Objectives: To assess the risk of adverse pregnancy outcomes associated with fetuses with a smaller or larger than expected crown-rump length (CRL). Design: Retrospective cohort study Setting: A single center in South Korea Population: A total of 960 healthy women who conceived after in vitro fertilization. Methods: We constructed reference charts for CRL measurements between 11 and 13+6 weeks of gestation according to the gestational age. Small and large fetal CRLs were defined as CRLs below the tenth and above the ninetieth centiles, respectively. Multiple logistic regression was used to determine the risk of adverse pregnancy outcomes associated with a small or large fetal CRLs. Main Outcome Measure: Adverse pregnancy outcomes including preterm delivery, low birth weight, smaller-than-gestational-age (SGA), larger-than-gestational-age (LGA), macrosomia, and gestational diabetes. Results: A smaller than expected CRL was associated with an increased risk of SGA (adjusted odds ratio [aOR], 2.79; 95% confidence interval [CI], 1.53–5.08; p < 0.001) and preterm delivery before 34 gestational weeks (aOR, 6.48; 95% CI, 1.36–30.79; p = 0.019). A larger than expected CRL was associated with an increased risk of LGA, even after adjustment for well-known risk factors of macrosomia (aOR, 3.67; 95% CI, 2.04–6.59; p < 0.001), and a decreased risk of gestational diabetes (aOR, 0.10; 95% CI, 0.01–0.76; p = 0.026). Conclusions: A larger than expected CRL at 11 to 13+6 weeks’ gestation is independently associated with the development of LGA neonates and could be used as a predictor of excessive fetal growth.

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.