Preeclampsia and COVID-19: results from the INTERCOVID prospective longitudinal study

Coronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Hipertensió gestacional; PreeclampsiaCoronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Hipertension gestacional; PreeclampsiaCoronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Gestational hypertension; PreeclampsiaBackground It is unclear whether the suggested link between COVID-19 during pregnancy and preeclampsia is an independent association or if these are caused by common risk factors. Objective This study aimed to quantify any independent association between COVID-19 during pregnancy and preeclampsia and to determine the effect of these variables on maternal and neonatal morbidity and mortality. Study Design This was a large, longitudinal, prospective, unmatched diagnosed and not-diagnosed observational study assessing the effect of COVID-19 during pregnancy on mothers and neonates. Two consecutive not-diagnosed women were concomitantly enrolled immediately after each diagnosed woman was identified, at any stage during pregnancy or delivery, and at the same level of care to minimize bias. Women and neonates were followed until hospital discharge using the standardized INTERGROWTH-21 st protocols and electronic data management system. A total of 43 institutions in 18 countries contributed to the study sample. The independent association between the 2 entities was quantified with the risk factors known to be associated with preeclampsia analyzed in each group. The outcomes were compared among women with COVID-19 alone, preeclampsia alone, both conditions, and those without either of the 2 conditions. Results We enrolled 2184 pregnant women; of these, 725 (33.2%) were enrolled in the COVID-19 diagnosed and 1459 (66.8%) in the COVID-19 not-diagnosed groups. Of these women, 123 had preeclampsia of which 59 of 725 (8.1%) were in the COVID-19 diagnosed group and 64 of 1459 (4.4%) were in the not-diagnosed group (risk ratio, 1.86; 95% confidence interval, 1.32–2.61). After adjustment for sociodemographic factors and conditions associated with both COVID-19 and preeclampsia, the risk ratio for preeclampsia remained significant among all women (risk ratio, 1.77; 95% confidence interval, 1.25–2.52) and nulliparous women specifically (risk ratio, 1.89; 95% confidence interval, 1.17–3.05). There was a trend but no statistical significance among parous women (risk ratio, 1.64; 95% confidence interval, 0.99–2.73). The risk ratio for preterm birth for all women diagnosed with COVID-19 and preeclampsia was 4.05 (95% confidence interval, 2.99–5.49) and 6.26 (95% confidence interval, 4.35–9.00) for nulliparous women. Compared with women with neither condition diagnosed, the composite adverse perinatal outcome showed a stepwise increase in the risk ratio for COVID-19 without preeclampsia, preeclampsia without COVID-19, and COVID-19 with preeclampsia (risk ratio, 2.16; 95% confidence interval, 1.63–2.86; risk ratio, 2.53; 95% confidence interval, 1.44–4.45; and risk ratio, 2.84; 95% confidence interval, 1.67–4.82, respectively). Similar findings were found for the composite adverse maternal outcome with risk ratios of 1.76 (95% confidence interval, 1.32–2.35), 2.07 (95% confidence interval, 1.20–3.57), and 2.77 (95% confidence interval, 1.66–4.63). The association between COVID-19 and gestational hypertension and the direction of the effects on preterm birth and adverse perinatal and maternal outcomes, were similar to preeclampsia, but confined to nulliparous women with lower risk ratios. Conclusion COVID-19 during pregnancy is strongly associated with preeclampsia, especially among nulliparous women. This association is independent of any risk factors and preexisting conditions. COVID-19 severity does not seem to be a factor in this association. Both conditions are associated independently of and in an additive fashion with preterm birth, severe perinatal morbidity and mortality, and adverse maternal outcomes. Women with preeclampsia should be considered a particularly vulnerable group with regard to the risks posed by COVID-19.The study was supported by the COVID-19 Research Response Fund from the University of Oxford (Ref 0009083). A.T.P. is supported by the Oxford Partnership Comprehensive Biomedical Research Centre with funding from the National Institute for Health Research (NIHR) Biomedical Research Centre funding scheme. The funding organization had no involvement in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript, and decision to submit the manuscript for publication

Pregnancy outcomes and vaccine effectiveness during the period of omicron as the variant of concern, INTERCOVID-2022: a multinational, observational study

Pregnancy outcomes; Vaccine effectiveness; OmicronResultados del embarazo; Efectividad de la vacuna; OmicronResultats de l'embaràs; Eficàcia de la vacuna; OmicronBackground In 2021, we showed an increased risk associated with COVID-19 in pregnancy. Since then, the SARS-CoV-2 virus has undergone genetic mutations. We aimed to examine the effects on maternal and perinatal outcomes of COVID-19 during pregnancy, and evaluate vaccine effectiveness, when omicron (B.1.1.529) was the variant of concern. Methods INTERCOVID-2022 is a large, prospective, observational study, involving 41 hospitals across 18 countries. Each woman with real-time PCR or rapid test, laboratory-confirmed COVID-19 in pregnancy was compared with two unmatched women without a COVID-19 diagnosis who were recruited concomitantly and consecutively in pregnancy or at delivery. Mother and neonate dyads were followed until hospital discharge. Primary outcomes were maternal morbidity and mortality index (MMMI), severe neonatal morbidity index (SNMI), and severe perinatal morbidity and mortality index (SPMMI). Vaccine effectiveness was estimated, adjusted by maternal risk profile. Findings We enrolled 4618 pregnant women from Nov 27, 2021 (the day after WHO declared omicron a variant of concern), to June 30, 2022: 1545 (33%) women had a COVID-19 diagnosis (median gestation 36·7 weeks [IQR 29·0–38·9]) and 3073 (67%) women, with similar demographic characteristics, did not have a COVID-19 diagnosis. Overall, women with a diagnosis had an increased risk for MMMI (relative risk [RR] 1·16 [95% CI 1·03–1·31]) and SPMMI (RR 1·21 [95% CI 1·00–1·46]). Women with a diagnosis, compared with those without a diagnosis, also had increased risks of SNMI (RR 1·23 [95% CI 0·88–1·71]), although the lower bounds of the 95% CI crossed unity. Unvaccinated women with a COVID-19 diagnosis had a greater risk of MMMI (RR 1·36 [95% CI 1·12–1·65]). Severe COVID-19 symptoms in the total sample increased the risk of severe maternal complications (RR 2·51 [95% CI 1·84–3·43]), perinatal complications (RR 1·84 [95% CI 1·02–3·34]), and referral, intensive care unit (ICU) admission, or death (RR 11·83 [95% CI 6·67–20·97]). Severe COVID-19 symptoms in unvaccinated women increased the risk of MMMI (RR 2·88 [95% CI 2·02–4·12]) and referral, ICU admission, or death (RR 20·82 [95% CI 10·44–41·54]). 2886 (63%) of 4618 total participants had at least a single dose of any vaccine, and 2476 (54%) of 4618 had either complete or booster doses. Vaccine effectiveness (all vaccines combined) for severe complications of COVID-19 for all women with a complete regimen was 48% (95% CI 22–65) and 76% (47–89) after a booster dose. For women with a COVID-19 diagnosis, vaccine effectiveness of all vaccines combined for women with a complete regimen was 74% (95% CI 48–87) and 91% (65–98) after a booster dose. Interpretation COVID-19 in pregnancy, during the first 6 months of omicron as the variant of concern, was associated with increased risk of severe maternal morbidity and mortality, especially among symptomatic and unvaccinated women. Women with complete or boosted vaccine doses had reduced risk for severe symptoms, complications, and death. Vaccination coverage among pregnant women remains a priority

Management and outcome of pregnancies in women with red cell isoimmunization: a 15-year observational study from a tertiary care university hospital

Isoimmunization; Newborn hemolytic disease; Intrauterine transfusionIsoinmunización; Enfermedad hemolítica del recién nacido; Transfusión intrauterinaIsoimmunització; Malaltia hemolítica del nounat; Transfusió intrauterinaBackground: The aims of this study were to determine the prevalence of the different anti-erythrocytic alloantibodies, to describe pregnancy outcomes according to a low-risk and high-risk classification for fetal anemia and to determine the factors that influence adverse perinatal outcomes. Methods: This retrospective observational study included women referred to our center following the identification of maternal anti-erythrocytic alloantibodies between 2002 and 2017. Pregnancies were classified as high risk for fetal anemia in cases with clinically significant antibodies, no fetal-maternal compatibility and titers ≥1:16 or any titration in cases of Kell system incompatibility. In high-risk pregnancies, maternal antibody titration and the fetal middle cerebral artery peak systolic velocity (MCA-PSV) were monitored. Low-risk pregnancies underwent routine pregnancy follow-up. Results: Maternal antibodies were found in 337 pregnancies, and 259 (76.9%) of these antibodies were clinically significant. The most frequent antibodies were anti-D (53%) and anti-K (19%). One hundred forty-three pregnancies were classified as low risk for fetal anemia, 65 (25%) cases were classified as no fetal-maternal incompatibility, 78 had clinically nonsignificant antibodies, 4 (2.8%) resulted in first-trimester pregnancy loss, and 139 (97.2%) resulted in livebirths. Of the 194 high-risk pregnancies, 38 had titers 1.5 MoM, resulting in 3 intrauterine deaths, 6 terminations and 48 livebirths. Ninety-two intrauterine transfusions were performed in 45 fetuses (87% anti-D). Adverse outcomes were related to a MCA-PSV > 1.5 MoM (p < 0.001), hydrops (p < 0.001) and early gestational age at first transfusion (p = 0.029) Conclusion: Anti-D remains the most common antibody in fetuses requiring intrauterine transfusion. A low or high-risk classification for fetal anemia based on the type of antibody, paternal phenotype and fetal antigen allows follow-up of the pregnancy accordingly, with good perinatal outcomes in the low-risk group. In the high-risk group, adverse perinatal outcomes are related to high MCA-PSV, hydrops and early gestational age at first transfusion

Clinical application of a contingent screening strategy for trisomies with cell-free DNA: a pilot study

Cell-free DNA; Contingent screening; Fetal trisomyADN libre de células; Cribado contingente; Trisomia fetalADN lliure de cèl·lules; Cribratge contingent; Trisomia fetalBACKGROUND: Different strategies have been designed for clinical implementation of cell-free DNA (cfDNA) testing. We aimed to evaluate the performance of a contingent strategy based on conventional screening and offering cfDNA to the intermediate-risk group, for the screening for trisomies 21, 18 and 13. Secondary objectives were to assess the uptake of cfDNA in women with intermediate-risk, to evaluate the performance of cfDNA testing, and the preferences of pregnant women with intermediate risk. METHODS: Prospective observational pilot study between February 2016 and March 2017. Singleton pregnancies with a known outcome were included in the study. At the conventional screening (first trimester combined test or second trimester quadruple test) women were classified in high (risk ≥1:250) or low risk (< 1:250). For the study, a contingent strategy was applied: following the conventional screening women were classified into three groups: high risk (risk ≥1:10 or nuchal translucency ≥3 mm), intermediate-risk (risk 1:11 to 1:1500) and low risk (< 1:1500), and a cfDNA test was offered to those at the intermediate risk. RESULTS: For the analysis, 2639 women were included, 2422 (91.8%) had a first trimester combined test and 217 (8.2%) a second trimester quadruple test. There were 5 cases of trisomy 21, 4 of trisomy 18 and none of trisomy 13. For the contingent strategy, the detection rate and false positive rates were 88.9% (8/9) and 1.3% (35/2630), respectively. For the conventional strategy, the detection rate and false positive rates were 66.7% (6/9) and 5.3% (140/2630), respectively. The cfDNA test had a detection rate for trisomy 21 of 100% (3 out of 3), and a false positive rate of 0.2% (1/466). In a survey, 81.8% (374/457) of women in the intermediate-risk group would choose cfDNA testing as the second line test, mainly due to the lack of risk for the fetus. CONCLUSION: A contingent screening strategy for trisomies 21, 18 and 13, based on conventional screening, and offering a cfDNA test to women with a risk between 1:11 to 1:1500, reduced the false positive rate and increased the detection rate for these trisomies. Moreover, this strategy is well accepted by women.The study was financially supported by Ariosa Diagnostics, Inc. San Jose, CA, US

Gestational age-based reference ranges for cervical length and preterm birth prediction in triplet pregnancies: an observational retrospective study

Cervical length; Preterm delivery; Triplet pregnancyLongitud cervical; Parto prematuro; Embarazo de trillizosLongitud cervical; Part prematur; Embaràs de trillissosObjectives To develop gestational age-based reference ranges for cervical length in triplet pregnancies. The secondary objective was to assess the performance of cervical length measured between 18 and 20 + 6 days for the prediction of preterm delivery before 28 and 32 weeks, respectively. Methods Observational retrospective study of triplet pregnancies in three Spanish tertiary-care hospitals between 2001 and 2019. Cervical length measurements were consecutively obtained between 15 and 34 weeks of gestation. Pregnancies undergoing multifetal reduction or fetal surgery were excluded. Results Two hundred and six triplet pregnancies were included in the final analysis. There was a quadratic decrease in cervical length with gestational age. The median and fifth centiles for cervical length at 20 weeks were 35 and 13 mm. In the prediction of preterm birth < 28 weeks, for a false positive rate of 5%, and 10%, the detection rates were 40.9%, and 40.9%, respectively, and the prediction of preterm birth < 32 weeks, 22.0% and 26.0%, respectively. Conclusions In triplet pregnancies, cervical length decreases with gestational age. The performance of cervical length at 18–20 + 6 in screening for preterm birth before 28 and 32 weeks is poor

Confirmation of preeclampsia-like syndrome induced by severe COVID-19: an observational study

COVID-19; Preeclampsia; PregnancyCOVID-19; Preeclampsia; EmbarazoCOVID-19; Preeclampsia; EmbaràsBACKGROUND Since the outbreak of the COVID-19 pandemic, some studies have reported an increased preeclampsia incidence in pregnant women with SARS-CoV-2 infection. Several explanations for this association have been proposed, including a preeclampsia-like syndrome induced by severe COVID-19. This syndrome was described in a small case series and has not been confirmed in larger studies, and its effect on perinatal outcomes has not been studied. OBJECTIVE This study aimed to confirm the preeclampsia-like syndrome because of COVID-19 and to investigate its implications on pregnancy outcomes and prognosis. STUDY DESIGN This was a prospective, observational study conducted in a tertiary referral hospital. The inclusion criteria were pregnant women admitted to the intensive care unit for severe pneumonia because of COVID-19. They were classified into 3 groups based on clinical and laboratory findings: preeclampsia, preeclampsia-like syndrome, and women without preeclampsia features. The 3 cohorts were analyzed and compared at 3 different times: before, during, and after severe pneumonia. The main outcomes were incidence of adverse perinatal outcomes and signs and symptoms of PE, such as hypertension, proteinuria, thrombocytopenia, elevated liver enzymes, and increased angiogenic factors (soluble fms-like tyrosine kinase 1–to–placental growth factor ratio). RESULTS A total of 106 women were admitted to the intensive care unit because of severe pneumonia, and 68 women were included in the study. Of those, 53 (50.0%) did not meet the diagnostic criteria for preeclampsia and remained pregnant after pneumonia (non-preeclampsia); 7 (6.6%) met the diagnostic criteria for preeclampsia, had abnormal (>38) soluble fms-like tyrosine kinase 1–to–placental growth factor ratio (preeclampsia), and delivered during severe pneumonia, and 8 (7.5%) met the diagnostic criteria for preeclampsia, had normal (≤38) soluble fms-like tyrosine kinase 1–to–placental growth factor ratio (preeclampsia like), and did not deliver during pneumonia. Despite not having delivered, most preeclampsia-related features improved after severe pneumonia in women with preeclampsia-like syndrome. Women with preeclampsia had significantly poorer outcomes than women with preeclampsia-like syndrome or without preeclampsia. CONCLUSION More than 50% of women with severe COVID-19 and diagnostic criteria for preeclampsia may not be preeclampsia but a preeclampsia-like syndrome, which may affect up to 7.5% of women with severe COVID-19. Preeclampsia-like syndrome might have similar perinatal outcomes to those of normotensive women with severe pneumonia because of COVID-19. For these reasons, preeclampsia-like syndrome should be excluded by using soluble fms-like tyrosine kinase 1–to–placental growth factor ratio in future research and before making clinical decisions

Reference values for interleukin-6 in the amniotic fluid of asymptomatic pregnant women

Amniocentesis; Interleukin-6; Intra-amniotic inflammationAmniocentesi; Interleucina-6; Inflamació intraamniòticaAmniocentesis; Interleucina-6; Inflamación intraamnióticaIntroduction Nowadays, proinflammatory factors are considered to play an important role in the pathophysiology of threatened preterm labor or chorioamnionitis. The aim of this study was to establish the normal reference range for interleukin-6 (IL-6) levels in the amniotic fluid and to identify factors which may alter this value. Material and methods Prospective study in a tertiary-level center including asymptomatic pregnant women undergoing amniocentesis for genetic studies from October 2016 to September 2019. IL-6 measurements in amniotic fluid were performed using a fluorescence immunoassay with microfluidic technology (ELLA Proteinsimple, Bio Techne). Maternal history and pregnancy data were also recorded. Results This study included 140 pregnant women. Of those, women who underwent termination of pregnancy were excluded. Therefore, a total of 98 pregnancies were included in the final statistical analysis. The mean gestational age was 21.86 weeks (range: 15–38.7) at the time of amniocentesis, and 38.6 weeks (range: 30.9–41.4) at delivery. No cases of chorioamnionitis were reported. The log10 IL-6 values follow a normal distribution (W = 0.990, p = 0.692). The median, and the 5th, 10th, 90th, and 95th percentiles for IL-6 levels were 573, 105, 130, 1645, and 2260 pg/mL, respectively. The log10 IL-6 values were not affected by gestational age (p = 0.395), maternal age (p = 0.376), body mass index (p = 0.551), ethnicity (p = 0.467), smoking status (p = 0.933), parity (p = 0.557), method of conception (p = 0.322), or diabetes mellitus (p = 0.381). Conclusions The log10 IL-6 values follow a normal distribution. IL-6 values are independent of gestational age, maternal age, body mass index, ethnicity, smoking status, parity and method of conception. Our study provides a normal reference range for IL-6 levels in the amniotic fluid that can be used in future studies. We also observed that normal IL-6 values were higher in the amniotic fluid than in serum.Some of the authors are members of the European Reference Network on Rare Congenital Malformations and Rare Intellectual Disability ERN-ITHACA (EU Framework Partnership Agreement ID: 3HP-HP-FPA ERN-01-2016/739516)

Social Support and Mental Health in the Postpartum Period in Times of SARS-CoV-2 Pandemic: Spanish Multicentre Cohort Study

COVID-19; Anxiety; PregnancyCOVID-19; Ansiedad; EmbarazoCOVID-19; Ansietat; EmbaràsBackground: To explore the depression and anxiety symptoms in the postpartum period during the SARS-CoV-2 pandemic and to identify potential risk factors. Methods: A multicentre observational cohort study including 536 women was performed at three hospitals in Spain. The Edinburgh Postnatal Depression Scale (EPDS), the State-Trait Anxiety Inventory (STAI) Scale, the Medical Outcomes Study Social Support Survey (MOS-SSS), and the Postpartum Bonding Questionnaire (PBQ) were assessed after birth. Depression (EPDS) and anxiety (STAI) symptoms were measured, and the cut-off scores were set at 10 and 13 for EPDS, and at 40 for STAI. Results: Regarding EPDS, 32.3% (95% CI, 28% to 36.5%) of women had a score ≥ 10, and 17.3% (95% CI, 13.9% to 20.7%) had a score ≥ 13. Women with an STAI score ≥ 40 accounted for 46.8% (95% CI, 42.3% to 51.2%). A lower level of social support (MOS-SSS), a fetal malformation diagnosis and a history of depression (p = 0.000, p = 0.019 and p = 0.043) were independent risk factors for postpartum depression. A lower level of social support and a history of mental health disorders (p = 0.000, p = 0.003) were independent risk factors for postpartum anxiety. Conclusion: During the SARS-CoV-2 pandemic, an increase in symptoms of anxiety and depression were observed during the postpartum period

Valoración del ductus venoso en el primer trimestre en el cribado de anomalías cromosómicas fetales y defectos cardiacos

[eng] THESIS SUMMARY: BACKGROUND: Abnormal ductus venosus flow at 11-13 weeks has been associated to fetal chromosomal abnormalities and cardiac defects. The hypothesis of the studies is that flow through the ductus venosus can be assessed routinely at 11-13 weeks of gestation and that abnormal flow at this scan can help identify fetal chromosomal and structural defects as well as adverse pregnancy outcome. STUDIES: In the first study, ten sonographers received practical training in accurate assessment of the ductus venosus and performed 300 examinations each. The sonographers required an average of 80 examinations before they could successfully examine the ductus venosus flow. In the second study ductus venosus flow was assessed immediately before chorion villous sampling (CVS) in fetuses with nuchal translucency (NT) thickness of 3.5 mm or more. A fetal echocardiography was performed in euploid fetuses at 11-13 weeks and/or 18-22 weeks. Reverse or absent flow during atrial contraction was observed in 68.8% of the fetuses with cardiac defects and in 22.9% with no cardiac defects. In the third study screening by the combined test was performed in singleton pregnancies, including 19,614 with euploid fetuses, 122 with trisomy 21, 36 with trisomy 18, 20 with trisomy 13 and 8 with Turner syndrome. We examined the performance of two screening strategies: firstly, assessment of the a-wave in all patients and secondly, first-stage screening using the combined test in all patients followed by second-stage assessment of the a-wave only in those with an intermediate risk of 1 in 51 to 1 in 1,000 after the first-stage. Reversed a-wave was observed in 3.2% of the euploid fetuses and in 66.4%, 58.3%, 55.0% and 75.0% of fetuses with trisomies 21, 18 and 13 and Turner syndrome, respectively. Inclusion of ductus venosus flow in all pregnancies would detect 96%, 92%, 100% and 100% of trisomies 21, 18 and 13 and Turner syndrome, respectively, at a false positive rate of 3%. The same detection rates were achieved with the two-stage strategy at a false positive rate of 2.6%. In the fourth study the patients were subdivided into five groups: normal outcome (n=10,120), miscarriage or fetal death (n=185), abnormal karyotype (n=95), major cardiac (n=20) or non-cardiac defect (n=70). The prevalence of reversed a-wave was significantly higher in the groups with miscarriage or fetal death (10.8%), abnormal karyotype (62.1%) and fetal cardiac defect (25.0%) but not non-cardiac defect (4.3%) than in the normal outcome group (3.7%). The fifth study was a prospective study in 516 dichorionic and 179 monochorionic twin pregnancies. The prevalence of reversed a-wave in the fetal ductus venosus was compared between monochorionic and dichorionic pregnancies and between those with and without pregnancy complications. The prevalence of reversed a-wave in at least one of the fetuses was significantly higher in monochorionic than in dichorionic pregnancies (18.4% vs. 8.3%, p<0.001) and in pregnancies complicated by miscarriage (28.6%, p=0.005), fetal aneuploidy (70.0%, p<0.001) and twin-to-twin-transfusion syndrome (TTTS) (38.5%, p<0.001) compared to the pregnancies with two healthy live births (7.7%). Pregnancy outcome was normal in 76.7% dichorionic and in 42.4% monochorionic twins with reversed a-wave in at least one of the fetuses. CONCLUSIONS: After an extensive supervised training, ductus venosus flow assessment can be incorporated into the first trimester scan, where it improves the performance of screening for chromosomal defects and cardiac defects, and it helps to identify the fetuses with a higher risk of death. Similarly, in twin pregnancies ductus venosus assessment identifies the pregnancies with a higher risk of having a fetus with an aneuploidy, those with a higher risk of miscarriage, and those that will subsequently develop TTTS. KEY WORDS: Ductus venosus, First trimester, Chromosomal abnormality, Cardiac effect, Adverse outcome, Twin pregnanc

First trimester assessment of ductus venosus in screening for fetal chromosomal and cardiac defects / Valoración del ductus venoso en el primer trimestre en el cribado de anomalías cromosómicas fetales y defectos cardiacos

THESIS SUMMARY:BACKGROUND: Abnormal ductus venosus flow at 11-13 weeks has been associated to fetal chromosomal abnormalities and cardiac defects.The hypothesis of the studies is that flow through the ductus venosus can be assessed routinely at 11-13 weeks of gestation and that abnormal flow at this scan can help identify fetal chromosomal and structural defects as well as adverse pregnancy outcome.STUDIES:In the first study, ten sonographers received practical training in accurate assessment of the ductus venosus and performed 300 examinations each. The sonographers required an average of 80 examinations before they could successfully examine the ductus venosus flow. In the second study ductus venosus flow was assessed immediately before chorion villous sampling (CVS) in fetuses with nuchal translucency (NT) thickness of 3.5 mm or more. A fetal echocardiography was performed in euploid fetuses at 11-13 weeks and/or 18-22 weeks. Reverse or absent flow during atrial contraction was observed in 68.8% of the fetuses with cardiac defects and in 22.9% with no cardiac defects. In the third study screening by the combined test was performed in singleton pregnancies, including 19,614 with euploid fetuses, 122 with trisomy 21, 36 with trisomy 18, 20 with trisomy 13 and 8 with Turner syndrome. We examined the performance of two screening strategies: firstly, assessment of the a-wave in all patients and secondly, first-stage screening using the combined test in all patients followed by second-stage assessment of the a-wave only in those with an intermediate risk of 1 in 51 to 1 in 1,000 after the first-stage. Reversed a-wave was observed in 3.2% of the euploid fetuses and in 66.4%, 58.3%, 55.0% and 75.0% of fetuses with trisomies 21, 18 and 13 and Turner syndrome, respectively. Inclusion of ductus venosus flow in all pregnancies would detect 96%, 92%, 100% and 100% of trisomies 21, 18 and 13 and Turner syndrome, respectively, at a false positive rate of 3%. The same detection rates were achieved with the two-stage strategy at a false positive rate of 2.6%.In the fourth study the patients were subdivided into five groups: normal outcome (n=10,120), miscarriage or fetal death (n=185), abnormal karyotype (n=95), major cardiac (n=20) or non-cardiac defect (n=70). The prevalence of reversed a-wave was significantly higher in the groups with miscarriage or fetal death (10.8%), abnormal karyotype (62.1%) and fetal cardiac defect (25.0%) but not non-cardiac defect (4.3%) than in the normal outcome group (3.7%). The fifth study was a prospective study in 516 dichorionic and 179 monochorionic twin pregnancies. The prevalence of reversed a-wave in the fetal ductus venosus was compared between monochorionic and dichorionic pregnancies and between those with and without pregnancy complications. The prevalence of reversed a-wave in at least one of the fetuses was significantly higher in monochorionic than in dichorionic pregnancies (18.4% vs. 8.3%, pCONCLUSIONS: After an extensive supervised training, ductus venosus flow assessment can be incorporated into the first trimester scan, where it improves the performance of screening for chromosomal defects and cardiac defects, and it helps to identify the fetuses with a higher risk of death. Similarly, in twin pregnancies ductus venosus assessment identifies the pregnancies with a higher risk of having a fetus with an aneuploidy, those with a higher risk of miscarriage, and those that will subsequently develop TTTS.KEY WORDS: Ductus venosus, First trimester, Chromosomal abnormality, Cardiac effect, Adverse outcome, Twin pregnanc