximum of two urinary pathogens. Streptococcus agalactiae (GBS) was included with 1 × 104 CFU/ml. Data are presented as numbers and proportions in percent. Logistic regression on predictors are presented as crude and adjusted odds ratios (ORc/ORa) with 95% confidence intervals (CIs). Results 42% had a urine sample culture test at the hospital—the majority only once during pregnancy. 96% of all urine culture tests were negative. The bacteriuria incidence was 5.6%. The most frequent uropathogenic bacteria isolated were Escherichia coli (49%), GBS (29%), and Enterococci (10%). We identified subgroups of women with increased likelihood of bacteriuria during pregnancy: age < 25 years, ORa 1.60 (CI 1.26 to 2.02, p < 0.001); age > 34 years, ORa 1.28 (CI 1.01 to 1.61, p = 0.040); Afro-Caribbean origin, ORa 1.872 (CI 1.13 to 3.07, p = 0.014); Asian origin, ORa 2.07 (CI 1.29 to 3.32, p = 0.002); and mixed ethnicity ORa 2.34 (CI 1.23 to 4.46, p = 0.010). Women delivering preterm were more likely to have an episode of bacteriuria during pregnancy OR 2.05 (CI 1.36 to 3.09, p = 0.001). Conclusions 96% of urine culture tests in pregnant women are negative. Optimized urine sampling may change this. Escherichia coli and GBS are predominant uropathogens. Younger and elder women, certain ethnical groups, and women delivering preterm seem more likely to have bacteriuria during pregnancy.

Prevalence of mosaicism in uncultured chorionic villus samples after chromosomal microarray and clinical outcome in pregnancies affected by confined placental mosaicism.

To evaluate the prevalence of mosaicism in chorionic villus sampling (CVS) samples after chromosomal microarray (CMA) and clinical outcome of pregnancies affected by confined placental mosaicism. We retrieved all results from CMA, array-based comparative genomic hybridization, on CVS samples from January 2011 to November 2017 from Central and North Denmark Regions. Mosaic results from uncultured chorionic villi, cytotrophoblasts and mesenchymal cells, after CVS and follow-up on amniocytes, fetal tissue, or postnatal blood were studied and matched with clinical data from The Danish Fetal Medicine Database. Prevalence of mosaicism was 93 out of 2,288 (4.1%) CVS samples of which 17 (18.3%) concerned submicroscopic copy number variations (CNVs) <10 Mb. Follow-up analyses were performed in 62 cases. True fetal mosaicism (TFM) was confirmed in 18.4% (7/38) when mosaicism involved whole chromosome aneuploidy and in 25.0% (6/24), when involving a CNV (P = .59). Median birth weight z-score was higher in cases of confined placental mosaicism for a CNV (0.21) than cases involving whole chromosomes (-0.74) (P = .02). Prevalence of mosaicism in CVS samples is higher after CMA on uncultured tissue than after conventional karyotyping on cultured tissue. The risk of TFM is equally high in cases of mosaicism for CNVs and whole chromosomes.

Do chorionic villus samplings (CVS) or amniocenteses (AC) induce RhD immunisation? An evaluation of a large Danish cohort with no routine administration of anti-D after invasive prenatal testing.

To evaluate the risk of inducing RhD immunisation in pregnancies of RhD-negative mothers with an RhD-positive fetus undergoing chorionic villus samplings (CVS) or amniocenteses (AC). Registry-based study in a Danish cohort which has not been given rhesus prophylaxis. Data were retrieved from the Department of Clinical Immunology at Rigshospitalet. All RhD-negative women carrying an RhD-positive fetus with screen test results from weeks 8-12 and weeks 25-29 were linked to data from the Danish Fetal Medicine Database. Data were divided into cases where no invasive prenatal diagnostic procedure was performed, cases that had AC performed, and cases that had CVS performed. A comparison of the proportion of women who developed RhD immunisation between the two screen tests. The cohort consisted of 10085 women: 9353 had no invasive procedures performed, 189 had AC and 543 had CVS performed. No women were immunised spontaneously or due to the procedure between the first and second screen test in the group with no procedure performed, or in the AC group. One woman was immunised in the CVS group. When comparing the proportion of women who was immunised in the CVS group with the no invasive test group a non-significant difference was found (P=0.055). The RhD immunisation rate before gestational weeks 25-29 in RhD-negative women carrying an RhD-positive fetus is very low, even in women undergoing prenatal invasive testing without rhesus prophylaxis. The RhD immunisation rate during pregnancy is very low even in women undergoing prenatal invasive testing.

Risk of miscarriage in women conceiving after medically assisted reproduction with an ultrasound-verified viable pregnancy at 6-8 weeks' gestation.

What is the risk of miscarriage after a viable fetus verified on ultrasound at 6-8 weeks' gestation among women who conceive with medically assisted reproduction (MAR), stratified by type of fertility treatment? A nationwide register-based cohort study of women identified in the Danish ART-Registry with a viable singleton pregnancy at 6-8 weeks' gestation between 2007 and 2010 (n = 10,011). Women were identified from The Danish Fetal Medicine Database (DFMD), which holds information on early (between 6-8 and 11-14 weeks) and late (between 11-14 and 22 weeks) miscarriages. The late miscarriage rate was compared with a control group of naturally conceived pregnancies with a viable fetus at 11-14 weeks' gestation from 2008 to 2010, identified in the DFMD (n = 146,932). In the MAR1 cohort, the overall miscarriage rate was 11.8% (1091/9261) after an ultrasound verified viable pregnancy at 6-8 weeks' gestation. Most miscarriages occurred before the 11-14-week scan (1035/1091 [94.9%]). The early miscarriage rate was slightly higher in women who conceived with frozen embryo transfer compared with intrauterine insemination (IUI), corresponding to an adjusted OR of 1.31 (1.02 to 1.68). We found no significant risk associated with IVF and intracytoplasmic sperm injection compared with IUI pregnancies. The late miscarriage rate was 0.8% in women conceiving with MAR and 0.6% among controls (P = 0.013). After adjustment for maternal characteristics, none of the fertility treatment types were associated with an increased risk of miscarriage compared with naturally conceiving women.

Outcomes of monoamniotic twin pregnancies managed primarily in outpatient care-a Danish multicenter study.

Monoamniotic twin pregnancies are high-risk pregnancies, and management by inpatient or frequent outpatient care is recommended. We report the outcomes of a national cohort of monoamniotic twin pregnancies managed primarily as outpatients. We prospectively analyzed the recorded data from the Danish Fetal Medicine Database, local databases, and medical records of all monoamniotic twin pregnancies diagnosed at the first trimester scan or later, and managed at the six major fetal medicine centers in Denmark over a 10-year period. Sixty-one monoamniotic twin pregnancies were included. Thirteen pregnancies were terminated early. Of the remaining 48 pregnancies with a normal first trimester scan, there were 36 fetal losses (25 spontaneous miscarriages <22+0 weeks, 3 late terminations and 8 intrauterine deaths >22weeks) and 60 liveborn children (62.5%), all of whom were delivered by cesarean delivery at a median gestational age of 33+0 weeks. Three children had minor malformations and there was 1 pregnancy with twin-to-twin transfusion syndrome. After 26+0 weeks, 78.8% were managed as outpatients. Intrauterine death occurred in 3.8% of outpatients and in 28.6% of inpatients (admitted due to complications). At weeks 32, 33 and 34, the prospective risk of intrauterine death was 6.9%, 4.2% and 5.9%, respectively. In this nationwide, unselected population, only 62.5% of fetuses with a normal first trimester scan were born alive. In contrast, the mortality was 3.8% after 26weeks among the 78.8% of the cohort that was managed as outpatients. More knowledge is still needed to predict which pregnancies are at the highest risk of intrauterine death.

The Danish Medical Birth Register.

The Danish Medical Birth Register was established in 1973. It is a key component of the Danish health information system. The register enables monitoring of the health of pregnant women and their offspring, it provides data for quality assessment of the perinatal care in Denmark, and it is used extensively for research. The register underwent major changes in construction and content in 1997, and new variables have been added during the last 20years. The aim was to provide an updated description of the register focusing on structure, content, and coverage since 1997. The register includes data on all births in Denmark and comprises primarily of data from the Danish National Patient Registry supplemented with forms on home deliveries and stillbirths. It contains information on maternal age provided by the Civil Registration System. Information on pre-pregnancy body mass index and smoking in first trimester is collected in early pregnancy (first antenatal visit). The individual-level data can be linked to other Danish health registers such as the National Patient Registry and the Danish National Prescription Registry. The register informs several other registers/databases such as the Danish Twin Registry and the Danish Fetal Medicine Database. Aggregated data can be publicly accessed on the Danish Health Data Authority web page ( www.esundhed.dk/sundhedsregistre/MFR ). Researchers can obtain access to individual-level pseudo-anonymised data via servers at Statistics Denmark and the Danish Health Data Authority.