 As nuchal translucency size increases, the chances of a chromosomal abnormality and mortality increase; 65% of the largest translucencies (>6.5mm) are due to chromosomal abnormality, while fatality is 19% at this size.A nuchal scan may also help confirm both the accuracy of the pregnancy dates and the fetal viability.All women, whatever their age, have a small risk of delivering a baby with a physical or cognitive disability.