Chromosomal abnormalities occur in 0.1% to 0.2% of live births, and the most common clinically significant aneuploidy among live-born infants is Down syndrome ... a thickened nuchal fold ...

Axial image of the fetal head shows thickening of nuchal fold. Nuchal fold is measured during the second trimester on an axial image slightly off the biparietal diameter plane. The cerebellum ...