The Effect of Vanishing Twin on First- and Second-Trimester Maternal Serum Markers and Nuchal Translucency: A Multicenter Prospective Cohort Study.

BACKGROUND: The purpose of this study was to evaluate the effect of vanishing twin (VT) on maternal serum marker concentrations and nuchal translucency (NT). METHODS: This is a secondary analysis of a multicenter prospective cohort study in 12 institutions. Serum concentrations of pregnancy-associated plasma protein-A in the first trimester and alpha-fetoprotein (AFP), total human chorionic gonadotrophin, unconjugated estriol, and inhibin A in the second trimester were measured, and NT was measured between 10 and 14 weeks of gestation. RESULTS: Among 6,793 pregnant women, 5,381 women were measured for serum markers in the first or second trimester, including 65 cases in the VT group and 5,316 cases in the normal singleton group. The cases in the VT group had a higher median multiple of the median value of AFP and inhibin A than the normal singleton group. The values of other serum markers and NT were not different between the two groups. After the permutation test with adjustment, AFP and inhibin A remained significant differences. The frequency of abnormally increased AFP was also higher in the VT group than in the normal singleton group. CONCLUSION: VT can be considered as an adjustment factor for risk assessment in the second-trimester serum screening test.

Clinical Practice Guidelines for Prenatal Aneuploidy Screening and Diagnostic Testing from Korean Society of Maternal-Fetal Medicine: (2) Invasive Diagnostic Testing for Fetal Chromosomal Abnormalities.

The Korean Society of Maternal Fetal Medicine proposed the first Korean guideline on prenatal aneuploidy screening and diagnostic testing, in April 2019. The clinical practice guideline (CPG) was developed for Korean women using an adaptation process based on good-quality practice guidelines, previously developed in other countries, on prenatal screening and invasive diagnostic testing for fetal chromosome abnormalities. We reviewed current guidelines and developed a Korean CPG on invasive diagnostic testing for fetal chromosome abnormalities according to the adaptation process. Recommendations for selected 11 key questions are: 1) Considering the increased risk of fetal loss in invasive prenatal diagnostic testing for fetal genetic disorders, it is not recommended for all pregnant women aged over 35 years. 2) Because early amniocentesis performed before 14 weeks of pregnancy increases the risk of fetal loss and malformation, chorionic villus sampling (CVS) is recommended for pregnant women who will undergo invasive prenatal diagnostic testing for fetal genetic disorders in the first trimester of pregnancy. However, CVS before 9 weeks of pregnancy also increases the risk of fetal loss and deformity. Thus, CVS is recommended after 9 weeks of pregnancy. 3) Amniocentesis is recommended to distinguish true fetal mosaicism from confined placental mosaicism. 4) Anti-immunoglobulin should be administered within 72 hours after the invasive diagnostic testing. 5) Since there is a high risk of vertical transmission, an invasive prenatal diagnostic testing is recommended according to the clinician's discretion with consideration of the condition of the pregnant woman. 6) The use of antibiotics is not recommended before or after an invasive diagnostic testing. 7) The chromosomal microarray test as an alternative to the conventional cytogenetic test is not recommended for all pregnant women who will undergo an invasive diagnostic testing. 8) Amniocentesis before 14 weeks of gestation is not recommended because it increases the risk of fetal loss and malformation. 9) CVS before 9 weeks of gestation is not recommended because it increases the risk of fetal loss and malformation. 10) Although the risk of fetal loss associated with invasive prenatal diagnostic testing (amniocentesis and CVS) may vary based on the proficiency of the operator, the risk of fetal loss due to invasive prenatal diagnostic testing is higher in twin pregnancies than in singleton pregnancies. 11) When a monochorionic twin is identified in early pregnancy and the growth and structure of both fetuses are consistent, an invasive prenatal diagnostic testing can be performed on one fetus alone. However, an invasive prenatal diagnostic testing is recommended for each fetus in cases of pregnancy conceived via in vitro fertilization, or in cases in which the growth of both fetuses differs, or in those in which at least one fetus has a structural abnormality. The guidelines were established and approved by the Korean Academy of Medical Sciences. This guideline is revised and presented every 5 years.

Clinical Practice Guidelines for Prenatal Aneuploidy Screening and Diagnostic Testing from Korean Society of Maternal-Fetal Medicine: (1) Prenatal Aneuploidy Screening.

In 2019, the Korean Society of Maternal-Fetal Medicine developed the first Korean clinical practice guidelines for prenatal aneuploidy screening and diagnostic testing. These guidelines were developed by adapting established clinical practice guidelines in other countries that were searched systematically, and the guidelines aim to assist in decision making of healthcare providers providing prenatal care and to be used as a source for education and communication with pregnant women in Korea. This article delineates clinical practice guidelines specifically for maternal serum screening for fetal aneuploidy and cell-free DNA (cfDNA) screening. A total of 19 key questions (12 for maternal serum and 7 for cfDNA screening) were defined. The main recommendations are: 1) Pregnant women should be informed of common fetal aneuploidy that can be detected, risks for chromosomal abnormality according to the maternal age, detection rate and false positive rate for common fetal aneuploidy with each screening test, limitations, as well as the benefits and risks of invasive diagnostic testing, 2) It is ideal to give counseling about prenatal aneuploidy screening and diagnostic testing at the first prenatal visit, and counseling is recommended to be given early in pregnancy, 3) All pregnant women should be informed about maternal serum screening regardless of their age, 4) cfDNA screening can be used for the screening of trisomy 21, 18, 13 and sex-chromosome aneuploidy. It is not recommended for the screening of microdeletion, 5) The optimal timing of cfDNA screening is 10 weeks of gestation and beyond, and 6) cfDNA screening is not recommended for women with multiple gestations. The guideline was reviewed and approved by the Korean Academy of Medical Sciences.

Clinical Validation of Non-Invasive Prenatal Testing for Fetal Common Aneuploidies in 1,055 Korean Pregnant Women: a Single Center Experience.

BACKGROUND: Non-invasive prenatal testing (NIPT) using cell-free fetal DNA from maternal plasma for fetal aneuploidy identification is expanding worldwide. The objective of this study was to evaluate the clinical utility of NIPT for the detection of trisomies 21, 18, and 13 of high-risk fetus in a large Korean population. METHODS: This study was performed retrospectively, using stored maternal plasma from 1,055 pregnant women with singleton pregnancies who underwent invasive prenatal diagnosis because of a high-risk indication for chromosomal abnormalities. The NIPT results were confirmed by karyotype analysis. RESULTS: Among 1,055 cases, 108 cases of fetal aneuploidy, including trisomy 21 (n = 57), trisomy 18 (n = 42), and trisomy 13 (n = 9), were identified by NIPT. In this study, NIPT showed 100% sensitivity and 99.9% specificity for trisomy 21, and 92.9% sensitivity and 100% specificity for trisomy 18, and 100% sensitivity and 99.9% specificity for trisomy 13. The overall positive predictive value (PPV) was 98.1%. PPVs for trisomies 21, 18, and 13 ranged from 90.0% to 100%. CONCLUSION: This study demonstrates that our NIPT technology is reliable and accurate when applied to maternal DNA samples collected from pregnant women. Further large prospective studies are needed to adequately assess the performance of NIPT.

Sex-dependent effects of antenatal glucocorticoids on insulin sensitivity in adult sheep: role of the adipose tissue renin angiotensin system.

Exposure to glucocorticoids in utero is associated with changes in organ function and structure in the adult. The aims of this study were to characterize the effects of antenatal exposure to glucocorticoids on glucose handling and the role of adipose tissue. Pregnant sheep received betamethasone (Beta, 0.17 mg/kg) or vehicle 24 h apart at 80 days of gestation and allowed to deliver at term. At 9 mo, male and female offspring were fed at either 100% of nutritional allowance (lean) or ad libitum for 3 mo (obese). At 1 yr, they were chronically instrumented under general anesthesia. Glucose tolerance was evaluated using a bolus of glucose (0.25 g/kg). Adipose tissue was harvested after death to determine mRNA expression levels of angiotensinogen (AGT), angiotensin-converting enzyme (ACE) 1, ACE2, and peroxisome proliferator-activated receptor γ (PPAR-γ). Data are expressed as means ± SE and analyzed by ANOVA. Sex, obesity, and Beta exposure had significant effects on glucose tolerance and mRNA expression. Beta impaired glucose tolerance in lean females but not males. Superimposed obesity worsened the impairment in females and unmasked the defect in males. Beta increased ACE1 mRNA in females and males and AGT in females only (P < 0.05 by three-way ANOVA). Obesity increased AGT in females but had no effect on ACE1 in either males or females. PPAR-γ mRNA exhibited a significant sex (F = 42.8; P < 0.01) and obesity (F = 6.9; P < 0.05) effect and was significantly higher in males (P < 0.01 by three-way ANOVA). We conclude that adipose tissue may play an important role in the sexually dimorphic response to antenatal glucocorticoids.

Early gestational weight gains within current recommendations result in increased risk of gestational diabetes mellitus among Korean women.

BACKGROUND: We prospectively assessed whether maternal weight gain at 24-28 weeks of gestation (MWG24) influences the risk of developing gestational complications, such as gestational diabetes mellitus (GDM) and other adverse pregnancy outcomes, in pregnant Korean women. METHODS: Maternal weight gain from self-reported pre-pregnancy weight until 24-28 weeks of gestation was measured in 731 pregnant women, and an expected MWG24 was determined using the Institute of Medicine 2009 guidelines. Glucose tolerance, insulin resistance, insulin secretory capacity, anthropometric measurements, lipid profiles, nutrient intakes and pregnancy outcomes were evaluated at 24-28 weeks of gestation. The adjusted odds ratios (ORs) for GDM, large-for-gestational-age infants, small-for-gestational-age infants and preterm delivery were determined according to maternal weight gain by logistic regression analysis after adjusting for covariates. RESULTS: Compared with a normal MWG24, an inadequate MWG24 reduced the OR (0.565) for GDM, but an excessive MWG24 did not affect the OR (0.854). However, ORs for preterm delivery were significantly higher in both inadequate and excessive MWG24 groups in comparison with the normal MWG24. There were no other adverse pregnancy outcomes due to the inadequate MWG24. MWG24 was not associated with a significant increase in ORs for delivering large-for-gestational-age or small-for-gestational-age infants or delivery by caesarean section. Although energy intake was less than the estimated energy requirement in all groups, MWG24 was linearly associated with energy intake such that energy balance was positive in the excessive MWG24 group. CONCLUSIONS: This study suggests that both target weight gain and energy intake recommendations for early pregnancy may not be optimal for Korean women and that race-specific recommendations are needed to decrease the risk of GDM without increasing adverse pregnancy outcomes.

Maternal Anemia during the First Trimester and Its Association with Psychological Health.

Anemia during pregnancy is known to be associated with an increased risk of antenatal and/or postnatal depression, as well as adverse pregnancy outcomes. However, there are few studies evaluating psychological health throughout the antepartum and postpartum periods in women with anemia in early pregnancy. This study analyzed data collected by the Korean Pregnancy Outcome Study, a multicenter prospective cohort study conducted in South Korea, to determine the impact of anemia during the first trimester on birth outcomes and maternal mental health during pregnancy and postpartum. Hemoglobin levels were measured during the first trimester, and psychological health was evaluated at 12, 24, and 36 gestational weeks and 4−6 weeks postpartum. Anxiety and depression were defined using the Hospital Anxiety and Depression Scale and the Edinburgh Postnatal Depression Scale, respectively. Among 4067 Korean participants, 119 (2.9%) were diagnosed with anemia during the first trimester. Incidences of anxiety and depression did not differ over the pregnancy period between those with and without anemia during the first trimester. However, postpartum anxiety and depression were significantly more common in participants with anemia than in those without (p < 0.05, both). Hence, obstetricians should pay attention to postpartum mental health in women with anemia during the first trimester.

Melatonin receptor 1 B polymorphisms associated with the risk of gestational diabetes mellitus.

BACKGROUNDS: Two SNPs in melatonin receptor 1B gene, rs10830963 and rs1387153 showed significant associations with fasting plasma glucose levels and the risk of Type 2 Diabetes Mellitus (T2DM) in previous studies. Since T2DM and gestational diabetes mellitus (GDM) share similar characteristics, we suspected that the two genetic polymorphisms in MTNR1B may be associated with GDM, and conducted association studies between the polymorphisms and the disease. Furthermore, we also examined genetic effects of the two polymorphisms with various diabetes-related phenotypes. METHODS: A total of 1,918 subjects (928 GDM patients and 990 controls) were used for the study. Two MTNR1B polymorphisms were genotyped using TaqMan assay. The allele distributions of SNPs were evaluated by x2 models calculating odds ratios (ORs), 95% confidence intervals (CIs), and corresponding P values. Multiple regressions were used for association analyses of GDM-related traits. Finally, conditional analyses were also performed. RESULTS: We found significant associations between the two genetic variants and GDM, rs10830963, with a corrected P value of 0.0001, and rs1387153, with the corrected P value of 0.0008. In addition, we also found that the two SNPs were associated with various phenotypes such as homeostasis model assessment of beta-cell function and fasting glucose levels. Further conditional analyses results suggested that rs10830963 might be more likely functional in case/control analysis, although not clear in GDM-related phenotype analyses. CONCLUSION: There have been studies that found associations between genetic variants of other genes and GDM, this is the first study that found significant associations between SNPs of MTNR1B and GDM. The genetic effects of two SNPs identified in this study would be helpful in understanding the insight of GDM and other diabetes-related disorders.

Treatment of gestational diabetes diagnosed by the IADPSG criteria decreases excessive fetal growth.

OBJECTIVE: We evaluated the effect on treatment using the new International Association of Diabetes and Pregnancy Study Group (IADPSG) criteria for gestational diabetes mellitus (GDM) diagnosis. METHODS: Singleton pregnant women whose plasma glucose levels were ≥140 mg/dL on the 50 g glucose challenge test (GCT) underwent 75 g oral glucose tolerance for GDM diagnosis. During the first half of the study period, GDM was diagnosed using 2 abnormal values by Carpenter-Coustan (C-C) criteria. In the second half of the study period, 1 or more abnormal values by IADPSG criteria were used for GDM diagnosis. Pregnant women were classified into 5 groups: normal 50 g GCT, positive 50 g GCT but non-GDM, GDM by IADPSG criteria and non-treated, GDM by IADPSG criteria and treated, GDM by C-C criteria and treated. The odds ratios (ORs) for large for gestational age (LGA) and macrosomia were analyzed. RESULTS: Of the 2,678 patients, the frequency of GDM diagnosed by C-C and IADPSG criteria was 2.6% and 7.5%. ORs (95% confidence intervals [CIs]) for LGA and macrosomia in the group with GDM by IADPSG criteria and non-treated were 2.81 (95% CI, 1.47-5.38) and 2.84 (95% CI, 1.08-7.47). The risk of LGA and macrosomia did not increase in the group with GDM by IADPSG criteria and treated. CONCLUSION: The risk of LGA and macrosomia for mild GDM diagnosed solely by IADPSG criteria depends on whether they are treated or not. Treatment of GDM based on IADPSG criteria reduces the risk of excessive fetal growth. TRIAL REGISTRATION: Clinical Research Information Service Identifier: KCT0000776.

[Analysis of the clinical characteristics and prognostic factors of ruptured hepatocellular carcinoma].

BACKGROUND/AIMS: Spontaneous rupture of hepatocellular carcinoma (HCC) is a rare but life-threatening complication. Although the prevalence rate and mortality of HCC has been reportedly high in Korea, studies on ruptured HCC are limited. The aim of this study was to determine the clinical characteristics and prognostic factors of ruptured HCC. METHODS: Among 886 cases with HCC that had been diagnosed at Chonnam National University Hospital from January 2002 to December 2007, 62 cases (7.0%) with ruptured HCC were studied retrospectively regarding their clinical characteristics and prognostic factors. RESULTS: Transarterial embolization was performed in 56 cases (90.3%) to control bleeding, with a hemostasis success rate of 89.3%. The survival time after the rupture of HCC was 8.0+/-1.7 months (mean+/-SD), although it was longer in HCC cases that were first diagnosed in a ruptured state or ruptured with a small amount of bleeding than in those that ruptured during follow-up after diagnosis or with a large amount of bleeding, respectively. The 30-day mortality rate in patients with a ruptured HCC was 43.5%, and the early deaths were independently associated with the presence of hepatic encephalopathy (odds ratio, OR=44.7; 95% confidence interval, CI=1.9-1051.1; P=0.018), serum bilirubin >3.0 mg/dL (OR=36.7; 95% CI=1.3-1068.5; P=0.036), and the massive or diffuse type of tumor morphology (OR=53.5; 95% CI=3.0-964.2; P=0.007). CONCLUSIONS: The prognosis in patients with ruptured HCCs was poor with a 30-day mortality of 43.5%. The early deaths after the rupture of HCC were associated with elevated serum bilirubin levels, hepatic encephalopathy, and the massive or diffuse type of tumor morphology.

Facile Multiscale Patterning by Creep-Assisted Sequential Imprinting and Fuel Cell Application.

The capability of fabricating multiscale structures with desired morphology and incorporating them into engineering applications is key to realizing technological breakthroughs by employing the benefits from both microscale and nanoscale morphology simultaneously. Here, we developed a facile patterning method to fabricate multiscale hierarchical structures by a novel approach called creep-assisted sequential imprinting. In this work, nanopatterning was first carried out by thermal imprint lithography above the glass transition temperature (Tg) of a polymer film, and then followed by creep-assisted imprinting with micropatterns based on the mechanical deformation of the polymer film under the relatively long-term exposure to mechanical stress at temperatures below the Tg of the polymer. The fabricated multiscale arrays exhibited excellent pattern uniformity over large areas. To demonstrate the usage of multiscale architectures, we incorporated the multiscale Nafion films into polymer electrolyte membrane fuel cell, and this device showed more than 10% higher performance than the conventional one. The enhancement was attributed to the decrease in mass transport resistance because of unique cone-shape morphology by creep-recovery effects and the increase in interfacial surface area between Nafion film and electrocatalyst layer.

Multiplex lithography for multilevel multiscale architectures and its application to polymer electrolyte membrane fuel cell.

The production of multiscale architectures is of significant interest in materials science, and the integration of those structures could provide a breakthrough for various applications. Here we report a simple yet versatile strategy that allows for the LEGO-like integrations of microscale membranes by quantitatively controlling the oxygen inhibition effects of ultraviolet-curable materials, leading to multilevel multiscale architectures. The spatial control of oxygen concentration induces different curing contrasts in a resin allowing the selective imprinting and bonding at different sides of a membrane, which enables LEGO-like integration together with the multiscale pattern formation. Utilizing the method, the multilevel multiscale Nafion membranes are prepared and applied to polymer electrolyte membrane fuel cell. Our multiscale membrane fuel cell demonstrates significant enhancement of performance while ensuring mechanical robustness. The performance enhancement is caused by the combined effect of the decrease of membrane resistance and the increase of the electrochemical active surface area.

Next-generation polymer-electrolyte-membrane fuel cells using titanium foam as gas diffusion layer.

In spite of their high conversion efficiency and no emission of greenhouse gases, polymer electrolyte membrane fuel cells (PEMFCs) suffer from prohibitively high cost and insufficient life-span of their core component system, the membrane electrode assembly (MEA). In this paper, we are proposing Ti foam as a promising alternative electrode material in the MEA. Indeed, it showed a current density of 462 mA cm(-2), being ca. 166% higher than that with the baseline Toray 060 gas diffusion layer (GDL) (278 mA cm(-2)) with 200 ccm oxygen supply at 0.7 V, when used as the anode GDL, because of its unique three-dimensional strut structure promoting highly efficient catalytic reactions. Furthermore, it exhibits superior corrosion resistance with almost no thickness and weight changes in the accelerated corrosion test, as opposed to considerable reductions in the weight and thickness of the conventional GDL. We believe that this paper suggests profound implications in the commercialization of PEMFCs, because the metallic Ti foam provides a longer-term reliability and chemical stability, which can reduce the loss of Pt catalyst and, hence, the cost of PEMFCs.

Ordered macroporous platinum electrode and enhanced mass transfer in fuel cells using inverse opal structure.

Three-dimensional, ordered macroporous materials such as inverse opal structures are attractive materials for various applications in electrochemical devices because of the benefits derived from their periodic structures: relatively large surface areas, large voidage, low tortuosity and interconnected macropores. However, a direct application of an inverse opal structure in membrane electrode assemblies has been considered impractical because of the limitations in fabrication routes including an unsuitable substrate. Here we report the demonstration of a single cell that maintains an inverse opal structure entirely within a membrane electrode assembly. Compared with the conventional catalyst slurry, an ink-based assembly, this modified assembly has a robust and integrated configuration of catalyst layers; therefore, the loss of catalyst particles can be minimized. Furthermore, the inverse-opal-structure electrode maintains an effective porosity, an enhanced performance, as well as an improved mass transfer and more effective water management, owing to its morphological advantages.

Foetal and neonatal outcomes in women reporting ingestion of low or very low alcohol intake during pregnancy.

OBJECTIVE: This study aimed to assess the pregnancy outcomes of women who reported social intake of low or very low alcohol levels during pregnancy. METHODS: Obstetric and foetal outcomes were assessed in a prospective cohort of 1667 pregnant women who reported low or very low alcohol consumption during pregnancy (cases) and 1840 alcohol-abstainer women (controls). RESULTS: Among cases, alcohol consumption occurred during the first 4.4 (median) weeks of pregnancy, with a median ingestion of 1.0 (0.01-6.0) drinks/week, equivalent to 7.6 (0.09-47.5) g/week. Cigarette smoking was reported approximately four times more often in the exposed group than in the controls (p < 0.001). Pregnancy outcomes were similar between groups. There were 37 (2.4%) babies born with malformations in the exposed group and 41 (2.4%) in the control group (p = 0.9). CONCLUSIONS: Low-to-very low levels of alcohol ingestion during pregnancy do not appear to be associated with adverse maternal or foetal outcomes.

Blood levels of phosphatidylethanol in pregnant women reporting positive alcohol ingestion, measured by an improved LC-MS/MS analytical method.

OBJECTIVE: A reliable biomarker of low alcohol exposure during pregnancy is needed to clarify the controversy on the teratogenicity of low-to-moderate alcohol levels. METHODS: Blood samples were obtained from 13 pregnant women who self-reported alcohol ingestion between 2.5 and 20 drinks/week, and from 26 controls. Total lipids were extracted, and phosphatidylethanol (PEth) species 16:0/16:0, 16:0/18:1, and 16:0/18:1 were separated by high-performance liquid chromatography (HPLC) on a reverse-phase phenyl column. These PEth species were quantified by MS/MS using phosphatidylpropanol as internal standard, with electrospray ionization and MRM. RESULTS: PEth species were not detected in women who abstained from alcohol ingestion during pregnancy, whereas PEth-16:0/18:1 was > 5 nmol/L in those with positive alcohol ingestion. PEth species were detected for up to 4 weeks after cessation of exposure. CONCLUSIONS: PEth-16:0/18:1 was detected in pregnant women at 4-6 weeks after their last low-to-moderate alcohol ingestion, and therefore appears to be a reliable biomarker of prenatal alcohol exposure to study the teratogenicity of alcohol at these exposure levels.

Factors associated with a positive intake of folic acid in the periconceptional period among Korean women.

OBJECTIVE: We aimed to investigate the factors associated with a positive intake of folic acid (FA) during the periconceptional period among Korean women. DESIGN: In a cross-sectional study of demographic, obstetric and socio-economic data, history of periconceptional intake of FA and awareness of the benefits of FA supplementation in pregnancy were obtained and analysed using the chi2 test, followed by multiple logistic regression analysis. SETTING: The Maternity School, Cheil General Hospital and Women's Healthcare Center, Seoul, South Korea, between October 2005 and March 2006. SUBJECTS: In total 1313 pregnant women participating in a two-day training course available every month. RESULTS: After excluding subjects with incomplete or inconsistent data, there were 1277 women included in the analysis. Participants were aged 29.4 (sd 2.9) years and had a mean gestational age of 27.9 (sd 7.1) weeks. Only 131 (10.3 %) women took FA during the periconceptional period. According to multiple logistic regression analyses, the adjusted OR for FA supplementation was 1.79 (95 % CI 1.10, 2.91) in women who had previous spontaneous abortions, 4.10 (95 % CI 2.43, 6.78) in women who planned their pregnancy and 6.63 (95 % CI 2.08, 21.12) in those who were aware of the protective effects of FA. CONCLUSIONS: Periconceptional intake of FA was more likely among Korean women with a history of previous spontaneous abortion, who planned their pregnancy or who were aware of the protective effects of FA during pregnancy. However, the proportion of women who took FA in the periconceptional period was low.

Threshold of nuchal translucency for the detection of chromosomal aberration: comparison of different cut-offs.

This study evaluated the sensitivities and false positive rates of the screening test using ultrasonographic measurement of thickness of nuchal translucency (NT) with different cut-offs for chromosomal aberration in a Korean population. We included 2,570 singleton pregnancies undergoing ultrasound between 11 weeks and 14 weeks of gestation in this study. We analyzed the sensitivities of NT alone for screening chromosomal aberration using three cut-offs -2.5 mm, 3.0 mm, and 95th percentile for each crown rump length (CRL). There were 31 chromosomal aberrations (1.2%) including 12 cases of trisomy 21. The numbers of chromosomal aberrations that were detected by NT with different cut-offs of 2.5 mm, 3.0 mm and the 95th percentile CRL were 22, 18 and 23, respectively. At a threshold of 2.5 mm, the sensitivity and the false positive rate for total chromosomal aberrations were 67.7% and 6.3%, respectively. At 3.0 mm, those were 54.8% and 3.5%, respectively. At the 95th percentile CRL, those were 70.9% and 5.8%, respectively. The use of CRL-dependent cut-offs for nuchal translucency improves the detection of chromosomal aberrations when compared to fixed cut-offs in a Korean population.