Objective To investigate the epidemiological changes in extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) vaginal colonization in high-risk pregnant women and identify independent risk factors. Further, the differences in perinatal outcomes according to maternal ESBL-E vaginal colonization were analyzed. Design Retrospective cohort study. Setting Republic of Korea Population 1,460 women admitted to our high-risk pregnancy unit between 14+0 and 35+6 gestational weeks. Methods The study period was divided into periods 1 (January 2010 to July 2015) and 2 (August 2015 to December 2020). The main outcomes were analyzed according to each period and ESBL-E vaginal colonization. Main Outcome Measures ESBL-E vaginal colonization rate, risk factors for ESBL-E vaginal colonization, and perinatal outcomes. Results The ESBL-E vaginal colonization rate was higher in period 2, which was attributed to a significantly higher proportion of ESBL-producing Escherichia coli. Cerclage (odds ratio [OR]: 3.248; 95% confidence interval [CI]: 1.744–6.049) and prior antibiotic treatment (OR: 3.044; 95% CI: 1.713–5.410) were found as independent risk factors for ESBL-E vaginal colonization. Earlier gestational age at delivery, and higher proven early-onset neonatal sepsis (EONS) rate were observed in the ESBL-E-positive group. Conclusions The ESBL-E vaginal colonization rate in high-risk pregnant patients has increased over the past decade, and the independent risk factors for colonization are cerclage and prior antibiotic treatment. Additionally, maternal ESBL-E vaginal colonization is associated with higher proven EONS rates. Funding This study received no funding. Keywords Extended-spectrum β-lactamase, Enterobacteriaceae, vaginal colonization, antibiotics use, cerclage, neonatal sepsis

Objective: Evaluate the clinical usefulness of cell-free DNA screening (cfDNA screening) in pregnancies with nuchal translucency (NT) between 95th and 99th percentile. Design: Subgroup analysis of a multicenter prospective cohort study Setting: 12 different secondary and tertiary health care institutions in Korea Sample: 7,547 singleton pregnant women with NT between 95th and 99th percentile Methods: All participants were provided with information about aneuploidy screening or diagnostic testing and selected the first tier test after NT assessment. The first tier test included maternal serum screening tests (MSS), cfDNA screening and invasive test (IT). Main outcome measures: First-tier test preference and chromosomal abnormalities in pregnancies with NT between 95th and 99th percentile Results: A total of 7,547 singleton pregnant women were enrolled and 6,717 cases with known pregnancy outcomes were analyzed. Among these, 89 (1.3%) cases showed NT between 95th and 99th percentile. As the first-tier test, 47 (52.8%) cases chose cfDNA screening, 33 (37.1%) cases selected IT, and nine (10.1%) cases underwent MSS. Chromosomal abnormalities were found in five cases (5.6%), including four cases with trisomy 21 (T21) and one with a balanced translocation. No significant chromosomal abnormalities undetected by cfDNA screening were noted in pregnancies with NT between 95th and 99th percentile. Conclusion: cfDNA screening in pregnancies with NT between 95th and 99th percentile may be considered as an acceptable alternative to invasive test for women intending to avoid the risk of miscarriage.