When the nuchal fold has a thickness of over 6 mm, the baby is considered to have a high chance of fetal abnormalities such as Down’s Syndrome, heart problems and other anomalies.
Usually, the nuchal fold grows in proportion to the developing baby. For example, when a baby measures between 45 to 84 mm (1.8 to 3.3 inches), a nuchal fold of under 3.5 mm would be considered to be within the normal range.