The relation between fetal nasal bone length and biparietal diameter in the Korean population

Objective To evaluate the relation between fetal nasal bone length (NBL) and biparietal diameter (BPD) at 15–19.9 (20) weeks of gestation by ultrasonography in the Korean population. Methods The study population included 1268 Korean women (aged between 19 and 45 years) with a singleton pregnancy who registered at the Maternal Fetal Medicine Unit of Samsung Cheil Hospital between September 2003 and February 2005. Ultrasound measurements of NBL were performed using a strict sagittal plan of the fetal head. Other fetal biometry profiles were conducted before amniocentesis for fetal karyotyping. Results NBL and fetal biometry profiles were measured successfully in 77.9% (988/1268) of the fetuses. NBL was found to increase linearly as a function of BPD (P < 0.001) with a median NBL of 4.4 mm (range 1.9–7.9). NBL increases through 15–19.9 (20) weeks of gestation were given by the equation NBL (mm) = 0.0836 × BPD (mm) + 1.368 (R2 = 0.1, P < 0.001). Conclusions Fetal NBL and BPD are linearly related in the second trimester. Fetal NBL in the Korean population is likely to be shorter than that reported for Caucasians and African‐Americans. Copyright © 2006 John Wiley & Sons, Ltd.