Relationship between fetal nuchal translucency and crown-rump length in an Asian population

Abstract

Objectives: To investigate the relationship between the nuchal translucency (NT) thickness and crown-rump length (CRL) in normal Asian fetuses during the first trimester. Design: A prospective observational study was conducted. Ultrasound measurement of NT and CRL was offered in 879 consecutive Taiwanese fetuses between 9 weeks and 14 weeks of gestation. Regression analysis was used to analyze the relationship between the NT thickness and CRL. Fetal sex was also considered in the analysis. The distribution of multiple of median (MoM) values of the NT measurements with CRL in 10-mm intervals and the 95th centile of MoM were also calculated. Results: The present study shows that NT measurements increase with increasing CRL. A fixed cut-off point through the first trimester is not appropriate. The NT thickness has no relationship with fetal sex. Expressing the NT thickness by MoM values provides a simple method for clinical practice. Conclusions: The present study offers normative data of the fetal NT thickness in an Asian population, which may improve the performance of NT measurement during the first trimester as a screening tool for chromosomal aberrations or other congenital abnormalities in the first trimester.